help button home button Endocrine Society JCEM
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Journal of Clinical Endocrinology & Metabolism , doi:10.1210/jc.2005-1398
This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Submit a related Letter to the Editor
Right arrow Alert me when this article is cited
Right arrow Alert me when eLetters are posted
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow Request Copyright Permission
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Bernini, G.
Right arrow Articles by Salvetti, A.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Bernini, G.
Right arrow Articles by Salvetti, A.
Related Collections
Right arrow Cardiovascular Endocrinology
Right arrow Male Endocrinology
The Journal of Clinical Endocrinology & Metabolism Vol. 91, No. 5 1691-1697
Copyright © 2006 by The Endocrine Society

Vascular Reactivity in Congenital Hypogonadal Men before and after Testosterone Replacement Therapy

Giampaolo Bernini, Daniele Versari, Angelica Moretti, Agostino Virdis, Lorenzo Ghiadoni, Michele Bardini, Chiara Taurino, Domenico Canale, Stefano Taddei and Antonio Salvetti

Departments of Internal Medicine (G.B., D.V., A.M., A.V., L.G., M.B., C.T., S.T., A.S.) and Endocrinology (D.C.), Pisa University, 56100 Pisa, Italy

Address all correspondence and requests for reprints to: Bernini Giampaolo, M.D., Department of Internal Medicine, University of Pisa, Via Roma 67, 56100 Pisa, Italy. E-mail: g.bernini{at}int.med.unipi.it.


   Abstract
Top
 Abstract
Introduction
 Subjects and Methods
 Results
 Discussion
 References
 
Context: The contribution of endogenous testosterone (TS) in the functional integrity of peripheral circulation in men was studied.

Objective: The objective of this study was to observe vascular reactivity in male congenital hypogonadal patients before and after prolonged exposure to normal TS levels.

Design: This was a longitudinal study in which, basically and after 6-month (range, 6–8 months) androgen treatment, we investigated forearm blood flow (strain-gauge plethysmography) changes induced by intraarterial acetylcholine (Ach), alone or in the presence of NG-monomethyl-L-arginine infusion, and by sodium nitroprusside. We also evaluated, by Doppler ultrasound, flow-mediated dilation of the brachial artery (BA) in response to reactive hyperemia (RH) and glyceryl trinitrate (GTN).

Setting: The studies were conducted at university referral centers for andrologic and blood pressure diseases.

Patients: Eight adult male Caucasian hypogonadal patients and nine healthy matched control subjects were studied.

Intervention: Intervention was TS enanthate (250 mg in 1 ml oily solution) by im injection every 3 wk.

Results: At baseline, BA diameter and RH, flow-mediated dilation, and GTN responses showed no difference between the two groups. TS therapy increased plasma total TS (P < 0.02) and reduced high-density lipoprotein (P < 0.01) and total cholesterol (P < 0.04). It did not affect vasodilation to sodium nitroprusside (355 ± 47%), but it further reduced the vascular response to Ach (187 ± 29%, P < 0.01 vs. baseline) and abolished the inhibition by NG-monomethyl-L-arginine on Ach (inhibition, 3.2%). Moreover, TS therapy decreased (P < 0.01) flow-mediated dilation, whereas it did not modify BA diameter and responses to RH and GTN.

Conclusions: Hypogonadal patients show impaired vascular reactivity, including endothelial-dependent vasodilation due to reduced nitric oxide availability. TS administration further impairs nitric oxide availability in these patients.


   Introduction
Top
 Abstract
 Introduction
Subjects and Methods
 Results
 Discussion
 References
 
THE ROLE OF androgens in the male cardiovascular system is still under debate. Some observations suggest that these hormones exert a deleterious effect on the cardiovascular system. Men are twice as likely to die from coronary heart disease as women (1). Anabolic steroid (androgen) abusers frequently undergo sudden cardiac death (2). Genetic females using high-dose androgens (female-to-male transsexuals) show impaired vascular function (3), whereas androgen-deprived prostate cancer patients have enhanced vascular reactivity (4).

However, data obtained from a comprehensive review of the literature, including cross-sectional clinical studies and prospective cohort or nested case-control studies, show the lack of a positive relationship between testosterone (TS) and coronary artery disease, thus suggesting that high TS levels do not behave as a cardiovascular risk factor (5).

Recent evidence even supports a positive role of androgens on the cardiovascular system (5, 6, 7, 8). TS induces direct vasodilation in a variety of vascular beds through a nongenomic pathway, involving the membranous ion channel function (9). An antiatherogenic action of TS has been observed in several in vitro models of arterial plaque development (10) and in cholesterol-fed animal models (11, 12, 13, 14). Epidemiological studies show an inverse relation between plasma TS in elderly men and the presence of aortic and carotid atherosclerosis (15, 16) as well as an association between low serum levels of TS and coronary artery disease or coronary events (5, 17). Finally, clinical investigations have demonstrated that acute or chronic TS administration improves myocardial ischemia (18, 19, 20, 21) and cardiac performance (22) in eugonadal men with coronary artery disease and chronic heart failure, respectively.

Thus, the real influence of androgens on the cardiovascular system remains controversial, even though several factors may explain the discrepancies observed in the literature. Gender, age, and cardiovascular status of the patients studied are important in this respect. Furthermore, investigations exploring the effects of endogenous TS provide different information compared with findings obtained after exogenous TS administration, and the results also vary in relation to the dose, type, and duration of treatment. Finally, different effects may be observed depending on the endogenous androgen milieu of the patients studied, i.e. based on whether they are eugonadal or affected by (congenital or acquired) hypogonadism.

Thus, the aim of our study was to investigate the contribution of endogenous TS in the functional integrity of peripheral circulation. For this reason, we chose a human model of adult congenital hypogonadal men in whom vascular reactivity was evaluated before and after prolonged exposure to normal TS levels. The few studies on vascular function in hypogonadal patients available in the literature were all performed in conduit arteries by noninvasive ultrasound techniques (23, 24, 25, 26). Therefore, in the present study, we explored vascular function also in forearm resistance arteries, in which endothelial dysfunction has been demonstrated to be an independent predictor of cardiovascular events (27).


   Subjects and Methods
Top
 Abstract
 Introduction
 Subjects and Methods
Results
 Discussion
 References
 
Subjects

The study population included eight adult male Caucasian hypogonadal patients and nine healthy control subjects, matched for demographic, hemodynamic, and humoral characteristics (Table 1Go).


View this table:
[in this window]
[in a new window]
  		TABLE 1. Demographic, hemodynamic, and humoral characteristics of study population

 
Six patients were affected by isolated hypogonadotropic hypogonadism with other pituitary hormones in the normal range (Kallmann’s syndrome in two cases and idiopathic hypothalamic-pituitary hypogonadism in four cases), whereas two other hypogonadal patients were affected by hypergonadotropic hypogonadism (Klinefelter’s syndrome). Thus, the patients had in common a congenital low concentration of plasma TS. This diagnosis had been hypothesized in young age in all patients with secondary and in one patient with primary hypogonadism because of delayed puberty with sexual infantilism (n = 5) or incomplete sexual development (n = 2) and eunuchoid proportion. The diagnosis of the other patient with Klinefelter’s syndrome had been made upon routine physical examination detecting firm and small testis, signs of androgen deficiency, and gynecomastia. All patients had been referred to the andrology clinic and, after diagnosis confirmation by proper investigations, enrolled in the study because they had undergone no previous treatment with hormone therapy (n = 5) or had discontinued therapy with human chorionic gonadotropin (n = 1) or with TS (n = 2) for at least 8 months (range, 8–12 months) before testing. None of the latter three patients had started hormone therapy before the age of 18 yr, and treatment duration had been less than 5 months.

Individuals with smoking history, ethanol consumption (more than 60 g, 0.5 liters wine/d), diabetes mellitus, cardiac and/or cerebrovascular ischemic vascular disease, impaired renal function, and other major pathologies were excluded. In accordance with institutional guidelines, the protocol was approved by the local Ethical Committee, and all participants gave written consent to the study.

Experimental design

Patients and controls underwent basal blood sampling, in fasting and sitting conditions, for plasma total TS (T-TS), dehydroepiandrosterone-sulfate (DHEA-S), androstenedione, 17ß-estradiol (E2), and estrone (E1) determination. In addition, basal evaluation of vascular reactivity in resistance and conduit arteries was performed on both groups. Patients were then submitted to TS replacement therapy for at least 6 months (range, 6–8 months) with TS enanthate (250 mg in 1 ml oily solution) by im injection. This drug was administered at variable doses (100 mg im in two patients and 250 mg im in six patients) every 3 wk, depending on symptoms described by patients and/or to obtain TS levels within the normal range.

Hormonal and vascular evaluation was repeated at the end of the replacement therapy period in hypogonadal patients and after 6 months in control subjects.

Experimental procedures

Resistance arteries. Vascular reactivity of peripheral resistance vessels was assessed by the perfused forearm technique. Briefly, the brachial artery (BA) was cannulated for drug infusion at systemically ineffective rates and for intraarterial blood pressure and heart rate monitoring. Forearm blood flow (FBF) was measured in both the experimental and contralateral forearms by strain-gauge venous plethysmography. Circulation to the hand was excluded 1 min before FBF measurement by inflating a pediatric cuff around the wrist at suprasystolic blood pressure. Details concerning the method have already been published (28).

Endothelium-dependent vasodilation was estimated by a dose-response curve to intraarterial acetylcholine (Ach; Farmigea S.p.A., Pisa, Italy; cumulative increase of infusion rates, 0.15, 0.45, 1.5, 4.5, and 15 µg/100 ml forearm tissue·min for 5 min at each dose). Endothelium-independent vasodilation was assessed by a dose-response curve to intraarterial sodium nitroprusside (SNP; Malesci, Milan, Italy; 1, 2, and 4 µg/100 ml·min, 5 min each dose), a direct smooth muscle relaxant compound. To evaluate NO availability, Ach was repeated in the presence of intraarterial NG-monomethyl-L-arginine (L-NMMA; Clinalfa AG, Läufelfingen, Switzerland; 100 µg/100 ml·min), a specific nitric oxide synthase inhibitor (29). L-NMMA was started 10 min before Ach and continued throughout. Infusions under L-NMMA were performed according to the NO-clamp technique, which requires SNP coinfusion (0.4 and 0.3 µg/100 ml tissue·min for 5 min in control subjects and hypogonadal patients, respectively) to neutralize the L-NMMA-induced vasoconstriction and restore baseline FBF. Details concerning the method as performed in our laboratory have already been published (30).

Conduit arteries. Endothelium-dependent vasodilation was assessed as flow-mediated dilation (FMD) of the BA. A B-mode scan of the right BA was obtained in longitudinal section between 5 and 10 cm above the elbow, using a 7.0-MHz linear array transducer and a standard AU5 Armonic system (ESAOTE S.p.A., Genova, Italy) as described previously (31). Briefly, the transducer was held at the same point throughout the scan by a stereotactic clamp. End-diastolic frames (electrocardiogram triggered) were acquired every second on a personal computer with the use of a commercial software program (miroVIDEO DC 30/plus, Pinnacle Systems GmbH, Braunschweig, Germany).

After 1 min of acquisition to measure basal diameter, a cuff, placed around the forearm just below the elbow, was inflated for 5 min at 250 mm Hg and then deflated to induce reactive hyperemia (RH). Endothelium-independent dilation was obtained by administration of a low dose (25 µg) of sublingual glyceryl trinitrate (GTN). Arterial flow velocity was obtained by pulsed Doppler signal at 70° to the vessel with the range gate (1.5 mm) in the center of the artery.

Hormonal evaluation. All hormones were assayed in duplicate using specific commercial RIA kits. Intra- and interassay CVs of the hormones were: DHEA-S (Radim, Rome, Italy), 6.8 and 8.1%; androstenedione (Sorin, Saluggia, Italy), 7.1 and 10.8%; T-TS (Medical System, Genova, Italy), 6.0 and 7.8%; E2 (Orion Diagnostica, Espoo, Finland), 7.3 and 10.3%; and E1 (DSL Inc., Webster, TX), 6.4 and 9.1%.

Data analysis

In the resistance vessel reactivity studies, data were analyzed in terms of changes in FBF. Because arterial blood pressure did not change significantly, increments in FBF were taken as evidence of local vasodilation. In the conduit arteries reactivity experiments, BA measurements were performed on acquired frames by the computerized edge detection system (32, 33). Baseline BA diameter was the mean of measures obtained during the first minute. FMD and response to GTN were calculated as the maximal percent increase in diameter above baseline. FMD was also calculated as area under the curve (AUC) of the percent change in diameter after RH.

Blood flow volume was calculated by multiplying Doppler flow velocity (corrected for the angle) by heart rate and vessel cross-sectional area ({pi}r2). Flow velocity was measured at baseline and within 15 sec after cuff release. RH was calculated as percent increase in flow after cuff release compared with baseline flow.

FBF and FMD analyses were performed by observers (A.V. and L.G., respectively) who had no knowledge of the individual hormone plasma levels. In our laboratory, within-observer and interobserver variability of the FBF technique is 3.5 and 5%, respectively (34), whereas for the FMD technique, within-observer and interobserver variability of the computerized analysis is less than 1%. The coefficient of variation of two different measurements of FMD over time is 14% (32). To ensure that endothelium-dependent VD in the microcirculation was normalized for the endothelium-independent response, maximal response to Ach was divided by maximal response to SNP. The study population characteristics (demographic, hemodynamic, humoral, and hormonal data) were compared by the unpaired Student’s t test or one-way ANOVA, when appropriate. Responses to Ach and SNP were analyzed by ANOVA for repeated measures and Scheffè’s test was applied for multiple comparison testing. Results were expressed as mean ± SEM. P < 0.05 was considered statistically significant.


   Results
Top
 Abstract
 Introduction
 Subjects and Methods
 Results
Discussion
 References
 
Demographic, hemodynamic, and humoral parameters

At baseline, there was no significant difference in demographic, hemodynamic, and metabolic characteristics between controls and patients. As expected, plasma values of T-TS were lower in hypogonadal patients than in controls, without significant differences between the two groups as regards the other endocrine parameters (Table 1Go).

In controls all parameters studied remained unchanged after 6 months. In hypogonadal patients, TS administration failed to affect BMI and plasma glucose, slightly decreased triglycerides, low-density lipoprotein-cholesterol, and blood pressure values, and significantly reduced total and high-density lipoprotein (HDL)-cholesterol levels. In addition, TS administration significantly raised plasma T-TS without modifying the other endocrine parameters (Table 1Go).

Vascular reactivity in resistance arteries

At baseline, a significantly (P < 0.01) smaller FBF increase was induced by Ach in hypogonadal patients (from 3.1 ± 0.4 to a maximum of 15.1 ± 3.2 ml/100 ml·min, +387%) compared with control subjects (from 3.0 ± 0.4 to a maximum of 25.6 ± 3.2 ml/100 ml·min, +753%) (Fig. 1Go, A and B). In healthy controls, as expected, vasodilation to Ach was significantly blunted by L-NMMA (baseline, 3.1 ± 0.4; L-NMMA, 2.0 ± 0.3; L-NMMA plus SNP, 3.1 ± 0.5; L-NMMA plus SNP and Ach, 11.4 ± 2.3 ml/100 ml·min, +268%) (Fig. 1AGo). In contrast, in hypogonadal patients, the inhibitory effect of L-NMMA on the response to Ach was reduced and significantly present only at the highest dose of the muscarinic agonist (baseline, 3.1 ± 0.4; L-NMMA, 2.6 ± 0.3; L-NMMA plus SNP, 3.0 ± 0.5; L-NMMA plus SNP and Ach, 11.9 ± 2.5 ml/100 ml·min, +297%) (Fig. 1BGo). In terms of degree of inhibition, the percent inhibitory effect by L-NMMA on response to Ach was lower in hypogonadal patients compared with healthy controls (23.3 vs. 64.4%, respectively) (Fig. 2Go). At baseline, the vasodilating effect of SNP was also significantly less evident in hypogonadal patients (from 3.2 ± 0.5 to a maximum of 14.3 ± 2.4 ml/100 ml·min, +347%) in comparison with healthy controls (from 3.1 ± 0.5 to a maximum of 20.9 ± 2.4 ml/100 ml·min, +574%) (Fig. 3Go). The Ach to SNP ratio was significantly (P < 0.01) lower in patients (1.17 ± 0.56) compared with controls (1.38 ± 0.61).


Figure 1
View larger version (13K):
[in this window]
[in a new window]
  		FIG. 1. Line graphs show absolute FBF increase above basal induced by Ach during saline or L-NMMA in healthy controls and hypogonadal patients at baseline and after TS replacement therapy (treatment). Data are shown as means ± SEM. B, Basal; *, P < 0.01; {dagger}, P < 0.05.

 

Figure 2
View larger version (10K):
[in this window]
[in a new window]
  		FIG. 2. Bars show percent inhibition by L-NMMA on the maximal vasodilation induced by Ach in healthy controls and hypogonadal patients in basal conditions (baseline) and after TS replacement therapy (treatment). Data are shown as means ± SEM. *, P < 0.001 vs. other groups; {dagger}, P < 0.05 vs. hypogonadal patients at baseline.

 

Figure 3
View larger version (21K):
[in this window]
[in a new window]
  		FIG. 3. Line graphs show absolute FBF increase above basal induced by SNP in healthy controls and hypogonadal patients in basal conditions (baseline) and after TS replacement therapy (treatment). Data are shown as means ± SEM. *, P < 0.05.

 
In the time-control study conducted in healthy controls, the 6-month period caused no change in either the vasodilating effect of Ach (from 3.1 ± 0.5 to 25.3 ± 2.4 ml/100 ml·min, +716%) or the vascular response to SNP (from 3.1 ± 0.5 to 20.6 ± 2.4 ml/100 ml·min, +564%) and also did not modify the inhibitory effect of L-NMMA on Ach (baseline, 3.2 ± 0.4; L-NMMA, 2.1 ± 0.3; L-NMMA plus SNP, 3.1 ± 0.5; L-NMMA plus SNP and Ach, 11.2 ± 2.2 ml/100 ml·min, +261%) compared with baseline values (data not shown). After TS replacement therapy, in hypogonadal patients, the vascular response to Ach was further reduced (from 3.0 ± 0.5 to 8.6 ± 2.4 ml/100 ml·min, +187%) in comparison with preintervention results (P < 0.05) (Fig. 1Go, B and C). In addition, hormone therapy virtually abolished the inhibitory effect of L-NMMA on vascular response to Ach (baseline, 3.0 ± 0.4; L-NMMA, 2.6 ± 0.3; L-NMMA plus SNP, 3.1 ± 0.4; L-NMMA plus SNP and Ach, 8.7 ± 2.2 ml/100 ml·min, +180%; inhibition, 3.2%) (Figs. 1CGo and 2Go). Finally, hormone therapy did not affect the reduced response to SNP (from 3.1 ± 0.5 to 14.1 ± 2.1 ml/100 ml·min, +355%) (Fig. 3Go).

In all subjects, contralateral FBF showed no significant change throughout the study (data not shown).

Vascular reactivity in conduit arteries

In hypogonadal patients and controls, baseline BA diameter (3.98 ± 0.16 and 4.13 ± 0.19 mm, respectively) and RH (555 ± 106% and 578 ± 118%, respectively) were similar. FMD did not differ in hypogonadal patients (7.5 ± 0.8%; AUC, 652 ± 104 U) compared with controls (7.3 ± 0.7%; AUC, 631 ± 102 U). Response to GTN was also similar in the two groups (8.3 ± 1.1% and 7.8 ± 1.2%, respectively) (Fig. 4Go).


Figure 4
View larger version (11K):
[in this window]
[in a new window]
  		FIG. 4. Bars show percentage increase in diameter induced by RH (FMD) and GTN in healthy controls (before and after 6 months) and in hypogonadal patients at baseline and after TS treatment. Data are shown as means ± SEM. *, P < 0.01.

 
In controls, the 6-month period did not affect either FMD (7.4 ± 0.6%; AUC, 637 ± 98 U) or response to GTN (8.1 ± 1.3%) as compared with baseline values (Fig. 4Go). In hypogonadal patients, hormone replacement therapy did not modify BA diameter (4.01 ± 0.19 mm), RH (502 ± 106%), or response to GTN (8.5 ± 1.2%), whereas it significantly decreased FMD (6.0 ± 1.0%; AUC, 456 ± 113 U), compared with baseline (Fig. 4Go).

Correlations

In both groups, no correlation between Ach and SNP responses and hemodynamic, humoral, or hormonal parameters was found, either in basal conditions or at the end of the study.

Moreover, in both groups, no correlation was found between Doppler ultrasound-derived indexes (FMD and GTN responses) and hemodynamic, humoral, or hormonal parameters, either in basal conditions or at the end of the study.


   Discussion
Top
 Abstract
 Introduction
 Subjects and Methods
 Results
 Discussion
References
 
The results of the present study show that in conduit arteries of congenital hypogonadal adult men, vascular reactivity is similar to normal subjects, whereas in resistance arteries, it is profoundly deranged due to a reduction in endothelium-independent and -dependent vasodilation, the latter being attributable to blunted NO availability. In addition, our data demonstrate that TS replacement therapy impairs endothelium-dependent function in these patients both in the macrocirculation and microcirculation by further reducing NO bioavailability.

Our study was performed in a peculiar human model, namely adult male congenital hypogonadism, a pathological condition in which androgen receptors are not exposed to normal androgen concentrations and to physiological androgen fluctuations during adolescence and puberty. Our findings on forearm resistance arteries in these patients clearly showed that the lack of endogenous androgens since birth is associated with global vascular reactivity derangement in adulthood. This abnormality is characterized by reduced endothelium-dependent as well as -independent vasodilation. It is worth noting that the reduction in endothelial agonist-induced vasodilation is more evident as compared with the effect consequent to the direct smooth muscle cell relaxant compound. This suggests that chronic absence of TS deeply affects endothelial function, as also confirmed by the reduction in NO availability observed in our patients. Therefore, this is the first report obtained in the peripheral microcirculation of hypogonadal patients suggesting that a normal androgenic tone constitutes a crucial factor in the development and maintenance of normal vascular function in men.

The findings we obtained in the peripheral microcirculation were not confirmed in the macrocirculation because vascular reactivity in conduit arteries recorded by Doppler ultrasound was similar to that observed in eugonadal controls. The different results obtained in resistance vs. conduit arteries could have an underlying pathophysiological cause or be attributable to methodological aspects. Firstly, taking into account that the endothelium acts as a paracrine-autocrine organ, the TS-induced dysfunction in the microcirculation may precede or be predominant when compared with that occurring in conduit arteries. Secondly, although FMD is the response of a single vessel to an on-off stimulus, the plethysmographic technique explores the integrated endothelial response in forearm microcirculation to a graded agonist-induced dose response. Therefore, we cannot rule out that the low sensitivity of FMD may underestimate the influence of androgens and that only by increasing the number of the patients could the relationship between these hormones and peripheral macrocirculation be highlighted. Zitzmann et al. (25) recently reported higher endothelium-dependent FMD in hypogonadal men compared with eugonadal controls. However, the patients enrolled in his study were older (age range, 20–70 yr vs. 19–36 yr), and the clinical model adopted was completely different. We studied only untreated patients with congenital hypogonadism, whereas his data derived from a combined analysis of patients with congenital (n = 11) and acquired (n = 25) hypogonadism. The vascular responses of patients never exposed to normal TS tone may have been different from those of patients deprived of androgen in adulthood.

An additional important finding of the present study is that, unexpectedly, prolonged TS replacement therapy further impaired endothelium-dependent vasodilatation, without any effect on response to SNP. This action appeared to be exerted through complete removal of available NO, as shown by the lack of inhibitory effect of L-NMMA on Ach-induced vasodilatation. The selective worsening effect of TS on endothelial function was also demonstrated by Doppler ultrasound in the BA of our patients, who showed a significant reduction in FMD but not in response to GTN. Taken together, these findings suggest that in the case of congenital androgen deficiency in which vascular reactivity is strongly affected, long-term exogenous TS, even at adequate doses, behaves as an oxidative stressor factor leading to further impairment of endothelial function. It has been reported, in studies conducted by BA Doppler ultrasound, that acute high-dose TS injection (35) or chronic oral TS administration at physiological doses (36) enhances endothelium-dependent and -independent vasodilation in eugonadal patients with coronary artery disease. Such data showing a positive action of TS on the peripheral vasculature would appear to be in disagreement with our results. However, a comparative assessment is difficult because the models studied are completely different. In our investigation, the patients had congenital hypogonadism, whereas in the cited reports, they had a preexisting normal androgen milieu, so that the impact of TS on the vascular receptors might be different.

Although our study was obtained by means of a very sensitive methodological procedure of strain-gauge plethysmography in resistance arteries, it does not allow us to clarify the basic mechanisms involved in the phenomena observed. In particular, we do not know how chronic androgen deficiency affects vascular function and why the restoration of a physiological androgenic milieu in the same vessels likewise impairs vascular function. Our results are unlikely to be due to a possible subtherapeutic dose of TS, as the doses administered, although quite low at least in some cases, improved hypogonadism-related symptoms and signs in all patients and increased mean TS levels up to 4-fold, starting from very low basal values. In addition, the worsening effect of TS on endothelial function, demonstrated by Doppler ultrasound in the BA, was also found in two other reports (25, 26) using higher TS replacement doses that achieved more elevated endogenous TS values than those obtained in our study. In contrast, a time effect should be taken into account to explain our data because recovery of normal vascular function might occur only after a longer period of exposure to physiological TS concentrations than planned by our protocol study. Finally, we cannot rule out the possibility that the negative vascular effect of exogenous TS was indirect, as suggested in particular by the observed reduction in HDL-cholesterol, a finding already reported during TS replacement therapy (5), which is a known factor of vascular protection and appears to be positively related to endothelial function (37, 38).

In conclusion, our data indicate that an adequate endogenous androgenic tone exerts a crucial role in the physiological development of vascular reactivity of peripheral microcirculation in men. Long-term TS replacement therapy does not improve vascular reactivity but further impairs endothelial function. This negative effect could, however, be explained by the unfavorable impact of TS on lipid profile. Because endothelium dysfunction is emerging as an important cardiovascular risk factor, our data imply that in patients undergoing TS replacement therapy, careful surveillance should be conducted to monitor for a possible increase in the global cardiovascular risk.


   Footnotes
 
All authors (G.B., D.V., A.M., A.V., L.G., M.B., C.T., D.C., S.T., A.S.) have nothing to declare.

First Published Online February 21, 2006

Abbreviations: Ach, Acetylcholine; AUC, area under the curve; BA, brachial artery; DHEA-S, dehydroepiandrosterone-sulfate; E1, estrone; E2, 17ß-estradiol; FBF, forearm blood flow; FMD, flow-mediated dilation; GTN, glyceryl trinitrate; HDL, high-density lipoprotein; L-NMMA, NG-monomethyl-L-arginine; RH, reactive hyperemia; SNP, sodium nitroprusside; TS, testosterone; T-TS, total TS.

Received June 23, 2005.

Accepted February 6, 2006.


   References
Top
 Abstract
 Introduction
 Subjects and Methods
 Results
 Discussion
 References
 

  1. Mendelsohn ME, Karas RH 1999 The protective effects of estrogen on the cardiovascular system. N Engl J Med 340:1801–1811[Free Full Text]
  2. Sullivan ML, Martinez CM, Gennis P, Gallagher EJ 1998 The cardiac toxicity of anabolic steroids. Prog Cardiovasc Dis 41:1–15[Medline]
  3. McCredie RJ, McCrohon JA, Turner L, Griffiths KA, Handelsman DJ, Celermajer DS 1998 Vascular reactivity is impaired in genetic females taking high-dose androgens. J Am Coll Cardiol 32:1331–1335[Abstract/Free Full Text]
  4. Herman SM, Robinson JT, McCredie RJ, Adams MR, Boyer MJ, Celermajer DS 1997 Androgen deprivation is associated with enhanced endothelium-dependent dilatation in adult men. Arterioscler Thromb Vasc Biol 17:2004–2009[Abstract/Free Full Text]
  5. Wu FC, von Eckardstein A 2003 Androgens and coronary artery disease. Endocr Rev 24:183–217[Abstract/Free Full Text]
  6. Jones RD, Hugh Jones T, Channer KS 2004 The influence of testosterone upon vascular reactivity. Eur J Endocrinol 151:29–37[Abstract]
  7. Liu PY, Death AK, Handelsman DJ 2003 Androgens and cardiovascular disease. Endocr Rev 24:313–340[Abstract/Free Full Text]
  8. Orshal JM, Khalil RA 2004 Gender, sex hormones, and vascular tone. Am J Physiol Regul Integr Comp Physiol 286:R233–R249
  9. Jones RD, Pugh PJ, Jones TH, Channer KS 2003 The vasodilatory action of testosterone: a potassium-channel opening or a calcium antagonistic action? Br J Pharmacol 138:733–744[CrossRef][Medline]
  10. Hanke H, Lenz C, Hess B, Spindler KD, Weidemann W 2001 Effect of testosterone on plaque development and androgen receptor expression in the arterial vessel wall. Circulation 103:1382–1385[Abstract/Free Full Text]
  11. Larsen BA, Nordestgaard BG, Stender S, Kjeldsen K 1993 Effect of testosterone on atherogenesis in cholesterol-fed rabbits with similar plasma cholesterol levels. Atherosclerosis 99:79–86[CrossRef][Medline]
  12. Nathan L, Shi W, Dinh H, Mukherjee TK, Wang X, Lusis AJ, Chaudhuri G 2001 Testosterone inhibits early atherogenesis by conversion to estradiol: critical role of aromatase. Proc Natl Acad Sci USA 98:3589–3593[Abstract/Free Full Text]
  13. Alexandersen P, Haarbo J, Byrjalsen I, Lawaetz H, Christiansen C 1999 Natural androgens inhibit male atherosclerosis: a study in castrated, cholesterol-fed rabbits. Circ Res 84:813–819[Abstract/Free Full Text]
  14. Bruck B, Brehme U, Gugel N, Hanke S, Finking G, Lutz C, Benda N, Schmahl FW, Haasis R, Hanke H 1997 Gender-specific differences in the effects of testosterone and estrogen on the development of atherosclerosis in rabbits. Arterioscler Thromb Vasc Biol 17:2192–2199[Abstract/Free Full Text]
  15. Hak AE, Witteman JC, de Jong FH, Geerlings MI, Hofman A, Pols HA 2002 Low levels of endogenous androgens increase the risk of atherosclerosis in elderly men: the Rotterdam study. J Clin Endocrinol Metab 87:3632–3639[Abstract/Free Full Text]
  16. van den Beld AW, Bots ML, Janssen JA, Pols HA, Lamberts SW, Grobbee DE 2003 Endogenous hormones and carotid atherosclerosis in elderly men. Am J Epidemiol 157:25–31[Abstract/Free Full Text]
  17. Alexandersen P, Haarbo J, Christiansen C 1996 The relationship of natural androgens to coronary heart disease in males: a review. Atherosclerosis 125:1–13[CrossRef][Medline]
  18. Jaffe MD 1977 Effect of testosterone cypionate on postexercise ST segment depression. Br Heart J 39:1217–1222[Abstract/Free Full Text]
  19. Wu SZ, Weng XZ 1993 Therapeutic effects of an androgenic preparation on myocardial ischemia and cardiac function in 62 elderly male coronary heart disease patients. Chin Med J (Engl) 106:415–418[Medline]
  20. Rosano GM, Leonardo F, Pagnotta P, Pelliccia F, Panina G, Cerquetani E, della Monica PL, Bonfigli B, Volpe M, Chierchia SL 1999 Acute anti-ischemic effect of testosterone in men with coronary artery disease. Circulation 99:1666–1670[Abstract/Free Full Text]
  21. English KM, Steeds RP, Jones TH, Diver MJ, Channer KS 2000 Low-dose transdermal testosterone therapy improves angina threshold in men with chronic stable angina: a randomized, double-blind, placebo-controlled study. Circulation 102:1906–1911[Abstract/Free Full Text]
  22. Pugh PJ, Jones RD, West JN, Jones TH, Channer KS 2004 Testosterone treatment for men with chronic heart failure. Heart 90:446–447[Free Full Text]
  23. Ly LP, Jimenez M, Zhuang TN, Celermajer DS, Conway AJ, Handelsman DJ 2001 A double-blind, placebo-controlled, randomized clinical trial of transdermal dihydrotestosterone gel on muscular strength, mobility, and quality of life in older men with partial androgen deficiency. J Clin Endocrinol Metab 86:4078–4088[Abstract/Free Full Text]
  24. Kenny AM, Bellantonio S, Gruman CA, Acosta RD, Prestwood KM 2002 Effects of transdermal testosterone on cognitive function and health perception in older men with low bioavailable testosterone levels. J Gerontol A Biol Sci Med Sci 57:M321–M325
  25. Zitzmann M, Brune M, Nieschlag E 2002 Vascular reactivity in hypogonadal men is reduced by androgen substitution. J Clin Endocrinol Metab 87:5030–5037[Abstract/Free Full Text]
  26. Sader MA, Griffiths KA, Skilton MR, Wishart SM, Handelsman DJ, Celermajer DS 2003 Physiological testosterone replacement and arterial endothelial function in men. Clin Endocrinol (Oxf) 59:62–67[CrossRef][Medline]
  27. Heitzer T, Schlinzig T, Krohn K, Meinertz T, Munzel T 2001 Endothelial dysfunction, oxidative stress, and risk of cardiovascular events in patients with coronary artery disease. Circulation 104:2673–2678[Abstract/Free Full Text]
  28. Taddei S, Virdis A, Ghiadoni L, Magagna A, Salvetti A 1998 Vitamin C improves endothelium-dependent vasodilation by restoring nitric oxide activity in essential hypertension. Circulation 97:2222–2229[Abstract/Free Full Text]
  29. Vallance P, Collier J, Moncada S 1989 Effects of endothelium-derived nitric oxide on peripheral arteriolar tone in man. Lancet 2:997–1000[Medline]
  30. Virdis A, Ghiadoni L, Cardinal H, Favilla S, Duranti P, Birindelli R, Magagna A, Bernini G, Salvetti G, Taddei S, Salvetti A 2001 Mechanisms responsible for endothelial dysfunction induced by fasting hyperhomocystinemia in normotensive subjects and patients with essential hypertension. J Am Coll Cardiol 38:1106–1115[Abstract/Free Full Text]
  31. Ghiadoni L, Magagna A, Versari D, Kardasz I, Huang Y, Taddei S, Salvetti A 2003 Different effect of antihypertensive drugs on conduit artery endothelial function. Hypertension 41:1281–1286[Abstract/Free Full Text]
  32. Beux F, Carmassi S, Salvetti MV, Ghiadoni L, Huang Y, Taddei S, Salvetti A 2001 Automatic evaluation of arterial diameter variation from vascular echographic images. Ultrasound Med Biol 27:1621–1629[CrossRef][Medline]
  33. Ghiadoni L, Huang Y, Magagna A, Buralli S, Taddei S, Salvetti A 2001 Effect of acute blood pressure reduction on endothelial function in the brachial artery of patients with essential hypertension. J Hypertens 19:547–551[CrossRef][Medline]
  34. Pedrinelli R, Taddei S, Graziadei L, Salvetti A 1986 Vascular responses to ouabain and norepinephrine in low and normal renin hypertension. Hypertension 8:786–792[Abstract/Free Full Text]
  35. Ong PJ, Patrizi G, Chong WC, Webb CM, Hayward CS, Collins P 2000 Testosterone enhances flow-mediated brachial artery reactivity in men with coronary artery disease. Am J Cardiol 85:269–272[CrossRef][Medline]
  36. Kang SM, Jang Y, Kim JY, Chung N, Cho SY, Chae JS, Lee JH 2002 Effect of oral administration of testosterone on brachial arterial vasoreactivity in men with coronary artery disease. Am J Cardiol 89:862–864[CrossRef][Medline]
  37. Spieker LE, Sudano I, Hurlimann D, Lerch PG, Lang MG, Binggeli C, Corti R, Ruschitzka F, Luscher TF, Noll G 2002 High-density lipoprotein restores endothelial function in hypercholesterolemic men. Circulation 105:1399–1402[Abstract/Free Full Text]
  38. O’Connell BJ, Genest Jr J 2001 High-density lipoproteins and endothelial function. Circulation 104:1978–1983[Abstract/Free Full Text]



This article has been cited by other articles:


Home page
 Eur J EndocrinolHome page
M. Yaron, Y. Greenman, J. B Rosenfeld, E. Izkhakov, R. Limor, E. Osher, G. Shenkerman, K. Tordjman, and N. Stern
Effect of testosterone replacement therapy on arterial stiffness in older hypogonadal men
Eur. J. Endocrinol., May 1, 2009; 160(5): 839 - 846.
[Abstract] [Full Text] [PDF]

Home page
 Am. J. Physiol. Endocrinol. Metab.Home page
L. A. Sokolnicki, S. Khosla, and N. Charkoudian
Effects of testosterone and estradiol on cutaneous vasodilation during local warming in older men
Am J Physiol Endocrinol Metab, November 1, 2007; 293(5): E1426 - E1429.
[Abstract] [Full Text] [PDF]

This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Submit a related Letter to the Editor
Right arrow Alert me when this article is cited
Right arrow Alert me when eLetters are posted
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow Request Copyright Permission
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Bernini, G.
Right arrow Articles by Salvetti, A.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Bernini, G.
Right arrow Articles by Salvetti, A.
Related Collections
Right arrow Cardiovascular Endocrinology
Right arrow Male Endocrinology

HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Endocrinology Endocrine Reviews J. Clin. End. & Metab.
Molecular Endocrinology Recent Prog. Horm. Res. All Endocrine Journals