This Article Abstract Full Text (PDF) Submit a related Letter to the Editor Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Kolaczynski, J. W. Articles by Considine, R. V. Search for Related Content PubMed PubMed Citation Articles by Kolaczynski, J. W. Articles by Considine, R. V. Pubmed/NCBI databases Compound via MeSH Substance via MeSH Hazardous Substances DB DEXAMETHASONE Medline Plus Health Information Obesity

Dexamethasone, OB Gene, and Leptin in Humans; Effect of Exogenous Hyperinsulinemia¹

Division of Endocrinology, Diabetes and Metabolic Diseases, Thomas Jefferson University (J.W.K., B.J.G.), Philadelphia, Pennsylvania 19107; and University of Indiana Medical Center (R.V.C.), Indianapolis, Indiana

Address all correspondence and requests for reprints to: Jerzy W. Kolaczynski, Division of Endocrinology, Diabetes and Metabolic Diseases, Thomas Jefferson University, 211 South 9th Street, Suite 600, Philadelphia, Pennsylvania 19107.

	Abstract

Top Abstract Introduction Materials and Methods Results Discussion References

 
This study was undertaken to investigate temporal association between dexamethasone administration, OB gene expression, and leptin response in humans in the presence and absence of exogenous hyperinsulinemia. Six healthy males (age 24.5 ± 1.0 yr, body mass index 26.4 ± 1.0, body fat 16.2 ± 1.8%) received 10 mg oral dexamethasone in five divided doses twice (protocols A and B) 1–2 weeks apart beginning at 0800 h on day 1 and ending at 0700 h on day 2. The dexamethasone administration was combined with two subcutaneous abdominal fat biopsies performed at 0800 h before and after dexamethasone administration (protocol A), or 4-h isoglycemic hyperinsulinemic (300 mU/m² BSA/min, protocol B) clamp carried out between 0900 and 1300 h on day 2. OB gene expression (protocol A) did not change. In both protocols on day 2, the 0800 h leptin levels nearly doubled (P < 0.001), whereas 1300 h levels nearly quadrupled (P < 0.001). The elevation in leptin persisted until 0800 h of day 3 (24 h after last dexamethasone dose) with its subsequent rapid normalization. The short-term isoglycemic hyperinsulinemia (protocol B) had no additional effect on the postdexamethasone leptin response. We summarize that: 1) 24-h administration of dexamethasone has a marked stimulatory effect on circulating leptin levels but not on OB gene expression in the subcutaneous abdominal fat. 2) The effect is sustained for the next 24 h. 3) Short-term hyperinsulinemia has no additional effect. We conclude that dexamethasone is a powerful stimulator of leptin production in vivo through a mechanism that appears to be independent of OB gene transcription in the human subcutaneous abdominal fat.

	Introduction

Top Abstract Introduction Materials and Methods Results Discussion References

 
THE CIRCULATING levels of the recently discovered adipose tissue hormone leptin have been shown in humans to have a dual regulation (1, 2, 3). Under normal feeding conditions, the daytime leptin levels demonstrate good correlation with body fat mass (4). In contrast, at the extremes of the energy balance, fasting and massive overfeeding, leptin levels are down- and up-regulated independently of the fat mass (2, 3). Leptin levels in humans can also be modified by administration of dexamethasone (5, 6, 7), troglitazone (8), and insulin (9, 10). We also have shown temporal differences in the stimulatory effects of dexamethasone and insulin on OB gene expression and leptin release in vitro (9, 10), which suggests involvement of different regulatory pathways. We also recently observed that in vitro insulin can completely block the dexamethasone-stimulated increase in leptin release (10). The relevance of these findings to the in vivo setting is unknown. In the recent report, administration of pharmacological doses of dexamethasone for 48 h resulted in doubling of the fasting leptin levels (7), irrespective of the degree of the dexamethasone-induced hyperinsulinemia. No data, however, are available regarding dexamethasone effect on OB gene expression in humans in vivo, and the temporal association between dexamethasone administration and the pattern and duration of the circulating leptin response. Consequently, we studied the effect of dexamethasone on OB gene and the pattern of leptin rise and recovery during and after dexamethasone administration. In addition, we examined whether short-term supraphysiological exogenous hyperinsulinemia alters the circulating leptin response after dexamethasone.

	Materials and Methods

Top Abstract Introduction Materials and Methods Results Discussion References

 
Six healthy, young (age 24.5 ± 1.0 yr), nonobese (body mass index 26.4 ± 1.0 kg/m², body fat 16.2 + 1.8%) males participated in two 3-day protocols (A and B) set 1–2 weeks apart, in a random order. In each protocol, they ingested five 2.0-mg oral doses of dexamethasone (Roxane Laboratories, Columbus, OH) at 0800, 1200, 1800, 2400 h on day 1 and at 0700 h on day 2. In protocol A, two biopsies of subcutaneous abdominal fat (11) were obtained from five participants (each at 0800 h), the first 24–72 h before dexamethasone, and the second on day 2. In protocol B, the dexamethasone intake was combined with isoglycemic hyperinsulinemic clamp (9) (Humulin R, Eli Lilly, Indianapolis, IN) at primed constant rate of 300 mU/m² BSA/min commencing at 0900 and ending at 1300 h on day 2. During the entire study, the subjects were allowed to maintain their normal diet and lifestyle except for drinking of alcohol and indulgence in moderate to heavy bouts of physical activity (training sessions at a gym in three subjects and rugby practices in the remaining three subjects) to avoid interference of stress reactions induced by severe exertion, injuries, and inebration. The nature and purpose of the studies was carefully explained to all the participants, and they signed a written informed consent approved by Institutional Review Board of the Thomas Jefferson University, Philadelphia, PA.

Measurements

Fat mass was assessed by bioelectric impedance analysis (RJL Systems, Mt. Clemens, MI; Ref.12) and skinfold measurements, and the two values, all falling within ±4% variance, were averaged. Blood samples for measurements of leptin, insulin, and glucose were obtained at 0800 and 1300 h on each day (1st through 3rd) of protocols A and B, and additionally every 5 (for glucose) and 30 min during the clamp (protocol B). Plasma glucose was determined with Beckman II Glucose Analysis (Brea, CA); serum insulin and leptin were determined by kits purchased from Linco Research (St. Charles, MO).

OB gene messenger RNA (mRNA) was measured in the adipose tissue by RT-PCR as previously reported (4).

The results are presented as individuals’ values (means ± SE). The statistical analysis was performed on raw and logarithmically transformed data, with ANOVA and Student’s t test where applicable.

	Results

Top Abstract Introduction Materials and Methods Results Discussion References

 
Figure 1 illustrates responses of leptin during and after dexamethasone intake. In both protocols, the initial doses of the drug did not produce any change in circulating leptin levels. In fact, leptin tended to decline between 0800 and 1300 h on day 1 (Table 1; P = 0.1). In contrast in both protocols, on day 2 at 0800 and 1300 h (i.e. 1 h after the last dose of dexamethasone) leptin levels nearly doubled (P < 0.001) and quadrupled (P < 0.001), respectively, compared with the respective values of day 1 (Table 1). The elevation persisted until 0800 h on day 3 with subsequent rapid decline at 1300 h.

View larger version (19K): [in this window] [in a new window]   Figure 1. Circulating leptin levels during and after administration of 10 mg dexamethasone in five divided doses (arrows) over first 24 h of study in absence (, protocol A; n = 6) and presence (•, protocol B; n = 6) of short-term supraphysiological insulinemia (isoglycemic clamp carried out between 0900 and 1300 h on day 2).

View larger version (21K): [in this window] [in a new window]   Figure 2. OB gene expression and corresponding circulating leptin levels at 0800 h before and after dexamethasone (protocol A; n = 5).

	Discussion

Top Abstract Introduction Materials and Methods Results Discussion References

 
This study extends our previous observations on interaction of insulin and dexamethasone of OB gene expression and leptin production by the human subcutaneous abdominal fat (10), and confirms the published observations that pharmacological doses of dexamethasone have a significant stimulatory effect of the circulating leptin levels in humans (5, 6, 7). The major finding of the present study is the illustration of the temporal relationship between dexamethasone intake and subsequent duration and magnitude of leptin change. Interestingly, the observed leptin elevation occurred without elevation in OB gene expression in the subcutaneous abdominal fat.

In our previous experiments in vitro on adipocytes in primary culture isolated from human subcutaneous abdominal fat, dexamethasone consistently increased the OB gene expression and leptin release to the medium (10). The elevation was first notable after first 24 h incubation with dexamethasone. In contrast, coincubation of dexamethasone with insulin abrogated the effect of dexamethasone in a dose-dependent manner (10). Our present data do not provide evidence for existence of such antagonism in vivo, even though we tested it in two different ways. First, we looked at whether rising endogenous insulin in response to dexamethasone-induced insulin resistance would diminish the leptin’s response, and we failed to find any association. Secondly, the exposure to approximately 150 U of exogenous insulin infused over 4 h, under isoglycemic conditions, at the time when leptin levels were rising at the highest rate (between 0900 and 1300 h on day 2) did not escalate this elevation nor change the length of time when leptin levels remained elevated (until 0800 h on day 3).

Somewhat unexpected was the finding of unchanged OB gene expression in the presence of a rapid leptin rise. We previously observed similar phenomenon in our fasting experiments when 80% down-regulation in leptin levels produced minimal change in OB gene mRNA in the human subcutaneous abdominal fat (1). Several explanations can be offered. First, acute changes in leptin production in the human fat are either regulated through changes in OB gene mRNA stability or at the translational level. Second, the acute changes in leptin levels are due to up- or down-regulation of OB gene in fat depots different than subcutaneous abdominal. Third, the primary mechanism is altered leptin clearance from the circulation. In addition, the discrepancy in the in vivo and in vitro effect of dexamethasone on OB gene raises the possibility that both neural and humoral factors present in the intact adipose tissue and absent in the in vitro setting are playing a significant role in the control of the gene activity.

In summary, our data document that dexamethasone at pharmacological doses is a powerful stimulator of circulating leptin levels. The effect is sustained for the next 24 h. Short-term hyperinsulinemia does not change the pattern of the observed leptin rise and recovery. We conclude that dexamethasone is a powerful stimulator of leptin production in vivo through a mechanism that may be independent of OB gene transcription in the human subcutaneous abdominal fat.

	Acknowledgments

 
We greatly appreciate the technical help of Irina Opentanova.

	Footnotes

 
¹ This work was supported by Grants: RO1-DK45592 and R29 DK5114.

Received May 21, 1997.

Revised July 11, 1997.

Accepted July 21, 1997.

	References

Top Abstract Introduction Materials and Methods Results Discussion References

 

1. Kolaczynski JW, Considine RV, Ohannesian J, et al. 1996 Responses of leptin to short-term fasting and refeeding in humans: a link with ketogenesis but not ketones themselves. Diabetes. 45:1511–1515.[Abstract]
2. Kolaczynski JW, Ohannesian J, Considine RV, Marco C, Caro JF. 1996 Response of leptin to short term and prolonged overfeeding in humans. J Clin Endo Metab. 81:4162–4165.[Abstract/Free Full Text]
3. Caro JF, Considine RV, Sinha MK, Kolaczynski JW, Zhang P, Considine RV. 1996 Leptin: the tale of human obesity gene. Diabetes. 45:1455–1462.[Medline]
4. Considine RV, Sinha MK, Heiman ML, et al. 1996 Serum immunoreactive leptin concentrations in normal-weight and obese humans. N Engl J Med. 334:292–295.[Abstract/Free Full Text]
5. Miell SP, Englaro P, Blum WT. 1996 Dexamethasone induces an acute and sustained rise in circulating leptin levels in normal human subjects. Horm Metab Res. 28:704–707.[Medline]
6. Klein W, Englaro P, Hanitsch S, Rasler W, Attanasio A, Blum WF. 1996 High leptin concentrations in serum of very obese children are further stimulated by dexamethasone. Horm Metab Res. 28:708–710.[Medline]
7. Larsson H, Ahren B. 1996 Short-term dexamethasone treatment increases plasma leptin independently of changes in insulin sensitivity in healthy women. J Clin Endocrinol Metab. 81:4428–4432.[Abstract]
8. Nolan JJ, Olefsky JM, Nyce MR, Considine RV, Caro JF. 1996 Effect of troglitazone on leptin production—studies in vitro and in human subjects. Diabetes. 45:1276–1278.[Abstract]
9. Kolaczynski JW, Nyce MR, Considine RV, et al. 1996 Acute and chronic effect of insulin on leptin production in humans: studies in vivo and in vitro. Diabetes. 45:699–701.[Abstract]
10. Considine RV, Nyce MR, Kolaczynski JW, et al. 1997 Dexamethasone stimulates leptin release from human adipocytes: unexpected inhibition by insulin. J Cell Biochem. 64:254–258.
11. Kolaczynski JW, Moralez LM, Moore JH, Considine RV, Pietrzkowski Z, Caro JF. A new technique for biopsy of human abdominal fat under local anesthesia with lidocaine. Int J Obes. 18:161–166:1994.
12. Lukaski HC, Johnson PE, Bolonchuk WW, Lykken GI. 1985 Assessment of fat free mass using bioelectrical impedance measurements of the human body. Am J Clin Nutr. 41:810–817.[Abstract/Free Full Text]

This article has been cited by other articles:

				H. Muller, N. Schweitzer, O. Johren, P. Dominiak, and W. Raasch Angiotensin II stimulates the reactivity of the pituitary-adrenal axis in leptin-resistant Zucker rats, thereby influencing the glucose utilization Am J Physiol Endocrinol Metab, September 1, 2007; 293(3): E802 - E810. [Abstract] [Full Text] [PDF]

				M J Moreno-Aliaga, M M Swarbrick, S Lorente-Cebrian, K L Stanhope, P J Havel, and J A Martinez Sp1-mediated transcription is involved in the induction of leptin by insulin-stimulated glucose metabolism J. Mol. Endocrinol., May 1, 2007; 38(5): 537 - 546. [Abstract] [Full Text] [PDF]

				G. E. Sonnenberg, G. R. Krakower, R. G. Hoffmann, D. L. Maas, M. M. I. Hennes, and A. H. Kissebah Plasma Leptin Concentrations during Extended Fasting and Graded Glucose Infusions: Relationships with Changes in Glucose, Insulin, and FFA J. Clin. Endocrinol. Metab., October 1, 2001; 86(10): 4895 - 4900. [Abstract] [Full Text] [PDF]

				S. K. Fried, M. R. Ricci, C. D. Russell, and B. Laferrere Regulation of Leptin Production in Humans J. Nutr., December 1, 2000; 130 (12): 3127S - 3131S. [Abstract] [Full Text] [PDF]

				P C Ng, C W K Lam, C H Lee, G W K Wong, T F Fok, E Wong, K C Ma, and I H S Chan Leptin and metabolic hormones in infants of diabetic mothers Arch. Dis. Child. Fetal Neonatal Ed., November 1, 2000; 83(3): 193F - 197. [Abstract] [Full Text]

				R. V. Considine, R. C. Cooksey, L. B. Williams, R. L. Fawcett, P. Zhang, W. T. Ambrosius, R. M. Whitfield, R. Jones, M. Inman, J. Huse, et al. Hexosamines Regulate Leptin Production in Human Subcutaneous Adipocytes J. Clin. Endocrinol. Metab., October 1, 2000; 85(10): 3551 - 3556. [Abstract] [Full Text]

				L. B. Williams, R. L. Fawcett, A. S. Waechter, P. Zhang, B. E. Kogon, R. Jones, M. Inman, J. Huse, and R. V. Considine Leptin Production in Adipocytes from Morbidly Obese Subjects: Stimulation by Dexamethasone, Inhibition with Troglitazone, and Influence of Gender J. Clin. Endocrinol. Metab., August 1, 2000; 85(8): 2678 - 2684. [Abstract] [Full Text]

				F. S. L. Thong, R. Hudson, R. Ross, I. Janssen, and T. E. Graham Plasma leptin in moderately obese men: independent effects of weight loss and aerobic exercise Am J Physiol Endocrinol Metab, August 1, 2000; 279(2): E307 - E313. [Abstract] [Full Text] [PDF]

				T. Hytinantti, H. A Koistinen, V. A Koivisto, S.-L. Karonen, E.-M. Rutanen, S. Andersson;, A. BEREZIN, and M. MELO Increased leptin concentration in preterm infants of pre-eclamptic mothers Arch. Dis. Child. Fetal Neonatal Ed., July 1, 2000; 83(1): 13F - 16. [Abstract] [Full Text]

				J. Q. Purnell and M. H. Samuels Levels of Leptin during Hydrocortisone Infusions that Mimic Normal and Reversed Diurnal Cortisol Levels in Subjects with Adrenal Insufficiency J. Clin. Endocrinol. Metab., September 1, 1999; 84(9): 3125 - 3128. [Abstract] [Full Text]

				L. I. McKay and J. A. Cidlowski Molecular Control of Immune/Inflammatory Responses: Interactions Between Nuclear Factor-{kappa}B and Steroid Receptor-Signaling Pathways Endocr. Rev., August 1, 1999; 20(4): 435 - 459. [Abstract] [Full Text] [PDF]

				H. H. Zhang, S. Kumar, A. H. Barnett, and M. C. Eggo Intrinsic Site-Specific Differences in the Expression of Leptin in Human Adipocytes and Its Autocrine Effects on Glucose Uptake J. Clin. Endocrinol. Metab., July 1, 1999; 84(7): 2550 - 2556. [Abstract] [Full Text]

				C. D. Russell, R. N. Petersen, S. P. Rao, M. R. Ricci, A. Prasad, Y. Zhang, R. E. Brolin, and S. K. Fried Leptin expression in adipose tissue from obese humans: depot-specific regulation by insulin and dexamethasone Am J Physiol Endocrinol Metab, September 1, 1998; 275(3): E507 - E515. [Abstract] [Full Text] [PDF]

				D. Torpy, S. Bornstein, G Cizza, and G. Chrousos The Effects of Glucocorticoids on Leptin Levels in Humans May Be Restricted to Acute Pharmacologic Dosinga J. Clin. Endocrinol. Metab., May 1, 1998; 83(5): 1821 - 1822. [Full Text]

				J. W. Kolaczynski Dexamethasone, OB Gene, and Leptin in Humans: Effect of Exogenous Hyperinsulinemia--Author's Responseb J. Clin. Endocrinol. Metab., May 1, 1998; 83(5): 1822 - 1822. [Full Text]

				P. J. Havel, J. Y. Uriu-Hare, T. Liu, K. L. Stanhope, J. S. Stern, C. L. Keen, and B. Ahren Marked and rapid decreases of circulating leptin in streptozotocin diabetic rats: reversal by insulin Am J Physiol Regulatory Integrative Comp Physiol, May 1, 1998; 274(5): R1482 - R1491. [Abstract] [Full Text] [PDF]

This Article Abstract Full Text (PDF) Submit a related Letter to the Editor Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Kolaczynski, J. W. Articles by Considine, R. V. Search for Related Content PubMed PubMed Citation Articles by Kolaczynski, J. W. Articles by Considine, R. V. Pubmed/NCBI databases Compound via MeSH Substance via MeSH Hazardous Substances DB DEXAMETHASONE Medline Plus Health Information Obesity