Journal of Clinical Endocrinology & Metabolism, Vol 78, 433-439, Copyright © 1994 by Endocrine Society

ARTICLES

Human follicular fluid contains pro- and C-terminal immunoreactive alpha-inhibin precursor proteins

GM Lambert-Messerlian, K Isaacson, WF Crowley Jr, P Sluss and AL Schneyer
Department of Medicine, Massachusetts General Hospital, Boston 02114.

The majority of immunoactive inhibin in human follicular fluid (hFF) is devoid of pituitary cell bioactivity and is hypothesized to contain alpha-inhibin monomeric proteins known to cross-react with an inhibin antiserum (Monash 1989). The aim of this study was to define more precisely the nature of these inhibin-immunoreactive proteins using alpha-inhibin sequence-specific antisera. First, a polyclonal antiserum was raised to precursor amino acids 21-35 (PIN-1) and was used in a RIA to measure pro-alpha-inhibin-immunoreactive proteins. Western blotting was used to confirm these findings. Secondly, the binding epitope of the Monash antiserum was defined by peptide analysis to be located within the C-terminus (precursor amino acids 326-341) of alpha-inhibin, and this assay was then used to monitor the presence of C-terminal sequences. Similar levels of pro-alpha-inhibin immunoreactivity (PIN-1 RIA; N-terminus alpha-inhibin precursor) were detected in hFF collected from women with normal menstrual cycles during the follicular phase and from multiple follicles from a woman undergoing ovarian hyperstimulation during an in vitro fertilization (IVF) protocol. Western blotting with the PIN-1 antibody confirmed the presence of immunoreactive proteins of 57,000 and 29,000 mol wt in the follicular fluids of both normal cycle and IVF follicles. However, ovarian hyperstimulation elevated intrafollicular C-terminal immunoreactivity (Monash RIA) compared to that in normal cycle hFF. Furthermore, intrafollicular estradiol and progesterone were significantly correlated to C-terminal activity in follicles from IVF, but not in normal cycles. These data show that 1) both pro- and C-terminal alpha- inhibin proteins are secreted into follicular fluids from normal and IVF cycles, suggesting that alpha-inhibin precursor proteins may be physiologically relevant in the process of folliculogenesis; and 2) IVF and normal cycle follicular fluids differ in their production and processing of inhibin.

This article has been cited by other articles:

				C. Cariou-Guennoc, J.C. Poirier, B. Calas, A. Locatelli, J.L. Dacheux, and M.R. Blanc Evidence That Luteinizing Hormone-Releasing Hormone Statin from Ovine Rete Testis Fluid Is Immunologically Related to {alpha}C Inhibin Biol Reprod, June 1, 2000; 62(6): 1551 - 1563. [Abstract] [Full Text]

				K. Nagaoka, Y. Nambo, N. Nagamine, S.-I. Nagata, Y. Tanaka, H. Shinbo, N. Tsunoda, H. Taniyama, G. Watanabe, N. P. Groome, et al. A selective increase in circulating inhibin and inhibin pro-alpha C at the time of ovulation in the mare Am J Physiol Endocrinol Metab, November 1, 1999; 277(5): E870 - E875. [Abstract] [Full Text] [PDF]

				L. Poretsky, N. A. Cataldo, Z. Rosenwaks, and L. C. Giudice The Insulin-Related Ovarian Regulatory System in Health and Disease Endocr. Rev., August 1, 1999; 20(4): 535 - 582. [Abstract] [Full Text] [PDF]

				F. J. Hayes, J. E. Hall, P. A. Boepple, and W. F. Crowley Jr. Differential Control of Gonadotropin Secretion in the Human: Endocrine Role of Inhibin J. Clin. Endocrinol. Metab., June 1, 1998; 83(6): 1835 - 1841. [Full Text]

				C. K. Welt, G. Lambert-Messerlian, W. Zheng, W. F. Crowley Jr., and A. L. Schneyer Presence of Activin, Inhibin, and Follistatin in Epithelial Ovarian Carcinoma J. Clin. Endocrinol. Metab., November 1, 1997; 82(11): 3720 - 3727. [Abstract] [Full Text] [PDF]

				E. M. Wallace, N. P. Groome, S. C. Riley, A. C. Parker, and F. C. W. Wu Effects of Chemotherapy-Induced Testicular Damage on Inhibin, Gonadotropin, and Testosterone Secretion: A Prospective Longitudinal Study J. Clin. Endocrinol. Metab., September 1, 1997; 82(9): 3111 - 3115. [Abstract] [Full Text] [PDF]

				D. M. Robertson, N. Cahir, J. K. Findlay, H. G. Burger, and N. Groome The Biological and Immunological Characterization of Inhibin A and B Forms in Human Follicular Fluid and Plasma J. Clin. Endocrinol. Metab., March 1, 1997; 82(3): 889 - 896. [Abstract] [Full Text] [PDF]