HOME HELP CONTACT US SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Almeida, O. F. X. Articles by Martin, G. B. Search for Related Content PubMed Articles by Almeida, O. F. X. Articles by Martin, G. B.

It was found in previous studies that the neurotransmitter control of the secretion of LHRH and LH differs between long-term castrated and ovariectomized rats. One interpretation of these data was that there was a reduced 'positive drive' in the male, and the question was raised 'how do the gonadotrophs of long-term castrated rats maintain a high level of LH secretion?'. In the present series of experiments, evidence for a reduced dependence of the gonadotrophs upon LHRH stimulation is provided. Although sensitivity to native LHRH was not completely lost in long-term castrated rats, two potent LHRH antagonists (D-pyroglu¹,D-Phe²,D-Trp^3,6)-LHRH and (N-acetyl-3,4-dehydro-Pro,p-fluoro-D-Phe²,D-Trp^3,6)-LHRH, were found to inhibit LH secretion in short-term castrated and long-term ovariectomized rats, but not in long-term castrated rats. Neither blockade of axonal transport with colchicine nor immunoneutralization of LHRH with an antiserum against LHRH (both administered 48 h before blood sampling) produced reductions in serum concentrations of LH in long-term castrated rats, although these treatments significantly suppressed LH levels in short-term castrated animals. Chronic (6-day) infusions of the second LHRH antagonist (up to 450 µg/day) neither reduced LH secretion nor altered the morphology of the 'castration cells' in the pituitaries of long-term castrated rats. Chronic treatment with testosterone (15 days), however, reversed these parameters to some extent, and when the testosterone treatment was coupled with chronic infusions of the LHRH antagonist, significantly lower serum levels of LH and reductions in the size of the castration cells were observed. These data thus indicate that castration cells may function autonomously, without the need for LHRH, and that testosterone in some way restores the dependency on LHRH and/or the responsiveness to LHRH of these cells.

Journal of Endocrinology (1989) 123, 263–273

This article has been cited by other articles:

				L A Nolan and A Levy The effects of testosterone and oestrogen on gonadectomised and intact male rat anterior pituitary mitotic and apoptotic activity. J. Endocrinol., March 1, 2006; 188(3): 387 - 396. [Abstract] [Full Text] [PDF]

				R. M. David, M. R. Moore, D. C. Finney, and D. Guest Chronic Toxicity of Di(2-ethylhexyl)phthalate in Rats Toxicol. Sci., June 1, 2000; 55(2): 433 - 443. [Abstract] [Full Text] [PDF]

				V. A. Tobin, R. P. Millar, and B. J. Canny Testosterone Acts Directly at the Pituitary to Regulate Gonadotropin-Releasing Hormone-Induced Calcium Signals in Male Rat Gonadotropes Endocrinology, August 1, 1997; 138(8): 3314 - 3319. [Abstract] [Full Text] [PDF]