scholarly journals Plasma Luteinizing Hormone Response to Increasing doses of Synthetic Gonadotrophin-Releasing Hormone in Heifers

1983 ◽  
Vol 24 (2) ◽  
pp. 211-224
Author(s):  
A. Mikél Jensen ◽  
K. Myrup Pedersen ◽  
J. F. Agger ◽  
A. Madej
1995 ◽  
Vol 132 (6) ◽  
pp. 663-667 ◽  
Author(s):  
Eva Marie T Erfurth ◽  
Lars E Hagmar

Erfurth EMT, Hagmar LE. Decreased serum testosterone and free triidothyronine levels in healthy middle-aged men indicate an age effect at the pituitary level. Eur J Endocrinol 1995;132:663–7. ISSN 0804–4643 In an attempt to study further the age-specific influence on the hypothalamo-pituitary–gonadal axis as well as the hypothalamo–pituitary–thyroid axis, we have now investigated young and middle-aged men, considering possible confounding factors. Both serum total testosterone, free testosterone and the total ratio of testosterone to sex-hormone binding globulin were significantly lower among middle-aged men as compared with young men (p = 0.02, p = 0.002 and p = 0.0003, respectively). In accordance with these findings there was also a decrease in the luteinizing hormone response to gonadotrophin-releasing hormone in the middle-aged men (p= 0.02). Free testosterone was correlated significantly with the luteinizing hormone response (r = 0.32, p = 0.02). Serum free triiodothyronine was significantly higher among young men as compared with middle-aged men (p = 0.002) and the thyrotrophin-releasing hormone-stimulated thyrotrophin response was also higher in the young group compared with the middle-aged group. The present results may indicate that the age effect on serum levels of testosterone and free triidothyronine is mediated at the pituitary level. Eva Marie Erfurth, Dept. of Internal Medicine, University of Lund, S-221 85 Lund, Sweden


2013 ◽  
pp. 551-566
Author(s):  
John Reynard ◽  
Simon Brewster ◽  
Suzanne Biers

Male reproductive physiology 552 Aetiology and evaluation of male infertility 554 Investigation of male infertility 556 Oligozoospermia and azoospermia 560 Varicocele 562 Treatment options for male infertility 564 The hypothalamus secretes luteinizing hormone-releasing hormone (LHRH), also known as gonadotrophin-releasing hormone (GnRH). This causes the pulsatile release of anterior pituitary gonadotrophins called follicle-stimulating hormone (FSH) and luteinizing hormone (LH), which act on the testis. FSH stimulates the seminiferous tubules to secrete inhibin and produce sperm; LH acts on Leydig cells to produce testosterone (...


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