Differential distribution and response to experimental sexual maturation of two forms of brain gonadotropin-releasing hormone (GnRH) in the European eel, Anguilla anguilla

1993 ◽  
Vol 11 (1-6) ◽  
pp. 99-106 ◽  
Author(s):  
Sylvie Dufour ◽  
Maïté Montero ◽  
Nadine Le Belle ◽  
Marc Bassompierre ◽  
Judy A. King ◽  
...  
Keyword(s):  
Sexual Maturation ◽  
Anguilla Anguilla ◽  
Gonadotropin Releasing Hormone ◽  
European Eel ◽  
Differential Distribution ◽  
Releasing Hormone

Pituitary and gonadal responsiveness is enhanced during GnRH-induced puberty

1988 ◽  
Vol 254 (5) ◽  
pp. E652-E657
Author(s):  
D. I. Spratt ◽  
W. F. Crowley
Keyword(s):  
Luteinizing Hormone ◽  
Sexual Maturation ◽  
Sexual Development ◽  
Follicle Stimulating Hormone ◽  
Gonadotropin Releasing Hormone ◽  
Releasing Hormone ◽  
Hormone Levels ◽  
Gnrh Secretion ◽  
Serum Luteinizing Hormone ◽  
Before And After

We hypothesized that the hypothalamic gonadotropin-releasing hormone (GnRH) signal that initiates sexual maturation is further amplified at both the pituitary and gonadal levels during puberty. To test this theory, six GnRH-deficient men were monitored during administration of exogenous GnRH at a physiological frequency for greater than or equal to 9 mo. GnRH doses were progressively increased until normal testosterone (T) concentrations and secondary sexual development were achieved. This "optimized" dose of GnRH was then sustained for at least 6 mo to allow maturation of the hypothalamic-pituitary-gonadal axis. The GnRH dose was then progressively decreased to a level that had been unable to stimulate normal T secretion before sexual maturation. Changes in pituitary responsiveness were analyzed in four of the six men by comparing gonadotropin responses to identical doses of GnRH before and after sexual maturation. Mean serum luteinizing hormone and follicle-stimulating hormone levels as well as luteinizing hormone pulse amplitudes were greater after the induction of sexual maturation than before despite identical doses of GnRH. Both pituitary and gonadal responsiveness was then analyzed in the remaining two subjects by choosing periods of evaluation where endogenous gonadotropin levels were matched before and after the period of sexual maturation. Serum T concentrations were greater after sexual maturation than before despite equivalent gonadotropin input to the testes and LH pulse amplitudes. Thus the testicular responsiveness to gonadotropins increased during sexual maturation. After initiation of puberty by GnRH secretion, amplification at both the pituitary and gonadal levels contributes to sexual maturation in the human.

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