A developmental study of the gonadotropin-releasing hormone neuronal system during sexual maturation in the male Djungarian hamster.
The number, morphology, and distribution of gonadotropin-releasing hormone cell bodies were studied in the brain of the male Djungarian hamster during sexual maturation. Males were reared in long days (16L:8D) and were killed at 15, 25, or 40 days of age, before (n = 5), during (n = 4), or after puberty (n = 4), respectively. Brain sections (60 microns) from the rostral olfactory tubercle to the medial basal hypothalamus were processed for GnRH immunocytochemistry. Unipolar and bipolar neurons were immunolabeled for GnRH; both subtypes had smooth cell contours. Analysis of every section from the olfactory tubercle to the arcuate nucleus indicated that at all ages more than 75% of all GnRH-immunoreactive cell bodies were distributed in the diagonal band of Broca, medial preoptic area, lateral preoptic area, and lateral hypothalamic area. GnRH-positive somata were also found in other brain regions, but in each of these areas they represented less than 6% of the total GnRH neuron number. In peripubertal 25-day-old males, during the rapid phase of testes growth, the number of unipolar, but not bipolar, GnRH-labeled cells nearly doubled in the diagonal band of Broca compared to soma numbers in this location in prepubertal 15-day-old males. The same number of unipolar GnRH-stained somata were found in this region in 40-day-old as in 25-day-old hamsters. In the medial preoptic area, a similar doubling of unipolar neuron numbers was observed at 25 days, but by 40 days the number of unipolar immunostained GnRH cells was secondarily reduced to a level comparable to that at 15 days.(ABSTRACT TRUNCATED AT 250 WORDS)
Yellon
S M
SM
Department of Physiology, Loma Linda University School of Medicine, California 92350.
Newman
S W
SW
D000375:Aging / Q000502:physiology; D000818:Animals; D001921:Brain / Q000166:cytology / Q000254:growth & development*; D002452:Cell Count; D006224:Cricetinae; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism*; D008297:Male; D009474:Neurons / Q000166:cytology*; D011301:Preoptic Area / Q000166:cytology / Q000254:growth & development; D012741:Sexual Maturation / Q000502:physiology*; D013737:Testis / Q000254:growth & development
D007987:Gonadotropin-Releasing Hormone