Hypothalamic regulation of the adenohypophyseal-testicular axis in the male chick embryo.
An antibody against luteinizing hormone-releasing hormone (LHRH) as well as naloxone, an opioid antagonist, were added to the chorioallantoic membrane (CAM) of 11.5- and 14.5-day-old male chick embryos and plasma testosterone (T) concentrations were determined. This protocol was designed to demonstrate: (1) Whether LHRH is essential in the regulation of the adenohypophyseal-testicular axis in the male embryo and (2) if LHRH is operative in this unit's function, are opiatergic pathways involved in the secretion of LHRH by the hypothalamus. Both anti-LHRH and naloxone lowered plasma T levels in 14.5-day-old embryos, but not 11.5-day-old embryos. This indicates that the hypothalamus, via LHRH, begins to regulate the pituitary-testicular unit at some time between Days 11.5 and 14.5, i.e., the hypothalamo-adenohypophyseal-testicular axis is established. The results also strongly suggest that the normal secretory pattern of LHRH is dependent upon opiatergic innervation of the hypothalamus at the same embryonic time.
Woods
J E
JE
College of Liberal Arts and Sciences, De Paul University, Chicago, Illinois 60614.
Honan
M P
MP
Thommes
R C
RC
D000482:Allantois; D000818:Animals; D000906:Antibodies / Q000008:administration & dosage; D002642:Chick Embryo / Q000502:physiology*; D007987:Gonadotropin-Releasing Hormone / Q000276:immunology / Q000502:physiology*; D007031:Hypothalamus / Q000502:physiology*; D008297:Male; D009270:Naloxone / Q000494:pharmacology; D010903:Pituitary Gland, Anterior / Q000502:physiology*; D013737:Testis / Q000502:physiology*; D013739:Testosterone / Q000097:blood; D013997:Time Factors
D000906:Antibodies; D007987:Gonadotropin-Releasing Hormone; D009270:Naloxone; D013739:Testosterone