Hormonal modification of the number of total and late-arising neurons in the central part of the medial preoptic nucleus of the rat.
The sexually dimorphic nucleus of the preoptic area (SDN-POA) is larger in volume in males, is responsive to steroids developmentally, and contains a subpopulation of late-arising neurons that can be specifically labeled with 3H-thymidine on embryonic day 18 (E18). The cytoarchitecture of this region has been described, and one component, the central part of the medial preoptic nucleus (MPNc), shows considerable overlap with the SDN-POA. One goal of the present study was to relate the two by determining if testosterone propionate (TP) exposure perinatally increases MPNc volume and neuronal number, and by characterizing the distribution of the late arising neurons of the SDN-POA with respect to the MPNc. A second goal was to determine if these late-arising neurons are a representative, hormone-sensitive population. Finally, TP exposure was delayed past the time of the endogenous testosterone surge in males and after the neurons have become postmitotic, to determine if female brain structure could still be sex-reversed under these conditions. Pregnant rats were injected on E18 with 3H-thymidine. Daily injections of 2.0 mg TP were given to the mothers starting on either E16 or E20 and continued through birth. The pups were injected daily with 100 micrograms TP from birth through postnatal day 10. Control rats, from mothers given oil from E16 until birth, were injected with oil from birth through postnatal day 10. Rats were sacrificed at 30 days of age and their brains processed for autoradiography.(ABSTRACT TRUNCATED AT 250 WORDS)
Dodson
R E
RE
Department of Anatomy, UCLA School of Medicine 90024.
Shryne
J E
JE
Gorski
R A
RA
D000375:Aging / Q000502:physiology*; D000818:Animals; D002452:Cell Count; D005314:Embryonic and Fetal Development / Q000187:drug effects*; D005260:Female; D008297:Male; D009929:Organ Size; D011301:Preoptic Area / Q000196:embryology / Q000254:growth & development* / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D013739:Testosterone / Q000494:pharmacology*; D013936:Thymidine
D013739:Testosterone; D013936:Thymidine