Sex difference and steroidal stimulation of galanin immunoreactivity in the ferret's dorsal preoptic area/anterior hypothalamus.
A sexually dimorphic male nucleus (MN) is seen in Nissl-stained sections from the dorsal preoptic area/anterior hypothalamus (dPOA/AH) of male, but not female, ferrets. We used immunohistochemical methods to determine whether particular neuropeptides are found in cells of the MN. A sexually dimorphic cluster of galanin-immunoreactive (IR) cells was found in the dPOA/AH of ferrets killed either on embryonic day (E) 38 or in adulthood. Significantly more galanin-IR cells were distributed in the MN and in other subregions of the dPOA/AH of intact breeding males than estrous females. The density of galanin-IR cells in the dPOA/AH was significantly reduced in adult males by castration and restored to the level of intact breeding males by daily injections of testosterone propionate (TP) for 5 weeks. The same TP treatment failed to augment the density of galanin-IR cells in the dPOA/AH of adult, ovariectomized females. Computer-assisted image analysis and grid-crossing analysis showed that the area and the number of galanin-IR fibers in the dPOA/AH were significantly greater in adult females than in males, regardless of subjects' concurrent steroidal condition. A cluster of galanin-IR cells was present in the dPOA/AH of males, but not females, killed on either E34 or E38. Administration of TP between E28 and E37 significantly increased the density of galanin-IR cells in the dPOA/AH of females killed on E38, up to the level seen in control males. The results suggest that the capacity of cells located in the dPOA/AH to express galanin after adult steroid exposure is sexually differentiated by the fetal action of testosterone, or its metabolite, estradiol, in males.
Park
J J
JJ
Department of Biology, Boston University, Massachusetts 02215, USA.
Baum
M J
MJ
Tobet
S A
SA
D000818:Animals; D004622:Embryo, Mammalian; D005260:Female; D005289:Ferrets / Q000502:physiology*; D019004:Galanin / Q000096:biosynthesis*; D007032:Hypothalamus, Anterior / Q000166:cytology / Q000502:physiology*; D008297:Male; D009919:Orchiectomy; D010052:Ovariectomy; D011301:Preoptic Area / Q000166:cytology / Q000502:physiology*; D012016:Reference Values; D012727:Sex Characteristics
D019004:Galanin