Effects of lesions of a sexually dimorphic nucleus in the preoptic/anterior hypothalamic area on the expression of androgen- and estrogen-dependent sexual behaviors in male ferrets.
The male nucleus of the preoptic/anterior hypothalamic area (MN-POA/AH) is a sexually dimorphic structure present in male, but not in female ferrets. Ovariectomized female ferrets given increasing dosages of estradiol benzoate (EB) normally run faster towards a stud male in an L-maze (i.e. become more proceptive). In two separate experiments, only gonadectomized males with bilateral damage to the MN-POA/AH following large or small electrolytic lesions approached stud males more quickly in response to EB. By contrast, males which received sham lesions, unilateral large POA/AH lesions, or bilateral lesions which missed the MN-POA/AH on at least one side failed to show EB-induced reductions in approach latencies in pre- or post-operative tests. Males with large POA/AH lesions also displayed significant post-operative decrements in masculine sexual behaviors during treatment with a high dose of testosterone propionate (TP). Less severe, but statistically significant deficits in masculine coital performance were also observed in males with small lesions which damaged the MN-POA/AH bilaterally; however, the ability of these males to achieve intromissions appeared normal. Together, these results suggest that the MN-POA/AH of the male ferret exerts an inhibitory influence on estrogen-dependent proceptive responsiveness, but play only a minor role in the control of masculine coital behavior.
Cherry
J A
JA
Department of Biology, Boston University, MA 02215.
Baum
M J
MJ
D000818:Animals; D007025:Anterior Hypothalamic Nucleus / Q000502:physiology; D004958:Estradiol / Q000502:physiology*; D005260:Female; D005289:Ferrets / Q000502:physiology*; D007031:Hypothalamus / Q000502:physiology*; D008297:Male; D010053:Ovary / Q000502:physiology; D011301:Preoptic Area / Q000502:physiology; D012727:Sex Characteristics; D012726:Sexual Behavior, Animal / Q000502:physiology*; D013737:Testis / Q000502:physiology; D013739:Testosterone / Q000502:physiology*
D013739:Testosterone; D004958:Estradiol