EXPRESSION OF ESTROGEN-RECEPTOR IN THE FACIAL NUCLEUS IS SUPPRESSED BY ESTRADIOL, BUT NOT BY TESTOSTERONE, INDICATING A LACK OF REQUIREMENTFOR AROMATIZATION
C. Orikasa et al., EXPRESSION OF ESTROGEN-RECEPTOR IN THE FACIAL NUCLEUS IS SUPPRESSED BY ESTRADIOL, BUT NOT BY TESTOSTERONE, INDICATING A LACK OF REQUIREMENTFOR AROMATIZATION, Brain research, 693(1-2), 1995, pp. 112-117
The transient expression of estrogen receptor (ER) in the ventromedial
subnucleus of the facial nucleus was previously detected in the newbo
rn rat, and the expression of ER molecules was down-regulated by daily
injections of estradiol. Here we examined possible involvement of aro
matization in this process. ER molecules were measured by immunohistoc
hemistry and in situ hybridization histochemistry after daily injectio
ns of testosterone propionate (TP;100 mu g/0.02 ml) and estradiol benz
oate (EB; 10 mu g/0.02 ml) in the male pups castrated within 24 h of b
irth. Daily injections of TP for 5 consecutive days did not suppress E
R and ER mRNA in the facial nucleus, while they were both suppressed b
y daily injections of EB. Moreover, aromatase immunoreactivity was not
detected in the facial nucleus of both castrated, TP injected and int
act control males at 6 days of age. The present findings therefore sug
gest that ER molecules expressed transiently in the facial nucleus are
not directly involved in masculine sexual differentiation of the brai
n in newborn rat.