EXPRESSION OF VASOPRESSIN MESSENGER-RNA IN EXTRAHYPOTHALAMIC NUCLEI OF THE HOMOZYGOUS BRATTLEBORO RAT IS NOT MODULATED BY TESTOSTERONE

Previous studies from this and other laboratories have shown that leve ls of vasopressin (VP) mRNA are reduced in both hypothalamic magnocell ular and extrahypothalamic nuclei of the homozygous Brattleboro rat (H OM) when compared to the normal Long-Evans (LE) and heterozygous Bratt leboro rats (HET). Since extrahypothalamic VP gene expression is depen dent on testosterone (T), we measured plasma T in HOM, HET and LE rats . The plasma T level of the intact HOM rat was not significantly diffe rent from intact LE or HET rats. Manipulation of circulating gonadal s teroids by castration and T replacement was found to regulate the expr ession of VP mRNA in the bed nucleus of the stria terminalis and media l amygdala of LE and HET rats, but does not appear to modify the absen ce of VP mRNA in neurons ill these nuclei in the HOM rat.