Photomicrographs showing expression of ER-[beta] in the AVPV in a representative control and Aroclor 1221-treated rat are shown in Figure 2A and B.
In comparing results of the SON with those in the AVPV, although the volumes of the SON and AVPV were comparable (Figure 4, A vs.
Aroclor 1221 caused a substantial down-regulation of numbers of ER-[beta]-positive cells in the AVPV, a key brain area controlling reproductive function (Simerly 1998; Wiegand et al.
The AVPV of female rats is essential for the regulation of hypothalamic gonadotropin-releasing hormone neurons and the control of the estrogen-induced surge of gonadotropin-releasing hormone and luteinizing hormone (Gu and Simerly 1997.
Our results are consistent with a masculinizing effect of Aroclor 1221 on this cell phenotype, similar to effects of exogenous estrogen, which also decreased ER-[beta] cell number in the AVPV of neonatal female rats (Orikasa et al.