Dendritic branching in cortical pyramidal cells in response to ovariectomy in adult female rats: suppression by neonatal exposure to testosterone.

Female Long-Evans rats were treated with oil or testosterone propionate (TP) at birth (postnatal day zero, PN0) and PN1. As adults, animals from each group were ovariectomized or sham operated. Four months later the brains were prepared using a modified Golgi-Cox staining procedure. In neonatally oil-treated females, ovariectomy in adulthood increased the dendritic arbor of layer II/III pyramidal neurons of the parietal cortex; in addition, there were modest increases in apical dendritic spine density. The dendritic arbor of the pyramidal neurons of intact neonatally TP-treated females was greater than that of intact oil-treated females, but in these animals there was no increase in dendritic arbor in response to ovariectomy.