Neural androgen receptor overexpression affects cell number in the spinal nucleus of the bulbocavernosus

Abstract

The spinal nucleus of the bulbocavernosus (SNB) is a sexually dimorphic neuromuscular system in which masculinization of cell number is thought to depend on perinatal androgen action in non-neural targets, but masculinization of cell size is thought to depend primarily on adult androgen action on SNB cells themselves. In order to test these hypotheses, we characterized the SNB of Cre/loxP transgenic mice that overexpress androgen receptor (AR) throughout the body (CMV-AR) or in neural tissue only (Nestin-AR). We additionally examined the effects of androgen manipulation in male mutants and wild type controls. We reproduced the expected sex differences in both motoneuron number and size, and the expected adult androgen dependence of SNB size. We found effects of genotype such that both Nestin-AR and CMV-AR have more SNB motoneurons than wildtype littermates, and that CMV-AR females have larger SNB motoneurons than Nes-AR or wild type females. These results raise the possibility that AR can act in neurons and/or glia to rescue SNB motoneurons, and on non-neural AR to increase SNB cell size.

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