Androgen-sensitive preganglionic neurons innervate the male rat pelvic ganglion

Abstract

In adult male rats many pelvic autonomic ganglion cells change in structure and function after androgen deprivation. In this study we have investigated whether preganglionic neurons in the lumbar and sacral spinal cord that innervate these ganglion cells are also androgen-sensitive. Numerous spinal neurons retrogradely labelled from the pelvic ganglion possessed androgen receptor immunoreactivity and this was diminished by castration or enhanced by additional testosterone exposure. These comprised 27–77% of all preganglionic neurons innervating the pelvic ganglion, depending on the spinal level and whether animals were administered testosterone prior to sacrifice or not. When adult animals were castrated, no change occurred in the soma size or number of primary dendrites in these lumbar or sacral preganglionic neurons. Mean dendrite length was also determined in lumbar preganglionic neurons supplying the pelvic ganglion, but was not affected by castration. However, the total volume of lumbar preganglionic terminal varicosities supplying each noradrenergic pelvic ganglion cell decreased in parallel with the volume of the target neuron. These studies show that many preganglionic autonomic neurons involved in pelvic reflexes are androgen-sensitive, but that androgens selectively influence particular neuronal compartments. The prevalence of androgen receptors in these neurons suggests that testosterone may directly influence gene expression of preganglionic neurons. Together these studies suggest that testosterone (or a metabolite) has widespread actions on pelvic reflex circuits during adulthood and that under conditions of diminished circulating androgens a variety of reflex activities may not function optimally.