Effects of testosterone on the electrical properties and nicotinic transmission of the major pelvic and coeliac ganglion neurones.

The effects of testosterone on the electrical properties and nicotinic activation of prevertebral ganglion neurones were investigated in vitro on the male rat major pelvic ganglion and rabbit coeliac ganglion. The electrical activity of the neurones was recorded using intracellular recording techniques. Nicotinic activation was triggered for neurones of the major pelvic ganglion by stimulating the hypogastric, pelvic and cavernous nerves and for coeliac neurones by stimulating the splanchnic nerves. Testosterone modified the resting membrane potential of neurones in the major pelvic ganglion by triggering a slow depolarization, and was without significant effect on the resting membrane potential of coeliac ganglion neurones. In neurones of the major pelvic and coeliac ganglia, testosterone had no significant effect on the firing pattern, on the characteristics of the action potential (firing threshold, duration, overshoot) and on the after-hyperpolarization (amplitude and duration). Testosterone affected, in opposite ways, the nicotinic activation of neurones of the two prevertebral ganglia. In the major pelvic ganglion, testosterone triggered an increase in the amplitude of excitatory postsynaptic potentials induced by stimulation of the hypogastric, pelvic and cavernous nerves with a single pulse, revealing a facilitation of nicotinic activation. On coeliac ganglion neurones, testosterone elicited a decrease in the amplitude of excitatory postsynaptic potentials induced by stimulation of the splanchnic nerves, indicating an inhibition of nicotinic activation. Our study shows that testosterone acts differently on neurones of prevertebral ganglia involved in the nervous control of different functions, its facilitatory action being exerted on neurones of the major pelvic ganglion which is particularly involved in the control of the urogenital tract. Our study reinforces the concept, derived from neuroanatomical and pharmacological studies, of the major pelvic ganglion as a major peripheral target for testosterone.