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 acti vation 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 techniq ues. Nicotinic activation was triggered for neurones of the major pelvic ga nglion by stimulating the hypogastric, pelvic and cavernous nerves and for coeliac neurones by stimulating the splanchnic nerves. Testosterone modifie d the resting membrane potential of neurones in the major pelvic ganglion b y triggering a slow depolarization, and was without significant effect on t he resting membrane potential of coeliac ganglion neurones. In neurones of the major pelvic and coeliac ganglia, testosterone had no significant effec t on the firing pattern, on the characteristics of the action potential (fi ring threshold, duration, overshoot) and on the after-hyperpolarization (am plitude and duration). Testosterone affected, in opposite ways, the nicotin ic activation of neurones of the two prevertebral ganglia. In the major pel vic ganglion, testosterone triggered an increase in the amplitude of excita tory postsynaptic potentials induced by stimulation or the hypogastric, pel vic and cavernous nerves with a single pulse, revealing a facilitation of n icotinic 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 funct ions, its facilitatory action being exerted on neurones df the major pelvic ganglion which is particularly involved in the control of the urogenital t ract. Our study reinforces the concept, derived from neuroanatomical and ph armacological studies, of the major pelvic ganglion as a major peripheral t arget for testosterone.