Optical imaging of the spontaneous neuronal activities in the male rat major pelvic ganglion following denervation of the pelvic nerve.

Measurement of groups of neuronal activities following pelvic nerve transection to the major pelvic ganglion (MPG) of the rat was performed using voltage-sensitive dye (RH795) and an optical recording system. In control MPG, averaged neuron diameters were 32.0 +/- 0.6 x 22.6 +/- 0.4 microm. Application of KCl (10-50 mM) to the ganglia exhibited excitation which increased in a dose-dependent fashion. Fluctuating membrane potentials were not observed in control ganglion neurons. After the denervation of pelvic nerve chronically (2-6 weeks), the spontaneous neuronal activities were recorded in 91% of the experiments (n = 32). The activity was occurring somewhat periodically (2-15 s). Averaged neuron diameters were 41.3 +/- 1.3 x 24.7 +/- 0.9 microm in denervated MPG which is significantly larger than control. Since average neuron size increased 4 weeks after the denervation, the new excitatory activities could have influenced the change of the neuron size. The new activities might produce contraction of target organs in the pelvic viscera.