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 transec tion to the major pelvic ganglion (MPG) of the rat was performed using volt age-sensitive dye (RH795) and an optical recording system. In control MPG, averaged neuron diameters were 32.0 +/- 0.6 x 22.6 +/- 0.4 mu m. Applicatio n of KCI (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 chronic ally (2-6 weeks), the spontaneous neuronal activities were recorded in 91% of the experiments (n = 32). The activity was occurring somewhat periodical ly (2-15 s). Averaged neuron diameters were 41.3 +/- 1.3 x 24.7 +/- 0.9 mu m in denervated MPG which is significantly larger than control. Since avera ge neuron size increased 4 weeks after the denervation, the new excitatory activities could have influenced the change of the neuron size. The new act ivities might produce contraction of target organs in the pelvic viscera. ( C) 1998 Elsevier Science Ireland Ltd. Ail rights reserved.