Decreased neurocalcin immunoreactivity in sympathetic and parasympathetic neurons of the major pelvic ganglion in aged rats.

摘要

In the rat the majority of sympathetic and parasympathetic postganglionic neurons that innervate the pelvic viscera are located together in the major pelvic ganglia. We have ascertained that it is only the sympathetic population of this ganglion that exhibits age-associated attrition. Recent immunohistochemical investigations of the distribution of calcium binding proteins in this ganglion in young adult and aged rats have demonstrated that calbindin-D28k is only present in the sympathetic neurons and that the number of calbindin-immunoreactive sympathetic neurons of the aged ganglion was dramatically reduced. In the present study we have investigated the distribution of neurocalcin (NC) alpha isoform in the major pelvic ganglion. In young adults 98.7% of sympathetic neurons (identified by anti-tyrosine hydroxylase immunostaining) and 98% of parasympathetic neurons (identified by anti-nitric oxide synthase immunostaining) contained NC immunoreactivity and these figures are reduced to 68 and 45.5% in the aged group. Thus, unlike calbindin-D28k, NC is not confined to the sympathetic neuron population in the major pelvic ganglion and decreases significantly in old age in both neuronal populations. The likely effects are to impair intracellular calcium-dependent signalling in neurons of the major pelvic ganglion, possibly compounding the effects of the previously reported decrease in calbindin-D28k in the sympathetic population.