Journal of neuroscience research
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The effect of graded doses of systemically injected sodium pentobarbital on several classes of spinal neurons was studied using spinal cats. Classes of spinal neurons included unidentified dorsal horn cells, ascending tract dorsal horn cells, and motoneurons. Single unit activity of spinal neurons was evoked by electrically stimulating a peripheral nerve with an intensity strong enough to excite both A and C fibers. ⋯ The reflex activity of motoneurons elicited by stimulation of peripheral nerve was much more sensitive to pentobarbital than that of dorsal horn cells. In general, activity evoked by peripheral unmyelinated fibers was more susceptible to pentobarbital than was that evoked by myelinated fibers. However, intravenous injections of pentobarbital produced nondifferential suppression of dorsal horn cell activity evoked by noxious and innocuous mechanical stimuli applied to the peripheral receptive fields.
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The ultrastructure, afferent input, and sites of termination of neurons containing neuropeptide Y-like immunoreactivity (NPY-LI) were examined in the adult rat nucleus accumbens by using the peroxidase-antiperoxidase (PAP) method. The NPY-LI was seen in sparsely distributed, spindle-shaped perikarya having cross-sectional diameters of 15-20 microns. These perikarya exhibited highly invaginated nuclear membranes and thin rims of cytoplasm containing Golgi lamellae, dense-core vesicles, and other organelles. ⋯ The GAD-labeled terminals formed symmetric junctions primarily with the more numerous unlabeled dendrites. However, a few synaptic junctions also were detected between the GAD-labeled terminals and dendrites showing immunogold labeling for NPY. We conclude (1) that in the rat nucleus accumbens, NPY-LI is found principally in neurons of the aspiny type and (2) that the output from these presumably intrinsic neurons to other neighboring neurons or blood vessels is at least partially modulated by GABA.