Substance P-like immunoreactivity in cerebellar mossy fibers and terminals in the red-eared turtle, Chrysemys scripta elegans

Abstract

Using immunohistochemical methods, a population of mossy fibers and terminals with Substance P-like immunoreactivity has been observed in the cerebellum of the turtle, Chrysemys scripta elegans. The immunoreactive axons of mossy fibers can be traced into the granule cell layer of the cerebellum from a distinct bundle of axons with Substance P-like immunoreactivity in the tegmentum. Their terminals are most numerous in the rostrolateral part of the cerebellum. The mossy fiber terminals and their axons do not stain in control sections treated with antisera blocked with synthetic Substance P or in sections processed for enkephalin-like immunoreactivity. The cells of origin of the immunoreactive mossy fibers were not identified. The observations provide further evidence that cerebellar mossy fibers differ histochemically and that such differences may be related to their use of different transmitters or modulators. The observations also suggest that there are significant species-differences in the projections of neurons which contain Substance P.