Serotonin-immunoreactivity in the cerebellum of two neurological mutant mice and the corresponding wild-type genetic stocks.

Using a serotonin (5-HT)-specific antibody, we examined the 5-HTergic innervation of the cerebellum in the normal mouse (+/+) and in two neurological mutants: weaver (wv/wv), which are characterized by a genetically determined loss of granule cells, and 'Purkinje cell degeneration' (pcd/pcd), which are characterized by a genetically determined loss of Purkinje cells. In normal cerebellum, serotonin-immunoreactive (5-HT-ir) fibers are discrete and ascend to all three layers of the cerebellar cortex. Serotonin-immunoreactive fibers have a much higher density in the atrophic cerebella of both weaver and pcd mutants, where they form multidirectional contours. These anatomical findings provide a profile of 5-HT axon innervation of mouse cerebellum and extend previous neurochemical observations on the metabolic state of cerebellar 5-HT in neurological mutants.