CEREBELLAR NITRIC-OXIDE SYNTHASE IS EXPRESSED WITHIN GRANULE CELL PATCHES INNERVATED BY SPECIFIC MOSSY FIBER TERMINALS - A DEVELOPMENTAL PROFILE

The nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) s taining technique was utilized as a marker of nitric oxide synthase (N OS) to map NOS expression in developing and adult rat cerebellum. NADP H-d-positive cells were first visualized in the cerebellar cortex at p ostnatal day 5 (PND5) which increased to peak levels by PND30 when the y began to exhibit a patch-like organization, In order to determine th e relationship of the NADPH-d staining pattern with messy fiber innerv ation, messy fiber projections were traced using cholera toxin B subun it or biocytin injected into the lateral reticular nuclei (LRtN) or po ntine nuclei (PtN), respectively, Double staining revealed that the cl ustered messy fiber terminals projecting from the ventrorostral LRtN a nd caudal PtN were well matched with NADPH-d-stained patches, This pat ch-like localization of NOS matched with specific messy fiber terminal s in adult cerebellum implicates these NOS patches as defining distinc t anatomical zones.