REGIONAL DISTRIBUTION OF PROSTAGLANDIN-H SYNTHASE-2 AND NEURONAL NITRIC-OXIDE SYNTHASE IN PIGLET BRAIN

Immunohistochemical techniques were used to examine the distribution o f prostaglandin H synthase (PGHS)-2 and neuronal nitric oxide synthase (nNOS) in piglet brain. Samples from parietal cortex, hippocampus, an d cerebellum were immersion fixed in 10% formalin, sectioned at 50 mu m, and immunostained using specific antibodies against PGHS-2 and nNOS . Immunoreactivity for PGHS-2 was extensive throughout the areas exami ned. For example, PGHS-2 immunoreactive cells were present in all laye rs of the cortex, but were particularly dense among neurons in layers II/III, V, and VI. In addition, glial cells associated with microvesse ls in white matter showed PGHS-2 immunoreactivity. In contrast, nNOS i mmunoreactive neurons were Limited in number and widely dispersed acro ss all layers of the cortex and thus did not form a definable pattern. In the hippocampus, heavy PGHS-2 immunoreactivity was present in neur ons and glial cells in the subgranular region, stratum radiatum, adjac ent to the hippocampal sulcus, and in CA1 and CA3 pyramidal cells. Imm unostaining for nNOS displayed a different pattern from PGHS-2 in the hippocampus, and was mainly localized to the granule cell layer of the dentate gyrus and the mossy fiber layer. In the cerebellum, PGHS-2 im munoreactivity was heavily represented in the Bergmann glia and to a l esser extent in cells of the granular layer, whereas nNOS was detected only in Basket cells. There are four conclusions from this study. Fir st, PGHS-2 immunoreactivity is widely represented in the cerebral cort ex, hippocampus, and cerebellum of neonatal pigs. Second, glia cells a s well as neurons can show immunoreactivity for PGHS-2. And third, the distribution of nNOS is different from PGHS-2 immunoreactivity in the cerebral cortex, hippocampus, and cerebellum.