IMMUNOHISTOCHEMICAL LOCALIZATION OF THE SOMATOSTATIN SST2(A) RECEPTORIN THE RAT-BRAIN AND SPINAL-CORD

The neuropeptide somatostatin is widely distributed in the CNS and is believed to play a role as a neurotransmitter or a neuromodulator. Som atostatin mediates its actions by the binding of the peptide to high a ffinity membrane receptors. The genes for five somatostatin receptor t ypes have been cloned recently and Northern blotting and in situ hybri dization studies have shown that the transcripts of all five types are expressed in the CNS. Here we report the cellular distribution of som atostatin sst(2(a)) receptor protein in the adult rat CNS, using a pol yclonal anti-peptide antibody directed against a portion of the C-term inal domain of the receptor. The specificity of the affinity-purified antibody was demonstrated by Western blotting and immunolabelling of c ells transfected with a hemagglutinin epitope-tagged version of the ss t(2(a)) receptor. Immunohistochemistry showed a distinct distribution of the receptor protein in the rat brain. Cells and processes were lab elled in a number of areas, including the basolateral amygdala, the lo cus coeruleus, the endopiriform nucleus, the deep layers of the cerebr al cortex, the subiculum, the claustrum, the habenula, the interpendun cular nucleus, the hippocampus and the central grey. In the spinal cor d, the substantia gelatinosa showed strongly-labelled cell bodies and their processes. This study provides an improved understanding of the distribution of the sst(2(a)) receptor in rat brain. Copyright (C) 199 6 IBRO.