Differential distribution of alternatively spliced somatostatin receptor 2 isoforms (sst2A and sst2B) in rat spinal cord.

We have recently shown that the cytoplasmic tail of the somatostatin receptor sst2 undergoes alternative splicing giving rise to two isoforms, SSt2A and sst2B. In the present study, we have raised polyclonal antibodies that specifically detect either sst2A or sst2B and used these antisera for immunocytochemical localization of the receptor proteins in the rat spinal cord. sst2A-immunoreactivity formed a dense network consisting of neuronal perikarya and dendrites in the superficial layers of the dorsal horn. In contrast, prominent sst2B-immunoreactivity was found on neuronal perikarya and proximal dendrites throughout the gray matter of the spinal cord. Taken together, we show that alternative carboxy-terminal splicing is involved in cell-specific expression of somatostatin receptor sst2 isoforms in rat spinal cord, and that sst2A and sst2B mediate effects of somatostatin at different cellular sites.