Regional somatostatin distribution in the rat striatum

Somatostatin-like immunoreactivity (SLI) was detected by a specific radioimmunoassay in extracts from rat striatum. There was a topographic distribution of somatostatin with the highest levels in the nucleus accumbens and ventromedial striatum and the lowest levels in the dorsolateral striatum. This suggests that somatostatin-containing afferents to the striatum may originate from limbic system nuclei which project in a similar distribution. Gel permeation chromatography showed 5 distinct peaks of immunoreactive somatostatin. The two largest peaks coeluted with somatostatin 14 (SS-14) and somatostatin 28 (SS-28) and accounted for 72 and 12% of the total immunoreactivity, respectively. Reversed phase high pressure liquid chromatography confirmed that the majority of immunoreactive material co-chromatographs with SS-14; a smaller amount co-chromatographed with SS-28.