Somatostatin selectively inhibits noradrenaline release from hypothalamic neurones

Abstract

Somatostatin is a hypothalamic peptide hormone which inhibits growth hormone release from the anterior pituitary1. However, biochemical and morphologica¹ investigations have revealed that Somatostatin is located not only in the hypothalamus but also in other brain areas (for example the cerebral cortex) where it occurs and in nerve cell bodies and fibres^2–5 from which it can be released in a Ca²⁺-dependent manner⁶. It has therefore been suggested that the neuropeptide may have functions in the central nervous system other than its effect on growth hormone release⁷; one possible action is that of a neuromodulator^4,6. Therefore, hypothalamic and cerebral cortical slices of the rat were used to examine whether Somatostatin modules the electrically or CaCl₂-evoked release of tritiated monoamines from monoaminergic neurones. It is reported here that Somatostatin inhibits ³H-noradrenaline release from the hypothalamus (but not from the cerebral cortex) but does not affect the release of ³H-dopamine and ³H-serotonin.