Release of somatostatin from extra-hypothalamic rat brain slices: inhibition by dopamine and morphine.

Calcium-dependent potassium-evoked release of somatostatin-like immuno-reactivity (SSLI) and preloaded [3H]noradrenaline ([3H]NA) could be demonstrated simultaneously from slices of rat cerebral cortex, globus pallidus and trigeminal nucleus. The release of [3H]NA from cortical slices differed from that of somatostatin (SS) in its K+-dependency, with the release of SS having a higher threshold. Both morphine (10 microM) and dopamine (50 microM) significantly inhibited the potassium-evoked release of SS from the cerebral cortex, without affecting its basal release. The effect of morphine was naloxone reversible.