Intrathecal somatostatin modulates spinal sensory and reflex mechanisms: behavioral and electrophysiological studies in the rat.

Using behavioral and electrophysiological techniques, evidence was obtained that somatostatin (SOM) has an excitatory role in spinal sensory and reflex mechanisms of the rat. Intrathecal (i.t.) SOM (1 and 10 micrograms) induced a dose-dependent caudally directed scratching behavior lasting about 20 min. In decerebrated, spinalized, unanesthetized rats, small doses of i.t. SOM (10 ng-1 micrograms) increased the excitability of the hamstring flexion reflex. Similar effects on the reflex may be seen after conditioning afferent C-fiber activation. The results indicate that during C-afferent activity SOM may be released and may increase spinal cord excitability.