Somatostatin--paracrine and neuromodulator peptide in gut and nervous system.

Somatostatin, a tetradecapeptide widely distributed in nervous tissue and gut, has inhibitory effects on secretion and neuromuscular activity. The actions of this peptide probably embrace three types of transmitter-receptor interaction, namely that of a neurotransmitter in the nervous system, that of a hormone in the hypophyseal portal circulation and that of a local (paracrine) effector in gut and pancreas.