Contraction of Urinary Bladder by Central Norepinephrine Originating in the Locus Coeruleus

Abstract Studies were performed to elucidate the role of the locus coeruleus, which is rich in norepinephrine-containing cell bodies, in vesical function using a-chloralose anesthetized cats. Stimulation of the locus coeruleus caused contraction of the urinary bladder, which was not affected by transection of the bilateral hypogastric nerves, but blocked by intravenous administration of hexamethonium, a ganglion blocking agent. In animals with transected hypogastric nerves, the locus coeruleus-induced contraction was inhibited by intrathecal administration of phentolamine (α-blocker) and prazosin (α1-blocker), but not affected by intrathecal sotalol (β-blocker) or yohimbine (α2-blocker). In animals treated with reserpine, the locus coeruleus-induced contraction was enhanced by intravenous application of L-dopa, a precursor of norepinephrine. These results suggest that norepinephrine derived from the locus coeruleus activated preganglionic neurons in the sacral intermediolateral nuclei via ad-receptors, thereby producing urinary bladder contraction.