Immunocytochemical study of catecholaminergic innervation in the guinea pig cochlea.

The enzymes for synthesis of catecholamine, tyrosine hydroxylase (TH), dopamine beta-hydroxylase (DBH), and phenylethanolamine N-methyl transferase (PNMT), have been immunocytochemically localized in the guinea pig cochlea. Two groups of catecholamine-containing neurons could be distinguished. The first group, which was TH-positive/DBH, PNMT-negative, was found in the inner spiral bundle and the tunnel spiral bundle. The other group was TH, DBH-positive/PNMT-negative, and was found around the blood vessels. The immunocytochemical evidence obtained in this experiment suggests that the catecholamines should play a functional role in the guinea pig cochlea.