Oral sensation of ethanol in a primate model III:: responses in the lingual branch of the trigeminal nerve of Macaca mulatta

Ethanol administered orally has been shown to elicit a powerful response in rhesus monkey taste nerves. In this study we focused on the effects of ethanol on lingual non-gustatory receptors by recording from 70 single lingual nerve fibers. Of these 70 fibers, 54 (78%) responded to one or more concentrations of 0.7-12 M ethanol; 16 fibers (22%) were not affected. In 48 (69%) fibers, ethanol increased nerve activity, whereas 6 fibers (9%) exhibited suppression, which was displayed as a diminished response to mechanical stimulation. The excitatory response was characterized by regular impulse activity after a latency of 3-40 sec. With higher concentrations of ethanol, the latency became shorter, and the impulse activity evoked became higher. In many fibers the response peaked and ceased before the end of the 52-sec long-stimulation period. Most of the fibers affected by ethanol responded to light touch and cooling. During repeated touch, ethanol initially potentiated and then abolished the response to mechanical stimulation. Methanol and propanol gave similar results. Butanol only inhibited nerve activity. (C) 2002 Elsevier Science Inc. All rights reserved.