Sweet and Salty Taste Responses in Alcohol‐preferring (P) and Alcohol‐Nonpreferring (NP) Rats

Abstract

Naïve P rats showed increased mRNA and protein expression of T1R3 (a sweet taste receptor component) and TRPV1t (a putative benzamil (Bz)-insensitive salt taste receptor) in the anterior tongue and small intestine mucosal cells relative to NP rats. We investigated if up-regulation of receptors alter neural and behavior responses to sweet and salty stimuli in P rats. P rats showed a greater preference for 5% ethanol and 10% sucrose and greater chorda tympani (CT) taste nerve responses to sucrose, SC45647 and NaCl+Bz. Benzamil decreased NaCl preference in NP rats but not in P rats. A TRPV1t agonist, Maillard reacted peptides conjugated with galacturonic acid (GalA-MRPs), decreased preference for NaCl+Bz in P but not in NP rats. In P rats the concentration-CT response relation for ethanol and 0.5 M sucrose was higher and shifted to the left relative to NP rats. In naïve P rats and in NP rats chronically given 5% ethanol in a no choice paradigm, the concentration-CT response relation for TRPV1t agonists (resiniferatoxin and GalA-MRPs) and NaCl+Bz was enhanced and shifted to the left relative to naïve NP rats, but was unchanged in P rats. In NP rats, TRPV1t activity was increased by forced alcohol consumption to levels comparable to those of P rats. We conclude that chronic alcohol ingestion alters sweet and salt taste responses and may affect chemoreception in the gastrointestinal tract as well. Supported by DC-000122 and DC-005981.