TACHYKININ NK3 RECEPTOR AGONIST BLOCKS SODIUM DEFICIENCY-INDUCED SHIFT IN TASTE REACTIVITY

Intracerebroventricular (i.c.v.) injections of tachykinin NK3 receptor agonists suppress NaCl intake by sodium deficient rats. The brief exp osure, taste reactivity test was used to examine the effect of tachyki nins on the immediate, oral reinforcing properties of NaCl (0.5 M) in sodium replete and sodium deficient male rats. In sodium replete rats, intraoral infusions of NaCl elicited a mixed response comprised of a similar number of ingestive and aversive responses following i.c.v. in jections of saline and succinyl-[Asp(6),N-Me-Phe(8)]substance P, (6-11 ), (SENK), a NK3 receptor agonist. When sodium deficient, saline injec ted rats showed a reliable increase in ingestive and a decrease in ave rsive taste reactivity responses. Lateral i.c.v. injections of SENK bl ocked the shift in taste reactivity responses by sodium deficient rats , indicating that concentrated NaCl retained its aversive taste proper ty.