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 exposure, taste reactivity test was used to examine the effect of tachykinins 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. injections of saline and succinyl-[Asp6,N-Me-Phe8]substance P, (6-11), (SENK), a NK3 receptor agonist. When sodium deficient, saline injected rats showed a reliable increase in ingestive and a decrease in aversive taste reactivity responses. Lateral i.c.v. injections of SENK blocked the shift in taste reactivity responses by sodium deficient rats, indicating that concentrated NaCl retained its aversive taste property.