The role of conditioned taste aversion in the hypophagia induced by intraperitoneal epinephrine and glucose.

It has been repeatedly shown that relatively high doses of epinephrine (E) and glucose (G) injected intraperitoneally (ip) produce hypophagia in fasted rats. In the present work we used a conditioned taste aversion (CTA) paradigm in order to test whether this effect could be due to "malaise." We determined the effect on food intake and saccharin preference with the following treatments: (a) E ip 100 and 250 micrograms/kg; (b) E ip 250 micrograms/kg with or without previous alpha 1 plus beta adrenergic blockade; (c) G ip 3.5 and 4 g/kg. Both doses of E significantly reduced food intake more than 75% but only the high dose produced a significant (50%) reduction in saccharin preference. Blockade of alpha 1 and beta adrenergic receptors completely suppressed the E-induced hypophagia but attenuated only slightly the taste aversivon effect. Both doses of G decreased food intake but only the high dose reduced saccharin preference; part of these effects would appear to be due to the high osmolarity of the solution. The present results indicate that E and G may induce CTA in our experimental conditions. However, their hypophagic and aversive effects seem to be elicited by different mechanisms.