抄録
It is suggested that the GABAergic system in the ventral pallidum (VP) plays a role in taste palatability. Taste palatability shift occurs as a function of conditioned taste aversion (CTA). To elucidate the role of VP GABAergic system on CTA, we examined the effects of microinjections of a GABAA receptor antagonist, bicuculline, on the retrieval of CTA memory. We measured consumption of conditioned stimulus (CS) using one-bottle test (Experiment 1) and observed the ingestive or aversive behavior to CS using taste reactivity test (Experiment 2). Rats received 5 mM saccharin or 0.3 mM quinine hydrochloride as CS, immediately followed by an i.p. injection of 0.15 M lithium chloride (20 ml/kg). After this conditioning, vehicle or bicuculline (12.5–200 ng) was bilaterally infused into the VP immediately before re-exposure to the CS. In Experiment 1, the bicuculline microinjections significantly increased the intake of the saccharin CS, but not the QHCl CS. In Experiment 2, while the control rats infused with vehicle showed a variety of aversive responses (e.g. gaping, chin rubbing, head shaking, forelimb flails), the rats infused bicuculline failed to show these aversive responses. These results indicate that the blockade of GABAA receptors in the VP attenuates aversion to saccharin CS, and this may be due to elimination of aversive responses. Thus, it is suggested that the GABAergic system in the VP plays a critical role in the expression of CTA. [J Physiol Sci. 2006;56 Suppl:S97]
