Glossopharyngeal nerve transection reduces quinine avoidance in rats not given presurgical stimulus exposure

Behavioral studies on the effects of bilateral glossopharyngeal nerve (GL) transection on quinine responsiveness have yielded mixed results. These dif ferences may be explained by the presence or absence of presurgical exposur e with the tastant. In the present experiment we measured unconditioned lic king to quinine in rats that had no exposure to quinine before surgery. Rat s were water deprived and trained to lick water during 10 s trials in an au tomated gustometer. Next, they were divided into groups that received eithe r GL transection or sham surgery (CON). Following recovery, the water-depri ved rats were presented with seven concentrations of quinine hydrochloride (0.003-3 mM) and distilled water. The number of licks to each tastant was a veraged over three days of testing. Rats with GL transection licked signifi cantly more to the higher concentrations of quinine relative to CON rats, r esulting in a 0.44 log(10) unit shift in the quinine concentration-response curve. These results when considered with prior work suggest that experien ce before nerve transection may have a small protective effect on taste-gui ded behavioral responsiveness to quinine in rats. (C) 1999 Elsevier Science Inc.