Shock-prod burying test in rats: autonomic and behavioral responses

Heart rate (HR), core temperature (CT) and gross locomotor activity (GLA) were recorded in rats by a computerized telemetry system before, during and after 15-min exposure to a constantly electrified (2mA) or nonelectrified (0mA) prod which was presented through a hole in the home cage with woodshavings on the floor [shock-prod burying (SPB) test]. Measurement of both autonomic and behavioral response continued up to 60 min after introduction of the prod in the home cage. Twenty-four h after the SPB test, rats were tested for retention. During the SPB test, significant increases in HR, respective to baseline values, were observed in both the 2mA and 0mA group, but the tachycardiac response in the former group significantly outweighed that in the latter group. In shocked rats, HR remained elevated during the entire 45-min posttest period, whereas HR declined immediately after removal of the prod in nonshocked animals. An onset in rise in CT was observed in the 2mA, but not in the 0mA group, during prod exposure time, which eventually resulted in an additional-more than two-fold--increase after termination of the test and outlasted total recording time. Marked behavioral activation was observed in the 2mA group, whereas the 0mA responded to a lesser extent. Approach and exploration of the prod was reduced when the prod was electrified. The total time spent by rats burying the prod was significantly longer in the shocked than in the nonshocked group. When exposed to the nonelectrified prod after 24 h, total burying time was reduced in the 2mA group but still significantly longer than in the 0mA group.(ABSTRACT TRUNCATED AT 250 WORDS)