Action of caffeine, L-PIA and their combination on memory retention in the rat

Rats were trained to run in a staircase and to stop on the 3rd, 6th, 9th and 12th steps. The increase of errors (arrest on any other step) after 2O days of interruption of the daily training was evaluated after a chronic administration (15 days) of L-PIA (N6-(L-phenylisopro-pyl)adenosine) 1 mg/kg/day; caffeine 15,45,8O mg/kg/day and of the combination of L-PIA 1 mg/kg/day with 15, 45 and 80 mg/kg/day of caffeine. In the controls and after caffeine administration, the interruption of the daily training caused a reduction of correct responses. After L-PIA alone or in combination with caffeine there was no reduction of correct responses after 2O days of no daily training. These results indicate that in the behavioral situation of our experiments there was no antagonism between caffeine and L-PIA.