Role of dopamine--D2 receptor in spatial memory retention and retrieval determined using Hebb-Williams complex maze.

Effects of bromocriptine and sulpiride were observed on encoding and retrieval of spatial memory in Wistar rats using Hebb-Williams complex maze. Rat was placed in entry chamber and allowed to reach reward chamber. Ten trials were given each day per rat for 3 consecutive days. Within-day encoding score indicative of learning and between-day retrieval score indicative of memory were calculated. Effects of bromocriptine and sulpiride were observed on encoding and retrieval of spatial memory. General learning index was calculated to compare the effect on spatial memory between groups. Bromocriptine increased while sulpiride decreased within-day encoding index but had no effect on retrieval index. In general learning index, sulpiride group showed more errors whereas bromocriptine group did not show any difference as compared to control. These results suggest that dopamine D2 receptors are involved in memory encoding but not retrieval. Also general learning is under positive modulation by D2 receptors.