Evidence for the involvement of 5-HT1A receptors in the mediation of exploratory locomotor activity in the rat.

The 5-HT(1A) receptor agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT), 0.1 mg/kg(-1) subcutaneously, produced a suppression of horizontal ('locomotion') and vertical ('rearing') activity, in an open field arena. This effect was partially antagonized by treatment with (-)pindolol, 2 mg/kg(-1) subcutaneously. (-)Pindolol by itself produced a small, but statistically significant suppression of locomotor activity. There were no effects on rearing activity by (-)pindolol. In comparison with saline-treated controls, 8-OH-DPAT increased peripheral, relative to total, horizontal activity in the open field arena. (-)Pindolol adminis tration restored this pattern of activity to normal levels in 8-OH-DPAT-treated animals, without altering the relation peripheral to total activity by itself.