Akademik Veri Yönetim Sistemi
POLISH JOURNAL OF PHARMACOLOGY, cilt.51, sa.4, ss.301-309, 1999 (SCI-Expanded)
This study was designed to investigate the effects of preferential D-1 (SCH 23390) and D-2 (haloperidol) dopamine (DA) receptor antagonists and their interaction with low-dose (1 mg kg) D-amphetamine during the acquisition of two-way shuttle avoidance in rats. In the course of training, the dissociation of drug effects on response latencies was observed. Haloperidol (0.05 mg/kg) caused significant reduction in the frequency of short-latency avoidance responses that was only partially compensated by concomitant amphetamine administration. In contrast, SCH 2339 (0.025 mg/kg) did not affect the frequency of short-latency responses but lowered probability of avoidances emitted toward the end of 5 s interval between the onsets of conditoned and unconditioned stimuli (CS-UCS interval). Amphetamine compensated for this impairment by increasing frequency of short-latency avoidances well above the control level. These results argue for different nature of short- and long-latency avoidance responses, and suggest involvement of DA D-2 receptors in the process of response initiation facilitated by amphetamine. Interestingly, a profound behavioral breakdown was observed under higher dose of SCH 23390 (0.05 mg/kg), but only when applied together with amphetamine. The latter result seems to confirm the notion that behavioral output of dopaminergic transmission may depend more on the balance between D-1 and D-2 receptors than on the independent modulation of particular receptor system.