Morehead State University

Poster Title

Short-Term and Long-Term Effects of Psychostimulants on Social Behavior and Spontaneous Locomotion

Institution

Morehead State University

Abstract

Behavioral excitation is an acute effect of psychostimulants, such as methamphetamine (METH) and 3,4 methylenedioxy-methamphetamine (MDMA or ‘ecstasy’). Phencyclidine (PCP) also produces similar excitation. These drugs, however, work on different neurotransmitter systems: PCP via the glutamatergic system, MDMA via the serotonergic system, and METH via the dopaminergic and serotonergic systems. The present study examined acute and long-term effects of these drugs on social interaction and locomotion in rats. METH, MDMA, or PCP was administered twice a day at 12 hour intervals for 2 consecutive days. Rats were placed in open-field arenas and locomotor activity and social initiation was measured for a 60 min period to examine the acute (immediately after 1st and 3rd injection) and long-term (3, 7, and 14 days after 3rd injection) drug effects on behavior. During the acute state, MDMA and METH produced a distinctive pattern in adult rats: MDMA injections produced hyperactivity, whereas only the first METH injection produced hyperactivity. Neither METH nor MDMA produced long-term effects on locomotion. In contrast, acute METH and PCP treatments abolished social interaction in juvenile rats, and this drug-induced decrease in social interaction continued throughout the 14 day withdrawal interval. In light of evidence that METH, MDMA, and PCP produce neurological damage, the long-lasting decrease in social interaction observed after METH and PCP treatments may reflect drug-induced changes in brain. Further, these findings suggest that locomotor activity may not be a sensitive measure of the long-term effects of these drugs.

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Short-Term and Long-Term Effects of Psychostimulants on Social Behavior and Spontaneous Locomotion

Behavioral excitation is an acute effect of psychostimulants, such as methamphetamine (METH) and 3,4 methylenedioxy-methamphetamine (MDMA or ‘ecstasy’). Phencyclidine (PCP) also produces similar excitation. These drugs, however, work on different neurotransmitter systems: PCP via the glutamatergic system, MDMA via the serotonergic system, and METH via the dopaminergic and serotonergic systems. The present study examined acute and long-term effects of these drugs on social interaction and locomotion in rats. METH, MDMA, or PCP was administered twice a day at 12 hour intervals for 2 consecutive days. Rats were placed in open-field arenas and locomotor activity and social initiation was measured for a 60 min period to examine the acute (immediately after 1st and 3rd injection) and long-term (3, 7, and 14 days after 3rd injection) drug effects on behavior. During the acute state, MDMA and METH produced a distinctive pattern in adult rats: MDMA injections produced hyperactivity, whereas only the first METH injection produced hyperactivity. Neither METH nor MDMA produced long-term effects on locomotion. In contrast, acute METH and PCP treatments abolished social interaction in juvenile rats, and this drug-induced decrease in social interaction continued throughout the 14 day withdrawal interval. In light of evidence that METH, MDMA, and PCP produce neurological damage, the long-lasting decrease in social interaction observed after METH and PCP treatments may reflect drug-induced changes in brain. Further, these findings suggest that locomotor activity may not be a sensitive measure of the long-term effects of these drugs.