Morehead State University

Poster Title

The Time-Dependent Effects of Amphetamine Administration on Feeding

Institution

Morehead State University

Abstract

Amphetamine (AMPH) produces a series of time-dependent effects on behaviors such as activity and feeding. Following a moderate dose of AMPH, animals display a transient period of excitation and reduced food intake followed by an acute withdrawal marked by a hypoactivity and hypophagia around hour 20 post-administration. The purpose of the present study was to further characterize the time-dependent effects of AMPH on feeding. Specifically, we were interested in demarcating the effects of administration time on AMPH-induced acute withdrawal. Rats were housed individually in chambers where their activity could be monitored 24 hrs a day. Feeding, under a fixed ratio 1 (FR1) schedule, was restricted to eight interspersed hours of the day. One group (N=8) received AMPH (2.0 mg/kg) at lights off and a separate group (n=8) received AMPH at lights on. Administering AMPH at lights on, just before the inactive period in the rat, more closely models the schedule of human drug-users who typically self-administer at night. Independent of administration time, AMPH produced a series of time-dependent effects on feeding that were consistent with those previously reported for activity. Rats displayed acute reduced intake, a period of acute withdrawal occurring around hour 20 post-administration, and recovery. Further research on AMPH-induced acute withdrawal is warranted in order to better understand the physiological and psychological factors that underlie the motivation to continue using drugs of abuse.

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The Time-Dependent Effects of Amphetamine Administration on Feeding

Amphetamine (AMPH) produces a series of time-dependent effects on behaviors such as activity and feeding. Following a moderate dose of AMPH, animals display a transient period of excitation and reduced food intake followed by an acute withdrawal marked by a hypoactivity and hypophagia around hour 20 post-administration. The purpose of the present study was to further characterize the time-dependent effects of AMPH on feeding. Specifically, we were interested in demarcating the effects of administration time on AMPH-induced acute withdrawal. Rats were housed individually in chambers where their activity could be monitored 24 hrs a day. Feeding, under a fixed ratio 1 (FR1) schedule, was restricted to eight interspersed hours of the day. One group (N=8) received AMPH (2.0 mg/kg) at lights off and a separate group (n=8) received AMPH at lights on. Administering AMPH at lights on, just before the inactive period in the rat, more closely models the schedule of human drug-users who typically self-administer at night. Independent of administration time, AMPH produced a series of time-dependent effects on feeding that were consistent with those previously reported for activity. Rats displayed acute reduced intake, a period of acute withdrawal occurring around hour 20 post-administration, and recovery. Further research on AMPH-induced acute withdrawal is warranted in order to better understand the physiological and psychological factors that underlie the motivation to continue using drugs of abuse.