Morehead State University

Poster Title

Dopamine D2 Receptor Activation and Acute Withdrawal

Institution

Morehead State University

Abstract

Administration of amphetamine (2.0 mg/kg sc) appears to produce an acute withdrawal state around hour 20 post-treatment in rats. One behavioral indicator of this state is hypo-activity. The purpose of the study was to see if the selective dopamine D2 receptor agonist quinpirole also produces hypo-activity around hour 20 post-treatment. Thirty-two male Wistar rats were individually housed in cubicles (40cm x 20 cm) in a 12-12 hour light-dark cycle and with free access to food and water. Images from a camera mounted above each cubicle were used to quantify activity in terms of total distance moved per hour. Animals were divided into four treatment groups, with eight animals in each group. Rats were first given at least two control treatments (rubbing of the nape of the neck or subcutaneous saline administration) followed by at least two experimental treatments (in different groups, saline, 0.2 mg/kg quinpirole, 0.4 mg/kg quinpirole, or 2.0 mg/kg amphetamine). Treatments were given at the start of the light period and were separated by at least a 48-hour interval. Patterns of activity following drug treatments were compared to patterns following control manipulations. Selective stimulation of the D2 receptor subtype with quinpirole produced a general suppression of activity through approximately hour 20 post-administration, but it did not appear sufficient to produce the hypo-activity around hour 20 indicative of acute withdrawal. Activation of the D2 receptor subtype does not appear sufficient to produce symptoms of withdrawal.

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Dopamine D2 Receptor Activation and Acute Withdrawal

Administration of amphetamine (2.0 mg/kg sc) appears to produce an acute withdrawal state around hour 20 post-treatment in rats. One behavioral indicator of this state is hypo-activity. The purpose of the study was to see if the selective dopamine D2 receptor agonist quinpirole also produces hypo-activity around hour 20 post-treatment. Thirty-two male Wistar rats were individually housed in cubicles (40cm x 20 cm) in a 12-12 hour light-dark cycle and with free access to food and water. Images from a camera mounted above each cubicle were used to quantify activity in terms of total distance moved per hour. Animals were divided into four treatment groups, with eight animals in each group. Rats were first given at least two control treatments (rubbing of the nape of the neck or subcutaneous saline administration) followed by at least two experimental treatments (in different groups, saline, 0.2 mg/kg quinpirole, 0.4 mg/kg quinpirole, or 2.0 mg/kg amphetamine). Treatments were given at the start of the light period and were separated by at least a 48-hour interval. Patterns of activity following drug treatments were compared to patterns following control manipulations. Selective stimulation of the D2 receptor subtype with quinpirole produced a general suppression of activity through approximately hour 20 post-administration, but it did not appear sufficient to produce the hypo-activity around hour 20 indicative of acute withdrawal. Activation of the D2 receptor subtype does not appear sufficient to produce symptoms of withdrawal.