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Sequential changes in behavior induced by continuous infusions of amphetamine in rats.
Psychopharmacology
|January 1, 1987
Summary
Continuous amphetamine infusion in rats alters behavior and dopamine levels. Initially, rats show oral stereotypies, later replaced by increased locomotion and reduced startle responses, linked to dopamine changes.
Area of Science:
- Neuroscience
- Pharmacology
- Animal Behavior
Background:
- Amphetamine is a stimulant known to affect behavior and neurotransmitter systems.
- Previous research indicates amphetamine's impact on dopamine levels and motor activity.
Purpose of the Study:
- To investigate the behavioral and neurochemical effects of continuous amphetamine infusion in rats.
- To characterize the temporal sequence of behavioral changes induced by sustained amphetamine exposure.
Main Methods:
- Rats received continuous amphetamine infusion (0.65 mg/kg/h) via Alzet minipumps for 5 or 9 days.
- Behavioral changes were monitored daily using behavioral pattern monitors (BPM).
- Dopamine levels in the corpus striatum and nucleus accumbens were measured.
Main Results:
- Amphetamine infusion induced a multiphasic behavioral response, starting with oral stereotypies and progressing to locomotor and investigatory activation.
- A reduction in tactile startle responses was observed after 9 days of infusion.
- Striatal dopamine levels decreased significantly by day 3, while nucleus accumbens dopamine showed a transient increase.
Conclusions:
- Continuous amphetamine infusion leads to a selective depletion of striatal dopamine.
- This dopamine depletion correlates with a shift from amphetamine-induced stereotypy to increased locomotor activity.
- The findings highlight the complex, time-dependent effects of amphetamine on behavior and dopamine pathways.