Comparison of progressive-ratio performance maintained by cocaine, methylphenidate and secobarbital

Area of Science:

• Pharmacology
• Behavioral Neuroscience

Background:

• Understanding drug reinforcement is crucial for addiction research.
• Progressive-ratio schedules assess the motivation to obtain drugs.

Purpose of the Study:

• To compare the reinforcing efficacy of cocaine, methylphenidate, and secobarbital in baboons.
• To investigate dose-response effects on drug-seeking behavior.

Main Methods:

• Baboons were trained on a progressive-ratio schedule for intravenous drug self-administration.
• Ratio requirements increased weekly until response rates fell below a criterion.
• Breaking points were determined for each drug and dose.

Main Results:

• Cocaine yielded higher breaking points than methylphenidate at an equivalent dose (0.4 mg/kg).
• Dose manipulation of cocaine and methylphenidate had minimal impact on breaking points.
• Increasing secobarbital doses (6.0 and 12.0 mg/kg) led to significantly higher breaking points.

Conclusions:

• Cocaine and methylphenidate exhibit comparable reinforcing effects under these conditions.
• Secobarbital demonstrates greater reinforcing efficacy than the stimulants at the tested doses.
• These findings contribute to understanding the differential motivation for various drug classes.