Changes in schedule-controlled response and schedule-induced drinking after cholinergic blockers in rats

Area of Science:

• Neuroscience
• Pharmacology
• Behavioral Science

Background:

• Cholinergic systems play a crucial role in regulating behavior.
• Distinguishing between central and peripheral cholinergic effects is vital for understanding drug actions.

Purpose of the Study:

• To investigate the differential effects of tertiary and quaternary cholinergic blockers on operant responding and adjunctive drinking in rats.
• To determine if central versus peripheral cholinergic blockade has distinct behavioral outcomes.

Main Methods:

• Rats were trained on a fixed interval (FI) 1.5 min schedule of food reinforcement.
• Rats received administrations of tertiary (atropine sulfate, scopolamine hydrobromide) and quaternary (atropine methylnitrate, scopolamine butylbromide) cholinergic blockers.
• Operant response (lever-pressing) and adjunctive drinking behaviors were measured.

Main Results:

• Tertiary blockers, especially scopolamine, increased total responses and altered response patterns.
• Quaternary blockers did not significantly affect total responses or response patterns.
• Atropine sulfate, atropine methylnitrate, and scopolamine suppressed adjunctive drinking, but scopolamine butylbromide did not.
• Central blockers (atropine sulfate, scopolamine) decreased the index of curvature for drinking rates, suggesting altered drinking patterns.

Conclusions:

• Central cholinergic blockade enhances operant responding and suppresses adjunctive drinking.
• Peripheral cholinergic blockade primarily suppresses adjunctive drinking.
• Central cholinergic blockade induces notable changes in response and drinking patterns during an FI schedule.