Some parameters of conditioned immunosuppression: species difference and CS-US delay

Area of Science:

• Behavioral Neuroscience
• Immunology
• Psychopharmacology

Background:

• Conditioned immunosuppression is a phenomenon where immune responses can be classically conditioned.
• Previous research suggests a potential dissociation between taste aversion learning and conditioned immunosuppression.

Purpose of the Study:

• To investigate the relationship between taste aversion and conditioned immunosuppression.
• To determine if cyclophosphamide-induced immunosuppression can be classically conditioned to a saccharin taste cue.

Main Methods:

• Rats and mice were exposed to a saccharin solution (CS) followed by an immunosuppressant drug, cyclophosphamide (US).
• The plaque-forming-cell response was measured upon reexposure to the CS.
• Experiments varied animal models (rats, mice) and the delay between CS and US (up to 6 hours).

Main Results:

• Reexposure to the saccharin CS elicited a conditioned suppression of the plaque-forming-cell response in experimental groups.
• This effect was observed in both rats and mice.
• No delay gradient was found in either behavioral or immunologic data, even with a 6-hour CS-US delay.

Conclusions:

• The findings demonstrate robust conditioned immunosuppression.
• The parallel nature of taste aversion and conditioned immunosuppression suggests a lack of dissociation between these processes.
• This implies that learning mechanisms underlying taste aversion may also govern conditioned immunosuppression.