Abstract # 1822 Behaviorally conditioned immunosuppression: Effects of a prolonged post-conditioning retention interval

Abstract

In our established model of behaviorally conditioned immunosuppression in rats, a novel taste (saccharin) as conditioned stimulus (CS) is paired with the immunosuppressive drug cyclosporine A (CsA) as unconditioned stimulus (US). By re-presenting the CS during retrieval, rats avoid drinking the saccharin (conditioned taste aversion; CTA) and concomitantly display immunosuppression reflected by a reduction in splenic T-cell IL-2 production. However, for a possible application of this specific learning protocol in clinical conditions, it is essential to know whether the strength of the conditioned immunosuppression is restricted to a specific time interval that elapses between acquisition and retrieval (retention interval). Thus, the present pilot study analyzed the effects of a delayed testing after behavioral conditioning by comparing retrieval after a commonly used short (2 days) with long (7 and 14 days) retention intervals. Our preliminary results show that retrieval after seven days slightly decelerated extinction of the conditioned response on the behavioral level (CTA) compared to retrieval after two days. Retrieval after 14 days led to the extinction of the conditioned response already on the second day of CS re-exposure. We are still analyzing possible conditioned suppression of peripheral immune functioning assessed after the different retention intervals (anti-CD3 stimulated IL-2 and IFN- γ cytokine production). However, further and additional studies need to be conducted to clarify in more detail, whether prolonged retention intervals may influence retrieval of behaviorally conditioned immunosuppression.