The involvement of interoceptive factors in the maintenance of heroin-seeking behavior.

The role of interoceptive stimuli in conditioned heroin-seeking behavior was investigated using forty-two naive male Wistar rats. A 21-day Phase I period in which 28 animals self-injected heroin in saline solution was followed by a 5-day Phase II period in which 7 animals were allowed access to the original solution; 7 animals were allowed access to saline only; 7 animals were allowed access to distilled water; and 7 animals were allowed no access to any solution. Results showed that only the heroin and (heroin-associated) saline groups shows a significant difference in operant rate compared to animals that had been continually exposed to saline only. It was concluded that heroin-seeking behavior was maintained in the (heroin-associated) saline group as a result of physiological conditioning following repeated association of saline with heroin.