A10 SOMATODENDRITIC DOPAMINE AUTORECEPTOR SENSITIVITY FOLLOWING WITHDRAWAL FROM REPEATED COCAINE TREATMENT

The mesoaccumbens dopamine (DA) pathway is known to be involved in both the rewarding properties of cocaine and in behavioral sensitization to its locomotor-stimulating effects. We investigated changes in DA neurons in this pathway following withdrawal from repeated cocaine treatment. Rats were injected with 10 mg/kg cocaine or 1 ml/kg saline twice daily for 14 days. One day, 4 days and 8 days after treatment, inhibition of cell firing by the DA agonist apomorphine was measured in DA neurons using in vivo single cell recording techniques. As previously reported, the somatodendritic autoreceptor appeared subsensitive one day after treatment. This autoreceptor subsensitivity persisted four days, but not eight days, after treatment. Although not a persistent alteration, autoreceptor subsensitivity may be necessary to trigger other permanent changes involved in behavioral sensitization. © 1990.