Possible involvement of nucleus accumbens D1-like dopamine receptors in the morphine-induced condition place preference in the offspring of morphine abstinent rats.

AIMS

Previous researches demonstrated that genetics and environment are two essential factors to prone individuals to drug abuse. Our previous data showed that dopaminergic system changed in the offspring of morphine-abstinent rats. In the present study, we evaluated whether blocking the D1-like dopamine receptors (DR) in the nucleus accumbens (NAC) affect the rewarding effect of morphine in the offspring of morphine-abstinent rats.

MAIN METHODS

In the study, male and female Wistar rats received morphine orally for 21 days. Ten days after last morphine administration, animals prepared to mate either with a morphine abstinent or a drug-naive rat. Adult male offspring were chosen for further evaluation. SCH23390 (0.01 μg/rat) was administrated intra-NAC during the conditioning phase in the CPP paradigm (morphine 7.5 mg/kg).

KEY FINDINGS

Obtained data showed that morphine administration (7.5 mg/kg) did not induce conditioning in the offspring of the morphine-abstinent parent(s) (p < 0.001) compared with the control group. However, when SCH23390 injected in the NAC during the induction phase, the offspring of morphine-abstinent rats were conditioned with the same dose of morphine.

SIGNIFICANCE

Previous studies showed that the offspring of morphine-abstinent rats are more prone to opioid consumption, and also developed tolerance to the rewarding effect of morphine. Current data indicated that blockade of D1-like DR in the NAC could prevent morphine-induced tolerance in these offspring. Therefore, inhibition of D1-like DR in the NAC might be a new candidate against morphine-reinforcing effect in the offspring of morphine-abstinent parent(s).