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).
Keywords: CPP; D1 dopamine receptor; Morphine; Nucleus accumbens; Offspring.
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