The dopamine receptor agonist 7-OH-DPAT modulates the acquisition and expression of morphine-induced place preference

The pattern of effects seen with 7-OH-DPAT suggests that it may be useful for treating opiate dependence and craving, although involvement of dopamine D2 receptors cannot be excluded.

Abstract

The present study investigated the effects of systemic administration of the putative dopamine D3 receptor agonist 7-hydroxy-N,N-di-n-propyl-2-aminotetralin (7-OH-DPAT) on the acquisition and expression of morphine-induced place preference in male Wistar rats. Using a a 3-day schedule of conditioning it was found that 7-OH-DPAT in a broad dose range (0.01, 0.25 and 5.0 mg/kg) did not produce significant place preference. However, the administration of either 0.25 or 5.0 mg/kg of 7-OH-DPAT 15 min prior to the exposure to morphine (1 mg/kg) prevented the acquisition of a morphine place preference, whereas the 0.01 mg/kg dose of the dopamine receptor agonist was uneffective. In addition, when 7-OH-DPAT was acutely administered 15 min prior to the testing session of an already established morphine place preference, the 0.01 mg/kg dose prevented the expression of this conditioned response. This effect was not observed with either 0.25 and 5.0 mg/kg doses of this dopamine D3 receptor agonist. It was suggested that the different dose related effects of 7-OH-DPAT on the acquisition and expression of morphine place preference might be related to the intrinsic ability of this agonist for interacting with pre- and postsynaptic dopamine D3 receptors located in limbic projecting areas of the mesencephalic dopamine system, although involvement of dopamine D2 receptors cannot be excluded. The pattern of effects seen with 7-OH-DPAT suggests that it may be useful for treating opiate dependence and craving.