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Evaluation of the effect of piperine on the expression of morphine-induced conditioned place preference in male mice: Possible role of dopamine receptors
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Ali Rezaei   , Ghader Najafi *  , Saeid Abbasi Maleki |
| 1. Department of Pathobiology, Faculty of Veterinary Medicine, Ur.C., Islamic Azad University, Urmia, Iran |
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Abstract: (7 Views) |
Background: Piperine, the main alkaloid of black pepper, increases brain dopamine release. Given the importance of dopaminergic pathways in opioid-induced reward behaviors, this study aimed to investigate the effect of piperine on the expression of morphine-induced conditioned place preference (CPP) and the role of dopamine D1 and D2 receptors.
Methods: Male NMRI mice were evaluated in a 6-day protocol consisting of pre-conditioning, conditioning, and post-conditioning phases. After determining the effective dose of morphine in inducing CPP, the effects of piperine (10, 20, and 40 mg/kg) alone and in combination with morphine were assessed. Locomotor activity and exploratory behavior of the animals were also recorded in the open field test (OFT). To evaluate the dopaminergic mechanism, morphine-conditioned mice received a D1 receptor antagonist (SCH-23390; 0.05 mg/kg) or a D2 receptor antagonist (sulpiride; 5 mg/kg) 60 minutes prior to the administration of piperine (40 mg/kg).
Results: Morphine at doses of 5 and 10 mg/kg significantly induced CPP (p < 0.001; an increase of 1049.6% and 1140.8%, respectively). Piperine alone did not induce CPP or aversion (CPA) and did not cause locomotor changes in the OFT (p > 0.05). However, piperine (40 mg/kg) significantly potentiated the expression of morphine CPP by 51.6% (p < 0.001). Pretreatment with SCH-23390 and sulpiride significantly inhibited the potentiating effect of piperine
(p < 0.001; a decrease of 154.7% and 142.3%, respectively).
Conclusion: Piperine administration alone did not induce significant CPP or CPA. However, acute piperine administration may enhance morphine-induced CPP. This effect is likely mediated, at least in part, through the involvement of dopaminergic pathways.
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| Keywords: Conditioned Place Preference, Dopaminergic, Mice, Morphine, Piperine |
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Full-Text [PDF 1500 kb]
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Type of Study: Original Research |
Subject:
Neuroscience
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