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Paper IPM / Cognitive / 7458 |
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In the present study, the effects of intra-basolateral amygdala (BLA) injection of GABAA receptor agonist and antagonist on morphine-induced conditioned place preference (CPP) in male wistar rats have been investigated. Subcutaneous (s.c.) administration of different doses of morphine sulphate (1-9 mg/kg) produced a dose-dependent CPP. Using a 3-day schedule of conditioning, it was found that the GABAA receptor agonist, muscimol (0.125, 0.25 and 0.5 �g/rat) or the GABAA receptor antagonist, bicuculline (0.125, 0.25 and 0.5 mg/rat) did not produce a significant place preference or place aversion. Intra-BLA administration of muscimol (0.25 and 0.5 �g/rat) decreased the acquisition of CPP induced by morphine (6 mg/kg). On the other hand, intra-BLA injection of bicuculline (0.25 and 0.5 mg/rat) in combination with an ineffective dose of morphine (1 mg/kg) elicited a significant CPP. The response of different doses of muscimol was attenuated by bicuculline (0.125 and 0.25 �g/rat). Furthermore, intra-BLA administration of bicuculline but not muscimol before testing significantly decreased the expression of morphine (6 mg/kg)-induced place preference. The administration of the higher doses of bicuculline (0.25 and 0.5 mg/rat) during acquisition and the higher dose of muscimol (2 mg/rat) on the test day decreased the locomotor activity of the animals on the testing phase. It can be concluded that GABAA receptors in the amygdala are involved in morphine reward.
Theme: Neural basis of behavior
Topic: Drugs of abuse: opioids and others
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