Role of orexinergic system in the effects of morphine on food and water intake in male rat

 Introduction: Hypothalamic orexinergic neurons playan important role in food consumption and expresses µ-opioid receptor. This study was investigated the interaction of orexinergic system on effects of morphine on food and water intake in male rats. Materials and Methods: 40 male Wistar rats (250–300 g) were used in this study. The animals were operated stereotaxic and then after a week recovery period were divided into the following groups: 1. control 2.vehicle injection 3. morphine 4. orexin receptor 1 antagonist 5. orexin receptor 1 antagonist + morphine group. Drugs were injected into lateral ventricle (LV) after 12 hours food deprivation and then, the feeding and drinking behaviors were calculated 4h after injection.  Results: The injection of morphine into LV increased the amount of food intake and numbers of referral to feeding plate. Administration of orexin receptor1 antagonist (SB334867) attenuated significantly morphine-induced feeding, but had no effect on morphine induced water consumption. Morphine decreased water intake but increased numbers of referral for water bottle, which this effect was significantly attenuated by administration of SB334867. Conclusion: It may be orexin is at least one of the pathways of opiates effects on food and water intake.