Modulatory Role of Oxytocin during Opioidergic Regulation of Food Intake in Rats


  • Kavita Gulati Department of Pharmacology, Vallabhbhai Patel Chest Institute University of Delhi, Delhi – 110007
  • Tarun Thakur Department of Pharmacology, Vallabhbhai Patel Chest Institute, University of Delhi, Delhi – 110007
  • Nishant Rai
  • K K Sharma Department of Pharmacology, University College of Medical Sciences, University of Delhi, Delhi – 110095. ** Presently Professor of Pharmacology, School of Medical Sciences & Research and Dean, School of Allied Health Sciences, Sharda University, Greater Noida – 201306 (UP).


Morphine, oxytocin, ketocyclazocine, food intake.


Effects of acute and chronic administration of μ- and k-opioid receptor agonists, morphine (MOR) and ketocyclazocine (KCZ), on food intake and their interaction with neuro-hypophysial neuropeptide, oxytocin (OXY) have been investigated in rats. After single administration of MOR (1 μg/rat,icv) food intake was increased during the light phase (0- 6 h) as well as dark phase (6-24 h) in naïve rats. Similarly, single administration of KCZ enhanced the food intake during the light phase but with not much change in food intake during the dark phase. However, after chronic administration the responses were differentially modified, i.e. there was a further enhancement of hyperphagic effect of MOR during light phase (0-6 h), whereas tolerance developed toorexiceffect of KCZ. Further, during dark phase, hyperphagic response was observed in response to both MOR and KCZ. During interaction studies with OXY, it was observed that pretreatment with OXY (0.1 μg/rat,icv) attenuated the hyperphagic response to single administration of both MOR and KCZ. OXY, per se, did not significantly affect the food intake response during light or dark phases of the diurnal cycle. However, on chronic treatment OXY (a) blocked the accentuation of hyperphagic response to MOR during both 0-6 h and 6-24h and(b) blocked the hyperphagic response to KCZ during 6-24 h. Results are discussed in the light of complex opioid-oxytocin interaction during food intake in rats.


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