| RESEARCH ARTICLE
|Year : 2014 | Volume
| Issue : 1 | Page : 57-62
Nitric oxide in central amygdala potentiates expression of conditioned withdrawal induced by morphine
Manizheh Karami1, Mahnaz Rahimpour2, Sara Karimi2, Hedayat Sahraei3
1 Neurophysiology Research Center; Department of Biology, Faculty of Basic Sciences, Shahed University, Tehran, Iran
2 Department of Biology, Faculty of Basic Sciences, Shahed University, Tehran, Iran
3 Department of Physiology, Baghiyatallah University of Medical Sciences, Tehran, Iran
Objective: The aim of this study was to evaluate if nitric oxide (NO) in the central amygdala (CeA) is involved in the expression of withdrawal aspects induced by morphine.
Materials and Methods: Male Wistar rats (weighing 200-250 g) were bilaterally cannulated in the CeA and conditioned to morphine using an unbiased paradigm. Morphine (2.5-10 mg/kg) was subcutaneously injected once a day throughout the conditioning phase of the procedure. This phase also included 3-saline paired sessions. Naloxone (0.1-0.4 mg/kg, intraperitoneally [i.p.]), an antagonist of opioid receptors, was administered i.p. 10 min prior to testing of morphine-induced withdrawal features. The NO precursor, L-arginine (0.3-3 μg/rat) was intra-CeA injected prior to testing of naloxone response. To evaluate the involvement of NO system an inhibitor of NO synthase (NOS), N G -nitro-L-arginine methyl ester (L-NAME) (0.3-3 μg/rat), was injected ahead of L-arginine. Control group received saline solely instead of drug. As a complementary study, the activation of NOS was studied by nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d).
Results: Morphine induced a significant increase in wet dog shaking and grooming behaviors compared with controls. Injection of naloxone pre-testing of morphine response significantly reversed the response to morphine. However, pre-microinjection of L-arginine intra-CeA recovered the response to morphine. Injection of L-NAME intra-CeA ahead of L-arginine though had no effect behaviorally, but, inhibited the NOS which has been evidenced by NADPH-d.
Conclusion: The present study shows that NO in the CeA potentiates the expression of conditioned withdrawal induced by morphine paired with naloxone.
Neurophysiology Research Center; Department of Biology, Faculty of Basic Sciences, Shahed University, Tehran
Source of Support: None, Conflict of Interest: None
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