A Physiological and Pharmacological Study about the Use of α2 Agonist in the Control of Induced-Pain in Rats

Abstract

Dexmedetomidine (DEX) is the most recent agent of Alpha 2- adrenoceptor (α2- AR) agonists approved by FDA in 1999 for analgesia and sedation in the intensive care unit .it decrease sympathetic tone and attenuate the stress responses to anesthesia and surgery and produce antinociceptive effect in humans. The present study was designed to investigate the underlying mechanism of the effects of cold stress on neuropathic pain model i.e. chronic constriction injury (CCI) model of sciatic nerve in rats in comparison with dexmedetomidine (Dex ), an alpha 2 agonist. Male albino rats were divided into six groups (n = 8 for each group) as follows;  1st group of animals was exposed to repeated cold stress (RCS) at 4 °C (RCS group),  2nd group was kept without any temperature shifts (temperature was kept at 22± 1 °C) and served as a control unstressed (Sham RCS group),  3rd group had been exposed to chronic constriction injury (CCI) of the sciatic nerve (CCI group)  4th group was exposed to an identical dissection in the left paw, except that the sciatic nerve was not ligated (Sham CCI group),  5th group, single i.p. dose of dexmedtomidine hydrochloride (5 μg/kg).