@article {10.3844/ajptsp.2010.119.124, article_type = {journal}, title = {The Intracerebroventricular Administration of W-7, A Calmodulin Inhibitor, Attenuate the Development of Morphine Tolerance in Rats}, author = {Sepehri, Gholamreza and Sheibani, Vahid and Azarang, Afrooz and Shamsizadeh, Ali and Afarinesh, Mohammad Reza and Azizollahi, Saeed and Sepehri, Ehsan}, volume = {5}, year = {2010}, month = {Jun}, pages = {119-124}, doi = {10.3844/ajptsp.2010.119.124}, url = {https://thescipub.com/abstract/ajptsp.2010.119.124}, abstract = {Problem statement: The present study was performed to determine the effect of Intracerebroventricular (ICV) administration of W-7, a specific calmodulin inhibitor, on the analgesic effect and development of tolerance to antinociceptive effect of acute and chronic morphine administration respectively. Approach: This study was carried out on male wistar rats, weighing 200-250 g. For acute experimental protocol, Morphine was injected intraperitonealy in a single dose (5 mg kg-1). For chronic experimental protocol, Morphine was administered daily (15 mg kg-1 for 8 days). The threshold to thermal nociceptive stimuli was measured by tail-flick test. In acute and chronic experiments, W-7 (0.25, 0.5 and 1 μmol/rat) was injected through ICV at different paradigms. Maximal Possible Effect percentage (MPE%) was considered as analgesia index. Results: Our result showed that W-7 (0.25, 0.5 and 1 μmol/rat) injections before acute morphine administration significantly reduced the analgesic effect of morphine compared with morphine treated group (all p}, journal = {American Journal of Pharmacology and Toxicology}, publisher = {Science Publications} }