كليدواژه :
آدنوزين , وابستگي به مورفين , جريان خون مغزي , cerebral blood flow , Morphine Dependent Rat , adenosine
چكيده لاتين :
Adenosine has many charachteristics which regulate cerebral blood flow and their receptors change in morphine dependency. In this study the changes in adenosine receptors responsiveness of pial vessels in hind limb area of sensory cortex were evaluated in morphine dependent rats (MDR) using the laser Doppler flowmetry technique. Adult male Sprague Dawley rats (250-350g) were used in all experiments. Animals were made morphine dependent, thereafter local effects of adenosine receptor agonists and antagonists on regional cerebral blood flow (rCBF) were investigated. Results obtained in this study show that adenosine (10^-5,10^-4,10^-3M) increases rCBF in a dose dependent manner in sham operated, control, and MDR, and the increase of rCBF in MDR is statistically significant (P<0.01). This response was inhibited by theophylline (5*10^-5M). Lidocaine (2%) reduced adenosine - induced increase in rCBF of MDR. N6-cyclohexyladenosine (10^-6, 10^-5, 10^-4M) and 8-cyclopentyltheophylline (10^-6M) selective agonist and antagonist of adenosine Al receptors, had no significant effect on rCBF in control and MDR. CGS-21680 (10-"M) an selective adenosine A2a receptor agonist, increased rCBF in MDR significantly (P<0.05). This response was antagonized by ZM-241385. NECA (10-6M) as an adenosine A2b receptor agoinst, increased rCBF in MDR significantly (P<0.05). This response was antagonized by Alloxazine. The results of this study indicate an increase in adenosine A2 receptors (including A2a and A2b subtypes) responsiveness in hind limb sensory cortex of MDR.
