ZAHEDI KHORASANI M, HAJIZADEH S, SEMNANIAN S, FATHOLLAID Y. CEREBRAL BLOOD FLOW REGULATION IN ANESTHETIZED MORPHINE DEPENDENT RATS: THE ROLE OF THE ADENOSINE SYSTEM. Med J Islam Repub Iran 2005; 18 (4) :353-359
URL:
http://mjiri.iums.ac.ir/article-1-619-en.html
theDept. Of Physiology, School of Medical Sciences, Tarbiat Modarres University, P.O. Box I4115-11I, Tehran, Iran , Hajizads@modares.ac.ir
Abstract: (4372 Views)
Adenosine has many of the characteristics of a regulator of cerebral blood flow
and adenosine receptors change in morphine dependency. In this study the changes in
adenosine receptors' responsiveness of pial vessels in the hind limb area of the sensory
cortex were evaluated in morphine dependent rats (MDR) using the laser Doppler
flowmetry technique. Adult male Sprague Dawley rats (250-350 g) 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 MD R, so that the
increase of rCBF inMD R is statistically significant (p<0.01 ). This response was inhibited
by theophylline (5x 10-5M). Lidocaine (2%) reduced adenosine-induced increase
in rCBF o f MDR. N6-cyclohexyladenosine (10-6, 10-5, 10-4 M) and 8 -
cyclopentyltheophylline (1 G-6M) as a selective agonist and antagonist of adenosine A l
receptors had no significant effect on rCBF in control and MDR. CGS-21680 (10-6
M) as a selective adenosine A2a receptor agonist, increased rCBF in MDR significantly
(p<0.05). This response was antagonized by ZM-241385. NECA (10-6M) as
a adenosine A2b receptor agonist, 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