Neuroscience letters
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Neuroscience letters · Aug 2004
Antinociception induced by chronic exposure of rats to cigarette smoke.
To investigate if chronic exposure to cigarette smoke induces analgesia, rats were exposed to concentrated cigarette smoke in an environmental chamber over four successive 5-day blocks (6 h/day), with 2 smoke-free days between blocks. A control group was exposed to room air. Tail flick latencies increased significantly (analgesia) during each smoke exposure block, with a relative decline in analgesia across blocks (tolerance) and a return to control levels during the first three smoke-free interludes while remaining higher after the conclusion of the 4-week exposure period. ⋯ D.) ng/ml at the end of weekly smoke exposure and declined to 44.9 +/- 10.6 ng/ml 24 h after withdrawal. Rats lost weight during smoke exposure and quickly regained weight during smoke-free interludes and at the cessation of smoke exposure. Analgesia may contribute to the initiation of smoking, and rapid reversal of the analgesic effect following acute exposure may contribute to the difficulty in quitting smoking.
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Neuroscience letters · Aug 2004
Identification of adenosine A1 and A3 receptor subtypes in rat pial and intracerebral arteries.
The expression and microanatomical localization of adenosine A1 and A3 receptor subtypes were investigated in rat pial and intracerebral arteries by immunoblotting, immunohistochemistry and in situ hybridization techniques. Pial artery membranes develop immune bands of approximately 79 and 52 kDa when exposed to anti-A1 and anti-A3 receptor protein antibodies respectively. Sympathectomy performed by bilateral superior cervical ganglionectomy did not change the pattern of adenosine A1 or A3 receptor immunochemistry. ⋯ In situ hybridization histochemistry revealed a strong signal for A1 receptor and a moderate signal for A3 receptor in the tunica media of pial arteries, within smooth muscle. The present study indicates that rat pial and intracerebral arteries besides to the well characterized A2a and A2b receptors, express also A1 and A3 receptor subtypes. The identification of cerebrovascular A1 and A3 adenosine receptor subtypes may stimulate further research for detailing the mechanism(s) of regulation of cerebral circulation by adenosine.