en بررسی اثر آدنوزین و کافیین بر فعالیت خودبه خودی نورون های هسته پاراژیگانتوسلولاریس در موش های صحرایی وابسته به مرفین Nervous system (others) Others Experimental research article Experimental research article <span style="FONT-SIZE: 12pt FONT-FAMILY: "Palatino Linotype" mso-fareast-font-family: 'Times New Roman' mso-bidi-font-family: 'Times New Roman' mso-ansi-language: EN-US mso-fareast-language: EN-US mso-bidi-language: AR-SA">In this study the effect of adenosine and caffeine on spontaneous activity of paragigantocellularis (PGi) neurons was investigated. The spontaneous activity of PGi neurons was significantly decreased by microinjection of adenosine (10 nM, 0.5 µl) into PGi nucleus of both control and morphine-dependent rats. The decrease in firing rate of PGi neurons of morphine-dependent rats was greater than that of control. There was also significant enhancement of spontaneous activity of PGi neurons 8-15 min after caffeine administration (50 mg/kg i.p.) in both control and morphine-dependent rats. However, the effect of caffeine in morphine-dependent rats was higher than that of control. These data suggest that there is an increase in the sensitivity to chemicals, which interact with adenosine receptors in morphine- dependent rats. Nevertheless, considering a common second messenger system (cAMP) for adenosine (A₁) and opioid (µ) receptor, it is proposed that up-regulation and hypersensitivity of A₁ adenosine receptors are responsible for these results in morphine-dependent rats.</span> Morphine; Tolerance; Dependence; Nucleus paragigantocellularis; Single unit recording; Adenosine receptors; Caffeine 29 38 http://ppj.phypha.ir/browse.php?a_code=A-10-110-116&slc_lang=en&sid=1 Mohsen Khalili 3200319475328460011623 3200319475328460011623 Yes Dept. Physiology, school of Medicine, Shahed University, Tehran, Iran Saeed Semnanian 3200319475328460011624 3200319475328460011624 No Yaghoub Fathollahi 3200319475328460011625 3200319475328460011625 No