جستجوی مقالات مرتبط با کلیدواژه « GABAB receptor » در نشریات گروه « پزشکی »

Many mechanisms are involved in pain transmission in the spinal cord. Therefore, combination of drugs acting on different kinds of mechanisms might be useful for analgesia. We investigated the interaction betweenγ-aminobutyric acid （GABA）B receptor agonist, baclofen, and N-methyl-D-aspartate （NMDA） receptor antagonist, AP-5, orα-amino-3-hydroxy-5-methylisoxazole-4-propionic acid （AMPA） receptor antagonist, YM-872, on analgesic effects in acute thermal and formalin induced pain models of rats.

Male Sprague-Dawley rats implanted with lumbar intrathecal catheters were given intrathecal baclofen, AP-5, YM872 or combination of baclofen and AP-5 or YM872, then tail flick test or formalin test was performed. Fifty % effective doses of combinations were obtained and isobolographic analysis was done.

The combination of baclofen and AP-5 or YM872 showed dose dependent increases in tail flick latency and decreases in flinching response in the formalin test. In the tail flick test, ED50s of the combination of baclofen + AP-5 or YM872 were close to the additive points. In both phases of the formalin test, ED50s of the combination of baclofen + AP-5 or YM872 were significantly lower than additive points.

For acute thermal pain, both AP-5 and YM872 had similar additive analgesic effects with baclofen. For chemical induced acute pain, both AP-5 and YM872 had similar synergistic analgesic effects with baclofen, but for facilitated pain, YM872 had stronger synergistic analgesic effects with baclofen than AP-5.

Hypertension is considered an independent risk factor for cardiovascular mortality in diabetic patients. The present study was designed to determine the role of gamma amino butyric acid B (GABAB) receptor and L-arginine (L-Arg) in GABA-induced vasorelaxation in normal and streptozotocin-induced diabetic rat vessels. Diabetes was induced by a single i.p. injection of streptozotocin (STZ, 60 mg/kg). Eight weeks later, superior mesenteric arteries of all groups were isolated and perfused according to the McGregor method. Baseline perfusion pressure of STZ diabetic rats was significantly higher than non-diabetic rats in both intact and denuded endothelium. In the presence of faclofen, a selective GABAB receptor blocker, GABA-induced relaxation in intact and denuded endothelium mesenteric beds of STZ diabetic rats was suppressed, but this response in non-diabetic rats was not suppressed. Our results showed that in the presence of L-Arg, a nitric oxide precursor, GABA induced vasorelaxation in both diabetic and non-diabetic vessels. From the results of this study, it may be concluded that the vasorelaxatory effect of GABA in diabetic vessel is mediated by the GABAB receptor and nitric oxide, but it seems that in non-diabetic vessel GABAB receptor does not play any role in GABA-induced vasorelaxation, but nitric oxide induced GABA relaxation in non-diabetic vessel.