Effect of adenosine A2A receptor antagonists on motor disorders induced by 6-hydroxydopamine in rat

PURPOSE: To investigate the role of adenosine A2A receptors on 6-OHDA-induced motor disorder in rat. METHODS: In order to induce experimental model of Parkinson's disease, 6-hydoxydopamine (8 μg/rat) was injected unilaterally into the SNc. After three weeks as a recovery period, 6-OHDA-induced bradykinesia and balance disturbances were assessed by using beam traversal test 10, 30 and 60 minutes after intraperitoneal injections of the drugs (caffeine, SCH58261). RESULTS: The results showed that 6-OHDA (8 μg/rat, Intra-SNc) induced motor disorders of Parkinson's disease and increased elapsed time in the beam test (p<0.001). Injection of caffeine (30 mg/kg, i.p.) and SCH58261 (2 mg/kg, i.p.) attenuated elapsed time on beam (p<0.01 and p<0.001). We showed that acute administration of caffeine and SCH 58261 can improve the 6-OHDA-induced bradykinesia and motor disturbance. CONCLUSION: Adenosine A2AR antagonists improve 6-OHDA-motor deficit and this effect seems to be mediated by the inhibition of A2A presynaptic receptors in substantia nigra pars compacta.

Effect of alpha-7 nicotinic acetylcholine receptor activation on beta-amyloid induced recognition memory impairment. Possible role of neurovascular function

PURPOSE: To evaluate the effects of PHA-543613 (α7-nAChR agonist) and galantamine (acetylcholinesterase inhibitor (AChEI)) on recognition memory and neurovascular coupling (NVC) response in beta-amyloid (Aβ) 25-35-treated mice. METHODS: PHA-543613 (1 mg/kg, i.p.), and galantamine (3 mg/kg, s.c.), effects were tested in Aβ25-35 mice model of AD. α7-nAChR antagonist, methyllycaconitine (MLA) (1 mg/kg, i.p.), was used for evaluation of receptor blockade effects. Recognition memory in animals was assessed by the novel object recognition (NOR) task. NVC response was analyzed by laser-doppler flow meter in barrel cortex by whisker stimulation method. RESULTS: Both, PHA-543613 and galantamine improve recognition memory in Aβ-treated animals. However, the advantageous effects of PHA-543613 were significantly higher than galantamine. Also, pretreatment with MLA reversed both galantamine and PHA-543613 effects on NOR. Impaired NVC response in AD animals was improved by PHA-543613 and galantamine. However, MLA pretreatment disrupts this function. CONCLUSION: Activation of α7-nAChR improved recognition memory possible through enhancement of neurovascular response in Alzheimer's disease in animals.