AIM: to determine whether clonidine(Clo) ameliorate ischemia_induced disturbances of dopamine(DA), 5_hydroxytryptamine(5_HT),
norepinephrine(NE) and endothelin(ET) levels in rat′s forebrain. METHODS:Male Sprague_Dawley rats were anesthetized with 30 mg/kg pentobarbital sodium i.p.,Two subclavian arteries were ligated at its proximal end. Ischemia_induced forebrain damage was produced by two carotid ligation for 30 min and releasing carotid ligatures for 60 min. The levels of monoamines(NE, DA, 5_HT) were measured by flourospectrophotometry. ET determination was performed with radioimmunoassay. RESULTS: After 30 min′s ischemia followed by 60 min′s recirculation, NE and 5_HT levels in forebrain
significantly decreased by 42% and 24% respectively( P<0.01 ). However DA level significantly increased by about 33%. Meanwhile, ET levels in plasma and forebrain were significantly increased by about 95% and 156% respectively( P<0.01) . Compared with the ischemia group(Isc), Clo (100,or 200 μg/kg iv) significantly ameliorated NE and 5_HT levels disorder induced by ischemia_reperfusion damage. Elevated in ET levels in forebrain and plasma were also significantly decreased in clonidine_treated groups compared with those in the ischemia group. CONCLUSION: Clo reduced the ischemia_induced disorders in brain NE, 5_HT, and.ET levels, but this amelioration did not reach statistical significance in DA level.