ABSTRACT
AIM To investigate the effect of clonidine on intraocular pressure(IOP) and the possible role in which ? adrenergic mechanism plays. METHODS The change on IOP was observed following clonidine administered via three different routes: (1)clonidine topically administered to eyes; (2)clonidine intracerebroventricularly injected (icv)or topically administered after yohimbine or prazosin icv; (3)microinjection of clonidine into locus coeruleus(LC). RESULTS Clonidine decreased IOP significantly, ? 2 adrenoceptor antagonist, but not ? 1 adrenoceptor antagonist, can reverse the decreasing effect on IOP caused by clonidine icv and administered topically. CONCLUSION Clonidine administered both topically or intracranially can decrease IOP;? 2 adrenoceptor in central nervous system is involved in this effect.