Central regulation of intraocular pressure and cardiovascular apparatus with clonidine in conscious rabbits

Effects of clonidine on intraocular pressure (IOP), arterial blood pressure (BP) and heart ratc (HR) were cvaluated in normotensive conscious rabbits. Ocular and arterial hypotension and sinus bradycardia induced by intracerebroventricular (icv third ventricle) clonidine (0.1-5 vg/rabbit) were reduced by icv yohimbine ( 1O vg/rabbit) , naloxone ( 4 vg/rabbit) , bicuculline (2.5 vg/rabbit), acetylsalicylic acid (100 Ug/rabbit) or flunoxaprofcn (100 vg/rabbit). Our results suggest that aradrenerg opiateic, peptidergic, GABAergic and prostaglandin systems are involved in ocular and cardiovascular effects induced by clonidine and that central nervous system is involved in the regulation of IOP.