Central nervous system and peripheral mechanisms in ocular hypotensive effect of cannabinoids
J. H. Liu and A. C. Dacus
Systemic administration of cannabinoids decreases intraocular pressure
(IOP). To determine whether the mechanism of action originates in the
central nervous system, we administered various cannabinoids into the
cerebral ventricles of conscious New Zealand albino rabbits. When delta
9-tetrahydrocannabinol (delta 9-THC), delta 8-tetrahydrocannabinol,
cannabinol, and cannabidiol were given intravenously, only delta 9-THC
produced dose-dependent ocular hypotension and miosis. Bolus administration
into the cerebral ventricles or ventriculocisternal perfusion of delta
9-THC did not change IOP or pupil size. In urethane-anesthetized rabbits,
IOP and blood pressure were lowered by intravenous administration of delta
9-THC but not by bolus cerebral administration. These observations indicate
that the action of cannabinoids on IOP does not originate in the central
nervous system. Alteration of blood pressure may be involved in the
mechanism of ocular hypotension induced by delta 9-THC.
