The influence of delta 9-tetrahydrocannabinol on intraocular pressure in the anaesthetized cat.

delta 9-Tetrahydrocannabinol (delta 9-THC) was injected both intravenously and into the brain stem via the left vertebral artery. Contrary to results obtained with clonidine, neither the fall in intraocular pressure (IOP), nor the arterial hypotension induced by delta 9-THC, were enhanced after the 'central' administration of the drug. For clonidine, a central mechanism underlying the ocular hypotensive effect has recently been proposed. This suggestion is based upon the enhanced fall in IOP after 'central' administration of clonidine. The pontomedullary area is considered to be the main initial target of this drug. Obviously, the IOP-lavering mechanism of delta 9-THC is different from that of clonidine.