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J.D. Crandall, C. Borlongan, S. Matragoon, G. Liou; Intraocular Pressure Lowering and Neuroprotective Effects of (–) &916;9 Tetrahydrocannabinol in an Experimental Model of Ocular Hypertension . Invest. Ophthalmol. Vis. Sci. 2004;45(13):903.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose:To observe the effects of (–) Δ9 Tetrahydrocannabinol (THC) on intraocular pressure (IOP) and retinal ganglion cell (RGC) number in an experimental model of ocular hypertension. Methods:An experimental model of chronic, moderately elevated IOP was produced in the left eye of fourteen Sprague–Dawley rats by cauterization of two episcleral veins. The contralateral eye served as the control. Seven randomly chosen operated rats received weekly intraperitoneal injections of THC at 5mg/kg and the others received vehicle. IOP was measured weekly using a Tono Pen XL on anesthetized animals. Bilateral injection of Di–I into the superior colliculus was performed 1 week before killing to label retinal ganglion cells in a retrograde fashion. Left and right eyes were compared at 12 regions (6 central and 6 peripheral at 100X) of the whole–mount retinas in all animals. Approximately 15,000 cells per retina were counted in each right eye. Results:IOP was elevated in all left eyes one day after the operation and remained elevated in the vehicle–treated rats throughout 20 weeks. In the THC–treated rats, IOP elevation was diminished one week after the operation and remained reduced. In the left eye of the vehicle–treated animals, there was a loss of ∼50% and 40% of the RGCs in the peripheral and central retina, respectively. The RGC loss in the left eye of the THC–treated animals was reduced to 10–20%. Conclusions:THC lowered intraocular pressure in eyes which had undergone episcleral vein cauterization. In addition neuroprotective effects were also seen with the reduction in ganglion cell loss in the animals in the treated group. This study provides supporting evidence that IOP lowering and neuroprotection are effects of THC treatment.
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