Effect of simultaneous CGRP and PGF(2alpha) on the outflow facility in the rabbit eye

Both calcitonin gene-related peptide and prostaglandins have an influence on the intraocular pressure in the eye. In this study, the effects of low intracameral doses (20 ng and 50 ng) of calcitonin gene-related peptide, prostaglandin F(2alpha), and simultaneous dosing of both, on the outflow facility were studied in the rabbit. Calcitonin gene-related peptide increased the outflow facility at both 20 and 50 ng doses, while prostaglandin F(2alpha) increased it only at a 50 ng dose. Further, simultaneous administration of both at 50 ng doses increased the outflow facility and showed a slight additive effect with these two compounds. The results further indicate that these compounds have a different mechanism of action. Calcitonin gene-related peptide seems to increase the conventional outflow (trabecular outflow), while prostaglandin F(2alpha) tends to increase the unconventional outflow (uveoscleral outflow).