Effect of latanoprost on intraocular pressure in mice lacking the prostaglandin FP receptor

Purpose. To determine whether latanoprost lowers IOP in prostaglandin FP receptor knockout mice. Methods. Mean IOP difference between treated and untreated fellow eyes was measured on three separate occasions, 2 hours after a 200-ng dose of latanoprost to the right eye of homozygous (n=9) and heterozygous (n=15) FP knockout mice. C57BL/6 (n=10) and NIH Swiss white mice (n=17), which have normal FP receptor expression, provided the control population. The investigator was masked to the genotype of the FP knockout mice at the time of IOP measurement. Results. Latanoprost had no effect on IOP in the homozygous FP knockout mice, with an average difference in IOP between treated and untreated fellow eyes of +0.25 mm Hg and a 95% confidence interval (CI) for the difference between means of -0.019 to +0.69. In contrast, latanoprost reduced IOP in the treated eye of the heterozygous FP knockout, C57BL/6, and Swiss white mice with mean differences and 95% CI of the difference in means of -0.52 (-0.91 to -0.14), -1.38 (-2.1 to -0.70), and -1.29 (-1.78 to -0.79) mm Hg, respectively. Conclusions. FP receptor signaling plays a crucial role in the early IOP response to latanoprost in the mouse eye.