Anti-scarring effect of rapamycin in rabbits following glaucoma filtering surgery

Abstract

To study the anti- scarring effect of rapamycin in rabbits receiving glaucoma filtering surgery. Ninety-six Chinchilla rabbits were randomized equally into 3 rapamycin treatment groups and one control group. All the rabbits underwent trabeculectomy, after which the rabbits in the 3 rapamycin groups were treated with eye drops containing 1%, 3%, or 5% rapamycin in the operated eyes, and those in the control groups were given castor oil 4 times a day. The intraocular pressure (IOP) and inflammatory reaction in the treated eyes were observed, and the PCNA-positive cells in the filtering bleb were detected using immunohistochemistry. RTFs isolated from the Tenon's capsule of the rabbits were cultured in vitro, and the expressions of caspase-3, caspase-8, and caspase-9 in the fibroblasts were detected after treatment with different concentrations of rapamycin. The IOP was significantly lower in rapamycin-treated group than in the control group after the surgery (P < 0.05). The counts of the PCNA-positive cells were significantly lower in rapamycin-treated rabbits than in the control group (P < 0.05). Rapamycin treatment dose-dependently increased the expressions of caspase-3 and caspase- 9 at both the mRNA (P < 0.001) and protein (P < 0.001) levels without causing significant changes in the expressions of caspase-8. Rapamycin can inhibit excessive proliferation of the fibroblasts in the filtering bleb to reduce scar formation after glaucoma filtration surgery in rabbits. Rapamycin also increases the expressions of caspase-3 and caspase-9 to induce apoptosis of the RTFs.