A Study Of The Effect Of LIF (Leukemia Inhibitory Factor) On GAP-43 (Growth Associated Protein-43) Expression In The Mice With Chronic Ocular Hypertension Model

Objective: Based on the mice with chronic ocular hypertension model, toobserve the effect of LIF (leukemia inhibitory factor) on GAP-43 (growth associatedprotein -43) expression in mouse RGCs (retinal ganglion cells) and other parts of theRetinal, and investigate the LIF neuroprotective effect on RGCs. To supply aneffective auxiliary clinical treatment for chronic diseases with unclear loss of RGCs(such as Glaucoma, Retinitis Pigmentosa, etc.).Methods: 60 normal mice without any eye diseases (60 eyes) were randomlydivided into the control group (20 mice, 20 eyes), the chronic ocular hypertensiongroup (COH group 20mice, 20eyes), the LIF treatment group (20mice, 20eyes). Thesethree groups were subdivided into group 0 day (the day before treatment), 1 day, 7days, 14 days after treatment (5 mice per group, 5 eyes). To establish a reliable mousemodel of chronic ocular hypertension by burning the episcleral veins, aqueousoutflow veins. After the success of the model (elevated intraocular pressure stabilityafter 1 week), intravitreal injection of 0.5ul /g LIF was operated to mice eyes of theLIF treatment group. Respectively as 0day, 1day, 7days, 14days, the eyes wasremoved, fixed, embedded in paraffin, sliced, then HE staining andImmunohistochemical staining. The retina morphological change was observed underlight microscope, then to quantify RGCs and measure GAP-43 expression in grayanalysis by applications for medical image analysis system with statistical analysis.Results:1.Intraocular Pressure: The IOP in mice eyes between the COH group and the LIFtreatment group is no significant difference (P>0.05) before treatment andimmediately after treatment, but higher than the control group; and the LIF treatmentgroup shows the lower (P<0.05) IOP but not significant than the COH group in thesubsequent 1day, 7days, 14days, and higher (P<0.05)than the normal control group.2. Histology Observation: Histological changes in the COH group as the RNFL(retinal nerve fiber layer) and the IPL (inner plexiform layer) showing edema in early;the terminal IPL atrophy, thinning, and loss of a large number of RGCs. The LIFtreatment group shows the faster edema regression, atrophy and the loss of RGCs notobvious. 3. RGCs count results: Compared with the LIF treatment group and the COHgroup, there is no significant difference (P> 0.05) in RGCs number at 0 day and 1 day,but the number was less than the control group. The RGCs number of the LIFtreatment group was significantly increased in the subsequent 7days, 14days than theCOH group, but less than the normal control group, the difference was significant(P<0.05).4. Immunohistochemical observations: GAP-43 expression in the RNFL, RGCs,and the IPL in each group. Through analysis and comparison of gray scale, theexpression of GAP-43 is visible in early COH group then gradually decreased, finallythe expression close to normal; In the LIF treatment group, the expression of GAP-43increased steadily during the observation period ,the difference was significant(P<0.05).ConclusionConclusion:1.The retinal changes in pathology and intraocular pressure confirm that mousemodels of chronic ocular hypertension were successful and reliable.2. LIF can promote increased expression of GAP-43 in mouse models of chronicocular hypertension.3. LIF has neuroprotective effect on RGCs in mouse models of chronic ocularhypertension.