Hexarelin promotes the survival of retinal ganglion cells after optic nerve transection.

OBJECTIVE

Hexarelin is a growth hormone secretagogue receptor type 1a agonist with a potent anti-apoptotic effect. We studied the neuroprotective effect of hexarelin on the survival of retinal ganglion cells (RGCs) in the retina following optic nerve transection (ONT).

MATERIALS AND

METHODS

Golden hamsters of 8-9 weeks old were used. For 7 days following ONT with one dose of drug, hamsters were injected with single dose of saline, 25 μg/kg, 50 μg/kg, and 100 μg/kg hexarelin daily for 5 days. For 7 days after ONT with two doses of drugs, saline, 100 μg/kg and 150 μg/kg hexarelin were injected twice daily for 5 days. Survival of RGCs was quantified by immunostaining with Tuj1 antibody in retina whole mount.

RESULTS

Single daily doses of 25 μg/kg, 50 μg/kg, and 100 μg/kg hexarelin dose dependently and significantly increased the survival of RGC. The survival rates of RGC in saline, 25 μg/kg, 50 μg/kg, and 100 μg/kg hexarelin-treated hamsters were 51.2%, 62.4%, 68.5%, and 74.6%, respectively, in 7 days ONT. Two daily doses of saline, 100 μg/kg and 150 μg/kg hexarelin promoted survivals to 72.9%, 91.4%, and 109.2%, respectively, in 7 days ONT.

CONCLUSIONS

Single daily doses of hexarelin dose dependently increased the survival of RGC. Two daily doses of hexarelin increased RGC survival further and 150 μg/kg hexarelin twice daily is optimal for the survival of RGC.