2020 Volume 16 Article ID: FFR191212-2
Retinitis pigmentosa (RP) is an ophthalmic disease with no fundamental cure that eventually leads to blindness. Since RP is associated with apoptosis of photoreceptor cells caused by oxidative stress, suppression of oxidative stress is expected to be effective in ameliorating RP. Since black soybean seed coat extract has high antioxidant activity, we used Chrono-Care® (Chrono-Care ® SP60, Fujicco Co., Ltd.) that contains black soybean polyphenol to investigate suppressive effects on N-methyl-N-nitorsourea (MNU) -induced retinal degeneration in rats. The antioxidant effects of 1, 2, and 4% Chrono-Care® water were measured by an OXY-adsorbent test. Female SD rats at 7 weeks of age were given a single i.p. injection of 50 mg/kg MNU and 0.2 or 2% Chrono Care ® -containing diets were freely fed from 4 weeks of age until the day of necropsy. Eyes were collected 48 hrs after MNU injection and the photoreceptor cell ratio was calculated. Using the same animal model, rats were freely fed 2% diet on the same schedule. Eyes were collected 24 hrs and 7 days after MNU injection for TUNEL and other immunostaining. In the results, concentration-dependent increase of antioxidant activity was observed. In the 2% diet combined group, retinal photoreceptor cell ratio was higher than in the MNU treated group. In the 2% diet combined group, TUNEL and anti-thymidine glycol immunostaining signals were lower than in the MNU treated group 24 hrs after MNU injection. Rhodopsin positive immunostaining was extensive in outer retina 7 days after MNU injection. In conclusion, suppressive effects of Chrono-Care ® SP60 on MNU induced retinal degeneration was demonstrated. The mode of action is potentially related to the suppression of oxidative stress in the retina. It may possibly be effective in suppressing of human RP.
