The relationship between oxidative stress and bcl-2 in hippocampus of older rats

In aging process, the production of radicals in several tissues increases while antioxidant capacity reduces. This fact is observed in neurodegenerative diseases in various brain regions including hippocampus. Melatonin, which is known as a powerful scavenger of radicals, significantly decreases with aging. Curcumin is a polyphenol which has anti-inflammatory, antiproliferative and antioxidant effects. Bcl-2, which takes a role in regulation of cellular redox state, is identified with antioxidant and antiapoptotic features. The aim of the present study was to investigate the impact of melatonin and curcumin treatments on MDA which is an oxidative stress indicator; GSH, which function as an antioxidant system indicator; and bcl-2 which is a regulator of cellular redox status. In this respect, MDA, GSH and bcl-2 was assessed by using TBARS, modified Ellman and Western Blott techniques, respectively. Following the approval of the ethical committee, Wistar rats divided 5 groups (13 month-aged, n=30) and they were housed under laboratory conditions with 12 h-light/dark cycle. These groups were control group (1% ethanol-PBS sc, at 17:00, for 30 days), dimethyl sulfoxide (DMSO 100?l/bw ip, at 17:00, for 30 days), melatonin (MEL-10mg/kg+ethanol-PBS sc, at 17:00, for 30 days), curcumin (CUR-30mg/kg+DMSO ip, at 17:00, for 30 days) and MEL+CUR.88Comparing to the PBS-control group, MDA levels in hippocampus significantly decreased in treatment groups of MEL, CUR, MEL+CUR (p<0,05). Furthermore, the level of GSH increased in CUR and MEL+CUR groups, compared to PBS and DMSO groups (p<0,05). MDA and GSH were negatively correlated in CUR and MEL+CUR groups (r(6)= -0,74; p=0,05 ve r(6)= -0,78; p<0,05, respectively). Bcl2/beta actin ratio significantly decreased in CUR, MEL+CUR and DMSO groups, compared to PBS and MEL groups (p<0,05). In sum, findings indicated that the treatment of melatonin alone decreased radical damage in hippocampus. However, the treatment of curcumin alone and of curcumin and melatonin together not only decreased the radical damage, but they also increased GSH level in hippocampus. Furthermore, the treatment of curcumin alone and of curcumin and melatonin together decreased bcl-2 level. Consequently, the treatment of the antioxidants such as melatonin and curcumin in adulthood might be an effective protector against neurodegenerative damages in hippocampus through the aging process.Keywords: Aging, oxidative stress, melatonin, curcumin, hippocampus, bcl-2