Evaluation of potential pro-survival pathways regulated by melatonin in a murine senescence model

We examined the effect of melatonin on pro-survival processes in three groups of mice. Untreated senescence-accelerated mice (SAMP8), melatonin-treated SAMP8 and untreated senescence-accelerated resistant mice (SAMR1) of 10 months old were studied. Melatonin (10 mg/kg) or vehicle (ethanol at 0.066%) was supplied in the drinking water from the end of the first month until the end of the ninth month of life. Differences in the Akt/Erk1-2 pathway and downstream targets were examined and no significant changes were observed, except for beta-catenin. However, sirtuin 1 expression was significantly lower in SAMP8 than in SAMR1. In addition, acetylated p53 and NFkappaB expression were lower in SAMP8 than in SAMR1. These changes were prevented by melatonin. Moreover, the concentration/expression of alpha-secretase was lower and that of amyloid beta aggregates (Abeta) was higher in untreated SAMP8 than in SAMR1. Likewise, the levels of Bid were higher, whereas Bcl-2(XL) levels were lower in SAMP8 than in SAMR1. Melatonin reduced all these changes. We conclude that melatonin improves pro-survival signals and reduces pro-death signals in age-related impairments of neural processes.