[Age-related changes of exercise capacity and some biochemical indices of rat muscles under influence of different light conditions and pineal preparations].

The influence of different light conditions (standard--12 h light : 12 h darkness-- LD; 24-hour constant light--LL, light deprivation--DD, natural light regimen of the North-West of Russia--NL) and substances with geroprotective effect (melatonin and epitalon) on age-related dynamics of exercise capacity, lactate dehydrogenase (LDH) isoenzymes spectrum, enzymatic and non-enzymatic system of generation and utilization of oxygen reactive substances, activity of key antioxidant enzymes in skeletal musculature were investigated during 2 years. The decrease of exercise capacity, changes of energy production strategies and antioxidant protection during animals ageing in dependence on different light conditions was found. LL lead to earlier decrease of exercise capacity with synchronous increasing content of less effective anaerobic LDH fraction and decreasing of catalase activity in comparison with DL. Similar decreasing of exercise capacity, changes in LDH spectrum and antioxidant status in NL condition coincide in time with autumn season what indicates that seasonal changes of illumination is natural disturber of circadian rhythm. Melatonin and epitalon applied from 4-month age did not influence on exercise capacity in young rats. Both substances had similar stimulate effect on age-related physical activity of mature and senescent animals such as reducing of exercise capacity depression and normalization of antioxidant protection.