The effect of melatonin on muscle glycogen level after the exhaustion training in rats

ABSTRACTRecovery period after exercise is especially important for athletes. In thisperiod, carbohydrate stores serve as main fuel to re-acquisition of contractionperformance.The aim of this study is to investigate the effect of melatonin on muscleglycogen level during the recovery period in sedantery and training rats.In this study, three-months male Wistar rats were divided into four groups assedantery control (C), sedantary melatonin (M), training (T) and training groupinjected melatonin (MT). After all the animals were administered two dayshabituation period, training (T and MT) groups were applied to six weeks swimmingexercise. One day after the last swimming exercise in trained rats and last habituationpractice in sedantery animals, all of them were exposed to exhausting swimmingexercise. Blood lactic acid levels measurements were done by using the bloodsamples oobtained from tail vein after 5 min. the exhaustion. In additionally that,melatonin injection were performed in M and MT groups as two times atimmediately after the exhaustion and after 24 h. Melatonin were injected at 3mg/kg/day dose by dissolved in % 10 ethanol. C and T groups were injected 0.1 mlsubcutaneous ethanol without melayonin. 48 h after exhaustion, melatonin andglucose levels measurements were done using the blood samples obtained from rataortas. Finally, M. epitrochlearis and M. soleus were dissected immediately and themuscle glycogen levels were determined using these samples.Our results showed that plasma lactic acid level of group T was significantlylower than that of group M and C. Plasma melatonin level of group MA was higherthan the other three groups. The concentrations of plasma glucose significantlyincreased in T and MT groups compaired with M group. Epitrochlearis muscleglycogen level was higher in MT goup compared with the M group. No significantdifferences were found among other groups. It was observed that M. soleus glycogenlevel of group T was higher than that of group C. In the comparasion of all groups interms of epitrochlearis and soleus muscle glycogen levels, soleus muscle glycogenlevel was much higher than epitrochlearis muscle in group T.We concluded that using exogenous melatonin results in increase theglycogen level in fast twich muscles althought training effect is prominent in slowtwich muscles.Key words: Exhaustion, swimming exercise, melatonin, glycogen, recovery, rat.v