Adaptations of the aging animal to exercise: role of daily supplementation with melatonin

Abstract

The pineal gland, through melatonin, seems to be of fundamental importance in determining the metabolic adaptations of adipose and muscle tissues to physical training. Evidence shows that pinealectomized animals fail to develop adaptive metabolic changes in response to aerobic exercise and therefore do not exhibit the same performance as control-trained animals. The known prominent reduction in melatonin synthesis in aging animals led us to investigate the metabolic adaptations to physical training in aged animals with and without daily melatonin replacement. Male Wistar rats were assigned to four groups: sedentary control (SC), trained control (TC), sedentary treated with melatonin (SM), and trained treated with melatonin (TM). Melatonin supplementation lasted 16 wk, and the animals were subjected to exercise during the last 8 wk of the experiment. After euthanasia, samples of liver, muscle, and adipose tissues were collected for analysis. Trained animals treated with melatonin presented better results in the following parameters: glucose tolerance, physical capacity, citrate synthase activity, hepatic and muscular glycogen content, body weight, protein expression of phosphatidylinositol 3-kinase (PI3K), mitogen-activated protein kinase (MAPK), and protein kinase activated by adenosine monophosphate (AMPK) in the liver, as well as the protein expression of the glucose transporter type 4 (GLUT4) and AMPK in the muscle. In conclusion, these results demonstrate that melatonin supplementation in aging animals is of great importance for the required metabolic adaptations induced by aerobic exercise. Adequate levels of circulating melatonin are, therefore, necessary to improve energetic metabolism efficiency, reducing body weight and increasing insulin sensitivity.

Melatonin promotes adipogenesis and mitochondrial biogenesis in 3T3‐L1 preadipocytes

“…These events were accompanied by elevated expression of the mitochondrial genes cytc and ucp2. Moreover, melatonin increased the expression of COX IV and enhanced citrate synthase activity, as observed in skeletal muscle [42,43]. COX IV catalyzes the final step in the mitochondrial electron transfer chain and is regarded as a major regulator of oxidative phosphorylation.…”

Impact of Melatonin on Skeletal Muscle and Exercise

“…In any case, exogenous melatonin is useful as an antioxidant and an anti-inflammatory nutrient for prolonging muscle strength and adaptation during strenuous exercise in rodents and men in adulthood and aging [177][178][179][180]. Melatonin intake before and during exercise reduces glucose resistance and ameliorates antioxidant status in various situations, such as during preparatory training, in a soccer training camp, in resistance, or in high-trained athletes [181][182][183][184].…”

Melatonin multiple effects on brown adipose tissue molecular machinery

“…Melatonin has been shown to regulate BAT, acting as a recruiter and increasing its thermogenic capacity . Despite its regulatory role in other metabolic active tissues and the evidences of its interaction with BAT, little is known about its role in the metabolic thermogenic pathway either in its daily regulation or after acute challenges. The present work aimed to analyze that using pinealectomized and melatonin‐treated pinealectomized animals.…”