Effect of melatonin different time administration on the development of diet-induced obesity in rats

Ischemic stroke, obesity, and the anti-inflammatory role of melatonin

Obesity is a predominant risk factor in ischemic stroke and is commonly comorbid with it. Pathologies following these conditions are associated with systemic and local inflammation. Moreover, there is increasing evidence that the susceptibility for ischemic brain damage increases substantially in experimental models of ischemic stroke with concomitant obesity. Herein, we explore the proinflammatory events that occur during ischemic stroke and obesity, and we discuss the influence of obesity on the inflammatory response and cerebral damage outcomes in experimental models of brain ischemia. In addition, because melatonin is a neurohormone widely reported to exhibit protective effects in various diseases, this study also demonstrates the anti-inflammatory role and possible mechanistic actions of melatonin in both epidemic diseases. A summary of research findings suggests that melatonin administration has great potential to exert an anti-inflammatory role and provide protection against obesity and ischemic stroke conditions. However, the efficacy of this hormonal treatment on ischemic stroke with concomitant obesity, when more serious inflammation is generated, is still lacking.

The effects of melatonin administration in different times of day on the brown adipose tissue in rats with high-calorie diet-induced obesity

The aim of our study was to determine morpho-functional state (area of nucleus, brown adipocytes and also area and number of lipid droplets in each cells, general optical density of tissue) of brown adipose tissue in rats with high-calorie (high fat) dietinduced obesity after melatonin administration in different time of the day (morning and evening). Melatonin was administered daily by gavage for 7 weeks in dose 30 mg/kg either 1 h after lights-on (ZT01) or 1 h before lights-off (ZT11) rats with high-calorie diet (HCD). Besides morphometric parameters as well were measured related visceral fat weight and related brown adipose tissue mass. Rats with HCD had huge changes in brown adipocytes morphology, which summarized in become resembles of classical white adipocytes: grown lipid droplets and cells area, but goes down lipid droplets number and optical density of brown adipose tissue. In general brown adipose tissue with above mentioned characteristic from HCD rats lose their ability to conduct strongly thermoproduction function. After melatonin used in rats with HCD arise leveling of pathological changes, which associated with consumption of HCD. Namely, in groups HCD ZT01 and HCD ZT11 we obtain decreased cells and lipid droplets area, increased lipid droplets number and optical density of brown adipose tissue, in relation to group HCD. Therese received changes has evidence about functionally active brown adipose tissue state, which can also dissipate of exceed energy (lipids – triacylglycerols) amount into whole organism during heat production for avoid to its storage in white adipose tissue and in outside adipose tissue. In addition, evening administration of melatonin (group HCD ZT11) demonstrate more activated state of brown adipose tissueand also related visceral weight gain less, than morning(group HCD ZT01). In conclusions, melatonin influence on morpho-functional state brown adipose tissue in rats with HCD, moreover evening administration can use for obesity therapy via its strong action on activate brown adipocytes.