Aspectos histológicos do tecido adiposo marrom de ratos obesos e não-obesos suplementados cronicamente com o óleo de castanha-do-brasil

Abstract

Brown adipose tissue (BAT) is able to increase energy expenditure via thermogenic process. Nutritional compounds, presented in foods, such as Brazil nut - Bertholetia excelsa (Be), have the potential to cause satiety, increase energy expenditure and have anti-obesity actions. The effects of Be consumption on BAT are unknown and may be involved in increased energy consumption and body weight control. In the present study, we evaluated the impact of chronic Be oil supplementation on histology and lipid deposition in the BAT of obese and non-obese male and female rats. Hypothalamic obesity was induced by neonatal administration of monosodium L-glutamate (MSG; 4g/Kg) in male and female rats. The solution Non-obese or control rats (CTL) received equimolar saline solution. After weaning week, CTL and MSG were randomly assigned to non-supplemented (NS) and Be oil supplemented groups (1mL/Kg; 3 times/8 weeks). At 90 days of life, body weight (BW), nasal anal compliance (NAL), adiposity and plasma glucose and triglycerides were obtained. The TAM was removed, weighed and histologically processed to analyze the number and areas of nuclei, areas of brown adipocytes and lipid classification. Fatty acid methyl esters were evaluated in Be oil to quantify the fatty acid profile. Treatment with MSG, in males and females, causes an increase in TAM weight, reducing the number of nuclei and increasing lipid deposition compared to CTL. Chronic supplementation with Be-oil caused hypertriglyceridemia in male MSG-obese rats, without altering adiposity. On the other hand, in MSG-obese females, Be oil supplementation reduced adiposity without modifying metabolic parameters. Be oil supplementation increased the number of BAT nuclei, especially in the non-obese female group, suggesting an influence of sex and obesity on this effect. However, in all groups, regardless of sex or obesity, Be oil supplementation did not significantly modify lipid deposition or adipocyte area in BAT. A high content of oleic fatty acid followed by linoleic fatty acid and, to a lesser extent, palmitic and stearic acids were conferred. Therefore, under thermoneutrality conditions and in the face of standard diet consumption, chronic supplementation with Be oil does not alter BAT lipid deposition, indicating no effect on thermogenesis in obese and non-obese rodent