engleski

Brown adipose tissue thermogenesis: relation to constitutive differences in serotonin homeostasis

Brown adipose tissue (BAT) is a thermogenic organ with a large ability to convert chemical energy into heat. It has been suggested that increasing of BAT energy expenditure might protect against obesity. A bioamine serotonin (5- hydroxytriptamine, 5HT) acts as anorexigenic neurotransmitter, but peripheral inhibition of 5HT activity seems to reduce obesity by promoting BAT thermogenesis, pointing to the opposite function of central and peripheral 5HT in the regulation of energy homeostasis. To better understand the integrative role of 5HT in pathology of obesity, we use Wistar-Zagreb 5HT rats, a model consisting of two sublines with constitutionally altered 5HT homeostasis (high- 5HT and low-5HT subline), developed by selective breeding toward extreme activities of platelet5HT transporter. Rats from the high-5HT subline have increased body weight and visceral adiposity in comparison with low-5HT animals. Using infrared thermography, here we compared BAT thermogenesis between rats from 5HT-sublines. We also examined relative BAT mass and BAT expression of uncoupled protein-1 (UCP-1), a mitochondrial protein responsible for dissipating energy into heat. Adult obesity phenotype of animals from the high- 5HT subline was accompanied by lower BAT weight, lower BAT UCP-1 mRNA levels and lower BAT thermogenesis. In neonatal rats no significant differences between 5HT-sublines were observed. In response to high-fat diet, animals from the two sublines showed similar increase in BAT thermogenesis. In conclusion, our findings obtained in an original rodent model support a notion that increased peripheral 5HT activity reduces BAT thermogenesis and thus contributes to obesity phenotype.

Obesity ; body weight ; Wistar-Zagreb 5HT rats ; brown adiposse tissue termogenesis ; energy balance

nije evidentirano