Bacterial infection ( [formula omitted]) stimulates fever, metabolic rate and brown adipose tissue activity in the Guinea pig

The objective of this study was to assess whether bacterial infection stimulates oxygen consumption and brown adipose tissue (BAT) activity. Guinea pigs infected with Legionella pneumophila showed marked fever and a significant (33%) increase in resting oxygen consumption (VO 2), 24th after infection. At this time, food intake and body weight were normal and the in vitro thermogenic activity of BAT taken from infected animals was elevated by 64% above that of control guinea pigs. VO 2 and BAT activity fell to control values by 48h as infected animals became moribund and over this period food intake was markedly reduced. Bacterial infection is frequently associated with fever, which is generated by both increased heat production and reduced heat loss. Hypermetabolic responses to infection and injury may involve similar mechanisms to non-shivering thermogenesis (1,2,3). Studies on laboratory rodents have tended to concentrate on the use of bacterial endotoxins (eg 2), which do not mimic all aspects of the responses to infection, particularly since they are short-lived and are rapidly tolerated. We report here the results of a study using a pneumonia infection with Legionella pneumophila in the guinea pig. The objective of the study was to determine whether bacterial infection which causes weight loss is associated with hypermetabolism and activation of BAT.