Burn-induced alterations in feeding, energy expenditure, and brain amine neurotransmitters in rats.

A 30% body surface area, open-flame, full-thickness burn of adult rats induced a 4-day period of anorexia that was followed by hyperphagia beginning on postburn day 10. The hyperphagic burned rats also exhibited increased resting energy expenditure and no gain in body weight, suggesting hypermetabolism. Plasma levels of immunoreactive insulin and albumin were decreased in both groups of burned rats; immunoreactive pancreatic glucagon concentrations were elevated only in the anorectic burned rats. Plasma levels of epinephrine were elevated in the hyperphagic burned rats. In the brain, dopamine metabolism appeared to be increased in the corpus striatum, nucleus accumbens, and amygdala of anorectic burned rats; norepinephrine levels were elevated in the hypothalamus and nucleus accumbens of the hyperphagic-hypermetabolic rats. These data indicate that this animal model of major burn trauma exhibits anorexia, hyperphagia, catabolism, and hypermetabolism. Furthermore, elevated dopamine metabolism appears to be associated with the anorexia, while the hyperphagia-hypermetabolism may be mediated by norepinephrine.