Effects of antibodies to adipocytes on body weight, food intake, and adipose tissue cellularity in obese rats

Female Wistar rats mere fed on a high fat diet for 18 weeks, during which their energy intake increased by 25% and body weight by 50% due to a doubling of adipose tissue tissue stores. Animals were then treated with increasing doses of a sheep polyclonal antiserum to rat adipocytes on days 1-4 and 7 after which they remained untreated for 14 weeks. Antibody treatment reduced body weight by 10% and the weight of parametrial and subcutaneous adipose tissue by 30-40%, This decrease was explicable entirely in terms of a decrease in the number of adipocytes presumably due to adipocyte lysis, These favourable changes in body fat mass were accompanied by improvement in at least one metabolic factor associated with obesity-serum leptin concentrations were significantly reduced in treated animals compared with high fat controls. Genetically obese Zucker rats also showed decreases in the number of adipocytes after treatment with antibodies but in contrast to diet-induced obese rats, they showed a compensatory increase in adipocyte volume which attenuated the effects on body fat mass. These results demonstrate for the first time, the potential to treat diet-induced obesity with antibodies to adipocytes by producing longterm reductions in the number of adipocytes, with minimal side-effects. (C) 1998 Academic Press.