CENTRALLY ADMINISTERED BACTERIAL LIPOPOLYSACCHARIDE DEPRESSES FEEDINGIN RATS

Bacterial lipopolysaccharide (LPS) suppresses feeding in rats when adm inistered peripherally in the microgram range. In the present study, t he effects of LPS (Escherichia coli serotype 0111 : B4) on the central regulation of feeding in rats maintained ad lib was investigated. Int racerebroventricular (ICV) microinfusion of LPS (0.1 to 1000 ng/rat) s uppressed the short-term (2-h) and long-term (nighttime and total dail y) food intakes, dose dependently. Computerized analysis of behavioral patterns demonstrated a significant reduction of meal size during the nighttime, whereas meal frequency and meal duration were also decreas ed, but not significantly. Water intake and locomotor activity also de creased. Intraperitoneal administration of LPS in doses equivalent to those administered centrally had no effect on food intake. The results suggest that centrally administered LPS acts directly in the central nervous system (CNS) to depress feeding.