CENTRAL PYROGENIC ACTION OF SALMONELLA TYPHOSA LIPOPOLYSACCHARIDE INJECTED INTO THE LATERAL CEREBRAL VENTRICLE IN CATS

¹ Seth G. S. Medical College, Bombay, India
² Department of Pharmacology, University of Utah College of Medicine, Salt Lake City, Utah

A method has been described for continuous recording of deep body temperature in chronic unrestrained cats with permanently implanted retroperitoneal thermocouples and cerebral ventricular cannulas.

Diurnal variation in body temperature was determined in control experiments, and pyrogenic dose-effect and volume-effect relationships were established for intraventricular S. typhosa lipopolysaccharide. Characteristics of fever responses and development of tolerance to endotoxin were compared for intraventricular, intrathecal (C-1), and intravenous routes of administration. Intraventricular endotoxin continued to elicit fever after low-cervical spinal cord transection. Ablation of the medullary emetic chemoreceptor trigger zone (CT zone) did not interfere with the pyrogenic and emetic responses evoked by endotoxin.

It is concluded that bacterial lipopolysaccharide probably acts on receptor sites, with different physiological properties, at various levels in the central nervous system.