Effects of bacterial lipopolysaccharide on central monoamines and fever inthe rat: involvement of the vagus

Lipopolysaccharide (LPS) is known to produce a number of central and neuroe ndocrine effects but the mechanisms involved are still unclear. This study was done to investigate the possibility that LPS-induced fever and activati on of central monoamines are mediated through the vagus. Adult-male rats we re subjected to sub-diaphragmatic vagotomy (SDV), or sham operation and tre ated with saline or LPS in saline (10 mu g/kg bw) 2 h later. Rectal tempera ture was monitored at half-hourly intervals for 5 h after which the animals were sacrificed and monoamine concentrations in hypothalamic nuclei were m easured using HPLC-EC. SDV delayed the rise in rectal temperature induced b y LPS by 1 h when compared to Sham animals. It also increased the concentra tions of monoamines in the paraventricular nucleus of both Sham and SDV rat s. This indicates that routes other than the vagus probably mediate LPS' ac tions on the central nervous system. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.