LIPOPOLYSACCHARIDE-INDUCED FEVER IN RATS PROLONGED BY A NEEDLE PRICK

We studied the effect of an abdominal prick with a needle on LPS-induc ed fever in freely-moving rats. LPS was injected intraperitoneally by the following 3 methods: 1) through a hypodermic needle pricked into t he abdominal cavity, 2) through a catheter chronically indwelt in the abdominal cavity, and 3) through a catheter chronically indwelt in the abdominal cavity immediately after an abdominal prick was made. In th e second method, core body temperature (T-b) began to rise about 1 h a fter the injection, reaching a maximal level at around 2.5 h and decre asing gradually thereafter. In the first and third methods, T-b rose a gain to make a second peak after making the first peak of fever. This was the same when LPS was injected through a hypodermic needle pricked into the abdominal cavity under restrained condition. These results s uggest that the abdominal prick with a needle is responsible for the d evelopment of the second peak (or prolongation) of LPS-fever in rats.