The effect of interleukin-1 beta on the efferent activity of the vagus nerve to the thymus.

The effects of intravenous (i.v.) administration of recombinant human interleukin-1 beta (rhIL-1 beta) and human interleukin-1 beta-fraction (hfrIL-1 beta) on the activity of vagal efferent fibers innervating the thymus were observed in urethane-anesthetized rats. An i.v. injection of 10 ng rhIL-1 beta or hfrIL-1 beta caused a similar degree of increase in the efferent activity, which lasted longer than 2 h. The least effective dose was 1 ng and dose-dependent responses were observed after i.v. injection of rhIL-1 beta at doses of 1 ng, 10 ng and 100 ng. The IL-1 beta-induced activation of efferent activity of the vagal branch to the thymus implicates their involvement in the neural modulation of the thymic function.