SYSTEMIC ANTIINFLAMMATORY EFFECT INDUCED BY ANTIDROMIC STIMULATION OFTHE DORSAL ROOTS IN THE RAT

Neurogenic inflammation and other local efferent functions of the caps aicin-sensitive nerve endings is well established. Here, we describe e vidence for a systemic neurogenic anti-inflammatory effect initiated i n the rat by this local response. A preceding local neurogenic inflamm ation induced by antidromic Stimulation of lumbar dorsal roots inhibit ed a subsequent inflammatory response due to antidromic stimulation of the contralateral dorsal roots or evoked by subplantar carrageenin in jection or instillation of capsaicin solution into the eye. Initiation of these anti-inflammatory responses were prevented by degeneration o f the capsaicin-sensitive afferents after perineural capsaicin pre-tre atment, but not by bilateral adrenalectomy. These results demonstrate an unorthodox:new type of neurohumoral regulatory mechanism of sensory fibres and provide a possible mode of action for the anti-inflammator y effect of counter-irritation and acupuncture.