Intraneuronal substance P contributes to the severity of experimental arthritis.
There is evidence that substance P is a peptide neurotransmitter of some unmyelinated primary afferent nociceptors and that its release from the peripheral terminals of primary afferent fibers mediates neurogenic inflammation. The investigators examined whether substance P also contributes to the severity of adjuvant-induced arthritis, an inflammatory disease in rats. They found that, in the rat, joints that developed more severe arthritis (ankles) were more densely innervated by substance P-containing primary afferent neurons than were joints that developed less severe arthritis (knees). Infusion of substance P into the knee increased the severity of arthritis; injection of a substance P receptor antagonist did not. These results suggest a significant physiological difference between joints that develop mild and severe arthritis and indicate that release of intraneuronal substance P in joints contributes to the severity of the arthritis.
D000818:Animals; D001168:Arthritis / Q000139:chemically induced / Q000503:physiopathology*; D004311:Double-Blind Method; D006614:Hindlimb; D007596:Joints / Q000187:drug effects / Q000294:innervation / Q000503:physiopathology; D009475:Neurons, Afferent / Q000502:physiology; D051381:Rats; D013373:Substance P / Q000494:pharmacology / Q000502:physiology*
D013373:Substance P