CULTURED RAT SENSORY NEURONS EXPRESS FUNCTIONAL TACHYKININ RECEPTOR SUBTYPE-1, SUBTYPE-2 AND SUBTYPE-3

The neuropeptide substance P (SP) is known to play a key role in perip heral nociceptive processes. We investigated the in vitro pharmacologi cal characteristics of functional tachykinin receptors expressed in do rsal root ganglia (DRG) sensory neurones by analysing intracellular fr ee calcium concentration changes induced after stimulation by SP or sp ecific tachykinin agonists. We observed that about 37% of the tested n eurones were responsive to either SP or an NK1-, NK2- or NK3-specific agonist. Tachykinin-responsive neurones had a small soma diameter (<20 mu m) and were sensitive to capsaicin. These results suggest the pres ence of NK1, NK2 and NK3 receptors in noxious sensory neurones. (C) 19 98 Elsevier Science Ireland Ltd.