PITUITARY ADENYLATE CYCLASE-ACTIVATING PEPTIDE IS UP-REGULATED IN SENSORY NEURONS BY INFLAMMATION

THE neuropeptide pituitary adenylate cyclase-activating peptide (PACAP ) is expressed in sensory neurons. Expression of several neuropeptides is up-regulated in sensory neurons following inflammation. To examine whether also PACAP expression is regulated by inflammation, PACAP exp ression in L5 dorsal root ganglion (DRG) was determined, using in situ hybridization, after unilateral adjuvant-induced inflammation in the rat paw. At 12 h and day 3, but not day 21, the percentage of neurons expressing PACAP mRNA was greater in the innervating L5 DRG. Similarly , PACAP mRNA expression in individual neurons was higher in the innerv ating L5 DRG at 12 h and day 3, but not day 21. Up-regulated PACAP exp ression following adjuvant injection suggests a role for PACAP in infl ammation. (C) 1998 Lippincott Williams & Wilkins.