Reduced nociceptive behavior in islet amyloid polypeptide (amylin) knockout mice

Islet amyloid polypeptide (LAPP or amylin) is predominantly expressed by insulin cells, but occurs also in primary sensory neurons in the rat. Here, using mice targeted for a null mutation in the IAPP gene,we establish murine expression of IAPP in sensory neurons; its distribution in a population of calcitonin gene-related peptide-containing neurons in the spinal cord and dorsal root ganglion is similar to that previously described in the wt. We also report the IAPP mutant mice display a reduced pain response in the paw formalin test. Adjuvant-induced joint inflammation was not altered in LAPP mutants, arguing against a peripheral inflammatory abnormality. These findings lead us to suggest that IAPP has a pro-nociceptive function in primary sensory neurons. (C) 1998 Elsevier Science B.V. All rights reserved.