Modulation of morphine analgesia in alphaCGRP mutant mice

9.454> 1999 Lippincott Williams & Wilkins. Key words: # and # CGRP; Homologous recombination; Hot plate; Knock-out mice; Morphine analgesia; Tail ick Introduction The calcitonin gene-related peptide (CGRP) family includes a variety of homologous peptides with different physiological and pharmacological actions. Calcitonin and #CGRP are encoded by the same gene and are derived from alternative splicing of a common RNA precursor [1]. Each peptide is processed in a tissue-specic manner. Calcitonin (CT) is expressed in thyroid C cells and controls calcium homeostasis [2] while CGRP is present in the central and peripheral nervous system [3]. In particular, CGRP immunoreactivity is detected in spinal cord motor neurons and dorsal root ganglia [4], as well as in motor nerve endings, where it co-exists with acetylcholine [5]. Many actions have been ascribed to CGRP [6], including trophic effects on skeletal muscle [7,8]