PMID-sentid Pub_year Sent_text comp_official_name comp_offsetprotein_name organism prot_offset 6274671-1 1981 The effect of beta-endorphin and morphine on neuromuscular twitching of the vas deferens was examined in rats of 10-120 days of age. Morphine 33-41 arginine vasopressin Rattus norvegicus 76-79