[Analgesic effect of kappa-opioid receptor agonist].

Opioid receptors are classified into at least 3 types(mu, delta, kappa). Among these types, the kappa receptor system has become most attractive. This receptor system is significant to our understanding of opioid pharmacology and the potential development of novel therapeutic agents, and its importance extends beyond the clinical issues of pain and its relief. Endogenous opioid systems have been proposed as secondary or delayed brain injury factors, largely on the basis of the therapeutic efficacy of opioid receptor antagonists or agonists. Recent our experimental study has demonstrated that the novel kappa opioid agonist RU 599 has neuroprotective effect on traumatic and ischemic brain edema and analgesic effect. In this short review, various properties of the kappa opioid receptor agonist concerning analgesic function, neuroprotection and other studies are briefly described.