Long Term Interactions between Tea Polyphenols, Memantine and Morphine on Orofacial Pain in Mice

Abstract

Abstract Morphine is one of the analgesics used in dental clinics, but morphine tolerance is a severe side effect. We attempted to delay the development of morphine tolerance by a week off two days model and enhanced the analgesic effects of morphine by Green Tea Polyphenols (GTP), memantine (m) either alone or in combination (GTPm). The results obtained showed that morphine was very effective in attenuating the orofacial pain induced by capsaicin in mice even after prolonged treatment in 92 days. GTP, memantine and GTPm all were effective in attenuating at the late stage of prolonged treatment in 92 days on the orofacial pain of mice. The behavioral changes in mice after chronic treatment of morphine included the increased locomotor activities and decreased the exploratory activities in the open field of elevated plus maze which could be apparently minimized by GTPm. In conclusion, we have demonstrated that week off two days model and the combination use with GTPm could be successfully in enhancement of morphine analgesic effect on orofacial pain as long as for 3 months in the mice. Keywords: Chronic Administration; GTP; GTPm; Memantine; Morphine; Orofacial Pain; Week off Two Days