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Research ArticleOpen Access

Week off Two days’ Model on Analgesic Efficacy of Chronic Administration of Morphine in Mice

Volume 6 - Issue 5

Hsi-Hsien Chou2,3* and Shoei-Yn Lin-Shiau*1

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    • 1School of Dentistry, Chung Shan Medical University, Taiwan
    • 2School of Medicine, Chung Shan Medical University, Taiwan
    • 3Department of Neurology, Chung Shan Medical University Hospital, Taiwan

    *Corresponding author: Shoei-Yn Lin-Shiau, School of Dentistry, College of Oral Medicine, Chung Shan Medical University, No.110, Sec1.Jianguo N. Road, Taichung, Taiwan

Received: July 04, 2018;   Published: July 17, 2018

DOI: 10.26717/BJSTR.2018.06.001426

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Abstract

Morphine is an important analgesic pain control for the patients. The unwanted morphine analgesic tolerance limited its using. In this study, we attempted to improve the effectiveness of morphine and delayed morphine tolerance by intermittent administrations of morphine. Moreover, we have designed a new composite for management of pain, e.g. combination (GTPm) of green tea polyphenols (GTP, 30 mg/kg/day) with memantine (3mg/kg/day). The results showed that morphine (I.P. injection, 10 mg/kg/day) treated mice received morphine for consecutive five days followed by two days’ off can maintain analgesic tail flick test after long-term (54 days) administration of morphine.

The hot plate analgesic test showed that GTPm enhanced analgesic effects of morphine (10mg/kg) but not with the higher doses of morphine (15 mg/kg and 30mg/kg), suggesting that GTPm has a biphasic influence on morphine analgesic effects in hot plate test. Moreover, capsaicin-induced orofacial pain test showed that GTPm also enhanced morphine analgesic effects even as long as at day 102th. The mice at this stage of chronic prolonged administration of morphine have revealed behavioral changes by markedly increased in locomotor and jump activities and decreased in rest time. The mechanism behind this prolonged antinociceptic efficacies of morphine in capsaicin-induced orofacial pain required further investigation. In conclusion, week off two days model of morphine administration attenuated morphine tolerance in tail flick pain test and capsaicin induced orofacial-pain in mice.

Keywords: Morphine Tolerance; Intermittent Chronic Administration; Combination (GTPm) of GTP and Memantine; Neuroinflammation; NMDA Receptor

Abbreviations: GTP: Green Tea Polyphenol; NMDA Receptors: N-Methyl- D-Aspartate Receptors

Abstract | Introduction | Materials and Methods | Results | Discussion | Conclusion | Acknowledgement | References |