The Pharmacodynamics And Mechanism Study Of Diarylmethylpiperazine-like Agonists Of Multi-subtype Opioid Receptors

Opioids have been long-lasting used as the analgesic drugs since it was discovered.Opioid drugs like morphine,codeine,buprenorphine,fentanyl are the mainstay for the clinical treatment of moderate and severe pain in recent times.But unfortunately,they also are notorious for their severe side effects like tolerance,dependence,respiratory depression,nausea and vomiting,constipation and urinary retention after chronic use,which limit their clinical utility.Over the past decades,amount of research have been done in molecular pharmacological mechanism of opioids and opioid receptors in order to design the novel analgesic compounds with less or even no side effects.Although substantial advances have been achieved in our understanding of the biology of opioid receptors,it is yet to find a solution to dwindling opioid side effects.Comparison studies have shown that existsing unpredictable action is due to the mutual structural and/or functional effect among the opioid receptors isoforms(i.e.,?/?/?/ORL-1 recptors).For instance,respiratory depression caused by the activation of ?-opioid receptor(MOR)could be eliminated by the activation of 8-opioid receptor(DOR).Meanwhile,the activation of K-opioid receptor(KOR)could against the euphoria and dependence originated from the MOR agonist effect.In addition,the activation of MOR could improve the convulsion due to the activation of DOR.Thus,the compounds with the ability to moderate activate multiple opioid receptors could reduced the potential side effect of opioid,which provids the new orientation for designing the multiple agonist of opioid receptor that with high analgesic and low side effect.BW373U86,one of diarylmethylpiperazine like compounds,is a small molecular receptor agonist which was the firstly designed by Prof.Kwen-jen Chang.Although have less analgesic effect,BW373U86 could against the respiratory depression and muscular anchylose caused by ? receptor agonist like Fentanyl.Based on the structure of BW373U86,we further optimize the configuration,and then get a array of ?/?/? receptor mixture agonists.Of these compounds,we found that DPI-3290 and DPI 125 had maximal high stimulation of ?&? receptor,and a little low stimulation of ? receptor.Both of them have high analgesia effect as well as low respiratory deression and low dependence.Because of these characters,we further designed the novel diarylmethylpiperazine derivations by allocation the proportion in activation ability of ?,?,? receptor and investigated effect of proportion in activation ability of ?,?,? receptor on the pharmacological response of compounds.Thses work will be contribute to tap the perfect compounds with ideal analgesia effect and low toxicity.thus the research works are carried out as follow:ObjectiveIn the present study,we investigated the action relationship between diarylmethylpiperazine derivations like kust102 and opioid receptors,and then evaluated the pharmacodynamics of kust102 on analgesia and the potential dependence and tolerance effect.Based on these data,we analysed the correlation between pharmacodynamics response and receptor agonist action,which provide the theoretic and empirical data for tapping the strong analgesic effect and low toxicity compounds.MethodStimulation effectivity was determined by use[35S]GTP ? S assays in CHO-?,CHO-?,CHO-8,and CHO-ORL1 stable transfected cell membranes and PKAcat-EGFP Redistribution Assay in CHO-?-PKAcat-GFP?CHO-?-PKAcat-GFP?CHO-?-PKAcat-GFP cell line.Then analgesic effects and tolerance were evaluate in the mouse/rat tail-flick test and the mouse 55? hot-plate test,and physical dependence and psychological dependence of kust102 was evaluate in the naloxone-precipitated withdrawal sign and conditioned place preference.Result1.Kust102 produced maximal stimulation of[35S]GTP?S binding on DOR-(112%),MOR(111%),KOR-(62.6%)opioid receptors and the EC50 values were 42.2 nM,129 nM,970 nM respectively.Theratio of EC50 of kust102 to DOR?MOR?KOR is 1:3.06:22.98.2.In the mouse hot-plate tests,the antinociceptive ED50 of kust102 was 3.8mg/kg(i.p.)similar with morphine's 3.4 mg/kg(s.c.).But kust102 have a long-lasting action which is about 5h,significantly higher than morphine(1.5h)3.Similar with morphine,chronic treatment of kust102 could result in dramatic development of tolerance.4.Mice repeatedly injected increasing doses of kust could produce a obvious naloxone-precipitated jumping symptoms same as morphine.Mice experiments further demonstrated that kust 102 lead to an significant conditioned place preference.ConclusionThe results in vivo and in vitro show that Kust102 is a Multi-subtype opioid receptors agonists with maximal high stimulation of ?&? receptor,weaker stimulation of ? receptor.Pharmacodynamics evaluation show that kust 102 have high antinociceptive effect and long-lasting action,low physical dependence but still have tolerance and psychical dependence.kust 102 is not the ideal analgesic with high-efficient and low-side effect,but these studies provides us with a practical evaluation system to further analyse the relationship between subtybe-opioid receptor and activity.