The Anticonvulsive Effects Of Cantharidin Derivatives And Influence On GABA,GABA_B Receptor

Objective To compare the anti-maximal electroshock seizure(MES) effects of 10 different kinds of cantharidin derivatives, and screen the highly effective compound. To study anti-convulsion effects, toxicity and pharmacodynamic parameters of 4- amine 2- methoxy can-tharidin(AMOC). Establish the electrical stimulation of sciatic nerve and penicilin(PNC) co-ordination inducing convulsion model in rat,observe the influence of AMOC to convulsion rat's cerebral cortex electroencephalogram (EcoG), evoked potential (CEP) and the contents ofγ- aminobutyric acid (GABA) and GABAB receptor in order to discuss the anticonvulsion mecha-nism of AMOC.Methods (1)Established MES model in mice, determined anti-maximal electroshock seizure effect of 10 different kinds of cantharidin derivatives; take carbamazepine (CBZ), topiramate(TPM) as positive control, analysis the dose-effect and the time-effect relationship of different dosage AMOC in intragastrical (ig) mice, calculated ED50 of anti-MES according to the Bliss's method, compared its potency and efficacy; Metrazol seizure test(MET) to compare the convulsion seizure latency, anti- convulsion rate of AMOC,CBZ and TPM;The roll club method was adopted to analysis the toxic effect of intragastrical (ig) AMOC,CBZ and TPM, according to the Bliss's method to calculated TD50, compared toxic effects of different medicines;(2) Pharmacodynamic parameters of AMOC, CBZ, TPM were assayed by means of Pharmacologi-cal Effective Method. (3) Used electricity stimulating sciatic nerve and penicillin(PNC) coordi-nation induces rat convulsion model, Valproate(VPA) as the positive control, the convulsion sei-zure latency and Racine behavior study graduation as index to evaluate drug efficacy, RM6240C multi-channel biology signal gathered processing system synchronization record EcoG and CEP of convulsion rats, after intragastric AMOC (0.044g?kg-1 , 0.175?kg-1) , analyze the anti-convulsion effects and influence on the epileptiform discharge laten period, frequency, the highest amplitude and CEP amplitude; (4) The content of GABA and GABAB receptor in brain cortex and hippocampus area in convulsion rats was determinated by immunohistochemistry technology.Results (1) The antagonize MES effects of AMOC and AMC is the strongest among 10 differ-ent kinds of cantharidin derivatives, both anti-convulsion rate is 100%.(2) AMOC, CBZ and TPM could dose-dependently antagonize MES in mice, anti-convulsion rate are respectively AMOC 100%, CBZ 100%,TPM 90%; The ED50 are AMOC(0.0529 g?kg-1), TPM (0.22 g?kg-1), CBZ(0.016 g?kg-1); (3) AMOC, CBZ and TPM could prolong the MET convulsion seizure latency, The latency value were respectively AMOC (13.7±5.68min),TPM (9.57±4.47min), CBZ (9.51±2.52 min), compare with the control group have the significance difference(P<0.01); (4) AMOC, CBZ and TPM have CNS toxic effect, TD50 are respectively AMOC(0.611g?kg-1),TPM(0.492g?kg-1),CBZ(0.141g?kg-1);(5) The results of pharmaco-dynamic parameters indicated the minimum effect dosage of different medicines from low to high were were CBZ, AMOC, TPM; The peak time of AMOC and CBZ were 12 min, TPM were 2h: The t1/2 (ED) of AMOC, CBZ and TPM were respectively 2.8h,2.7h and 2.6h,the persist time all were 12h; Elimination Constant of AMOC were smaller than other two medicines. (6) Influence of AMOC on epileptiform behavior in pencillin-induced seizure rats: AMOC and VPA could inhibit epileptiform behavior, and prolong the seizure latency obviously, compare with the PNC group has the significance difference(P<0.01). (7) The influence of AMOC on EcoG and CEP with seizure rats: 30min after intragastricing two dosage AMOC and VPA, could prolong the epileptiform discharge laten period (6.13±0.51min), reduce the frequency of epileptiform discharge ( 33.17±8.80 min-1), lower the highest wave amplitude(1.22±0.26mV) and the evoked potential amplitude, compares with the PNC group has the significance difference(P<0.01). (8) The influence of AMOC on GABA and GABAB acceptor in brain of seizure rats: cerebral cortex spot: GABA expression quantity of great dosage AMOC and VPA were respectively 151601.2±23466.5, 117654.3±25305.1,higher than the normal group (88129.1±17370.3) and the model group (86352.6±12370.0), the GABAB receptor protein expression quantity also obviously ad-vances, and has statistics significance(P<0.05); Small, great dosage AMOC could increace the GABA content and GABAB receptor protein expression quantity,and were higher than the nor-mal group and the model group,but doesn't have statistics significance(P>0.05). Hippocampus spot: GABA expression quantity of great, small dosage AMOC and VPA were higher than the normal group and the model group in the value, but does not have statistics significance(P >0.05). Great, small dosage AMOC and the VPA could increace the GABAB acceptor protein expression quantity, separately compare with the normal control group and the model control group, has sta-tistics significance(P<0.05).Conclusions (1)The anti-MES effects of AMOC and AMC is the strongest among 10 different kinds of cantharidin derivatives, which is worth doing further experimental study. The anti-convulsion potency of AMOC is stronger than topiramate, similar with carbamazepine, the titre intensity is bigger than topiramate and smaller than carbamazepine; (2) AMOC could an-tagonize MET seizure,and was the strongest one compare with CBZ and TPM; (3) AOMC,CBZ and TPM have the CNS toxicity, and the TC50 value of AMOC is the biggest, explained that its toxicity is the smallest, the carbamazepine's TC50 value is smallest, explained that its toxicity is the biggest. (4) Pharmacodynamic parameters of AMC compare with CBZ and TPM, reaches the peak time quicker, t1/2 (ED) and the persist time is similar with CBZ and TPM, and eliminates slowlyer. (5) AMOC could antagonize the electricity stimulation sciatic nerve and the penicillin coordination inducing the rat convulsion seizure, reduce the frequency of epileptiform discharge , the highest wave amplitude and the evoked potential amplitude. (6) AMOC can raise cerebral cortex's GABA content, simultaneously enhances the content of GABAB receptor expression in cerebral cortex and the hippocampus area, this is possibly the anti-epilepsy action mechanism of AMOC.