| QO-58, a new compound screened by Hebei Medical University, shows a good activity to enhance the potassium channel KCNQ2/3 currents in vitro experiments. KCNQ2/3 channel as a major composition of M currents is mainly distributed to nervous system. The channel can be activated near the threshold potential, and determining the excitability of neuron, that is to say, enhancing the channel activity maybe contribute to inhibiting the neuronal hyper-excitability. This function is needed to treat with the disease such as epilepsy, pain and other neurological and psychiatric disorders. Some chemical and electrical seizures animal models have been designed to illustrate whether the drug has the activity as an antiepileptic drug. Some experiments were explored to further more study its neurotoxicity, acute toxicity and analyze the impact on the brain neurotransmitter. The results above all maybe provide some important data for further pharmacological and toxicological tests.1 Anti-convulsion effect of epilepsy about QO-58Objective: To observed the effect of QO-58 on chemical and electrical seizures animal models test and analysis its antiepileptic function.Methods: (1) 180 KM mice, weight 18-22g, was divided into 6 groups randomly (n=30), all the animals was respectively administrated by p.o with QO-58 compounds, in low, medium and high three level dosage (12.5,25,50mg/kg), positive control compounds Retigabine, in small and large two level dosage (25,50mg/kg), solvent control group (DMAC: castor oil=1:9). The Anticonvulsant activity of QO-58 was evaluated in the maximal electroshock seizure model (MES) by calculating the negative-respond mice number or the protection rate, using YSD-4G physiological and pharmacological experiments multi-instrument (frequency: 50Hz, time: 0.25s, voltage 100V), after administration 12h. We determined. (2) 72 KM mice, weight 18-22g, were divided into 6 groups randomly, each group had the same number 12 animals. The plan of administration was the similar to the previous test. The metrazol maximal seizure model (MMS) was applied to observe the threshold of systemic clonic seizures, and record the negative-respond number in 30min, by injecting PTZ s.c. 85mg/kg on the back or neck in mice. (3) 4 SD rats, weight 180-220, were observed the changes of EEG pre and after injection PTZ which can be induced the seizure reaction, after administration of QO-58 50mg/kg 12 hours.Results: (1) Protection rate of mice in MES test, solvent group was 23.3%, QO-58 12.5,25, 50mg/kg three gruops were 33.3%, 50%, 73.3%. The medium and large dosage of QO-58 had significant differences with the solvent group (p<0.05, 0.01) and the positive control group (RTG) in small and large level were 80%, 83.3% and also were different significantly with the solvent group (p<0.01). (2) In MMS test, there was different responds between the solvent, QO-58 and RTG groups. The median of threshold that the animal generated convulsion symptoms were respectivly 456s, 559.5s, 697s (p<0.05), 979s (p<0.01), 1438s (p<0.05),1800s (p<0.01)respectively, and the rate of protection were 0%, 16.7%, 25%, 41.7% (p<0.05), 50% (p<0.01), 66.7% (p<0.01) respectively. (3) The EEG of rats had a significant changes pre and after injection PTZ. The typical spike waves were showed in epileptic seizure, the frequency of the waves was 20.20±2.15Hz and amplitude 1.26±0.17mV in solvent group, the frequency was 3.20±0.37Hz and amplitude 0.50±0.04 mV in QO-58 group.Conclusions: There were good effects of QO-58 after administation at the dose of 25 and 50mg/kg in the MES and MMS seizures test in mice. The 50mg/kg dosage of QO-58 can reduce the number of seizures'EEG effectively.2 Toxicity study about QO-58Objective: To observed the acute toxicity and other potential adverse ofQO-58 on cardiac, neuromuscular, and evaluate its safety. Methods: (1) Sixty KM mice, weight 18-22g, were divided into 5 groups randomly, each group had the same number 12 animals, including solvent gruop and QO-58 four groups 25,50,100,200mg/kg. The mice were placed in small animals fatigue machine to record the number dropped down after oral administration 12hours. (2) According to the simiar protocal of EEG, The rats ECG was recorded pre and after administration of QO-58 by BW-200 wireless telemetry system.changes (3) Ninty SD rats, weight 160-200, were divided into 15 groups randomly and each group had the same number 6 animals. Oral administration groups were 0.25, 0.5, 1.0, 2.0g/kg of the QO-58. Intramuscular injection groups were 3.75, 7.5, 15, 30mg/kg of the QO-58. Intravenous injection groups were 7.5, 15, 30, 60mg/kg of the QO-58. The acute toxicity of QO-58 was exposed to some extent by three ways of administration.Results: (1) In the rotarod test, the positive rate index which was calculated by the number of animals falling down from the fatigue machine showed as follow: 25,50,100,200mg/kg group of QO-58 was respectively 8.3%, 25%, 16.7%, 25%, compared with the group of solvent (positive rate was 8.3%) there were not significantly different. (2) There were no abnormal waveforms and no significant difference in the electrocardiogram after five days administration of QO-58. The parameter of RR, PR, QT didn't change significantly pre and after administration. (3) Oral administration of QO-58 in rats: NOAEL (No observed adverse effect Level ) is 0.5~1.0g/kg and MTD (the maximum tolerated dose) is greater than 2g/kg. Intramuscular injection of QO-58 in rats: NOAEL is 15~30mg/kg and MTD is greater than 30mg/kg. Intravenous QO-58 in rats: NOAEL is 15~30mg/kg, MLD (the minimum lethal dose) is 30~60mg/kg.Conclusions: There was no obvious toxicity on nervous-muscle system at the eight times of normal dosage and no obvious toxicity on cardiovascular system under the condition of continouslly 5days- administration in rats. The main advers of QO-58 is the central inhibition, and the dosage of NOAEL is the 20-40 times of the valid dose in pharmacodynamic test. 3 The effect of QO-58 on cerebral neurotransmittersObjective:To research of QO-58 on the level of Glu and GABA in brain and further illustrate the other possible mechanism.Methods: Eighteen SD rat, weight 180-220, were divided into 3 groups randomly, and each group had 6 animals. Each group 25 and 50 mg/kg of the QO-58 and solvent was administrated continuously 3days. The rats were implanted of microdialysis probe location in the hippocampus (AP=-5.8, R=5, H=-3) before the operation, then dialysed the cerebrospinal fluid and detected the concentration of Glu and GABA by HPLC, useing of microdialysis technique. After the fifth day of surgery operation and after three days of oral administration, we conducted microdialysis experiments respectively.Results: There were good peak shapes in separation of Glu and GABA in dialysate and good linear relationship in the concentration fllow as Glu 200~20μmol/L, GABA 100~10μmol/L. The standard curve were Y = 0.5371X-0.0512;Y=1.0039X-0.0912, r>0.99. The intra- and inter-day relative standard deviations (RSD) in the measurement of quality control (QC) samples were less than 15%. quality control (QC) samples at room temperature 2h, 4℃placed a week, 3 times freeze-thaw cycles were stable, the Relative error (RE) were within±10%, RSD <15%. Glu release in the hippocampus was no significant difference before and after giving of the QO-58. QO-58 in the two dose groups (25mg/kg, 50mg/kg) could significantly increase the GABA release (p<0.01, p<0.01).Conclusions: QO-58 can significantly increase the release of GABA in hippocampus.SummaryQO-58 had good antiepileptic effects in electric and PTZ-induced seizures models at the level of 25 and 50mg/kg dosage, could reduce the number of seizures'EEG and inhibit abnormal discharge of neurons effectively. There were no obvious toxicity on cardiovascular system and nervous system. The acute toxicity test showed that the main advers of QO-58 is the central inhibition, and the dosage of NOAEL is the 20-40 times of the valid dose in pharmacodynamic experiments. QO-58 can significantly increase the release of GABA in hippocampus and have no effect on Glu. |
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