The effect of GABA ergic system in the brain in mediating convulsions induced by quinolinic acid (QA) was studied. Muscimol,an agonist of GABAA-receptor, and aminooxyacetic acid (AOAA),an inhibitor of GABA transami-nase(GABA-T) ,and alprazolam which increased the affinity of GABA-receptor as it binds with benzodiazepine-receptor, were used to increase GABAergic function in the brain. Results showed that the above substances antagonized QA-induced convulsions. In contrast, bicu-culline,an antagonist of GABAA-receptor, and 3-mercaptopropionic acid (3-MP), an inhibitor of both GABA synthesis and its release, were used to decrease GABA ergic function in the CNS. They were found to potentiate QA-induced seizures. All these results suggest that GABA ergic system in brain plays an important role in modulating QA-induced convulsions.

Objective To observe the change of learning and memory and the expression change of GABAR1 and N-methyl-D-aspartate receptor 2B (NMDAR2B)in right frontal lobe of the brain of the aged rats after the inhalation of sevoflurane.Methods Fifty male SD rats were randomly divided into control group (group C,n=10)and experimental group (group T,n=40).The control group received air at room tempreture.Experimental groups were divided into two groups:group T1 (2 h)and group T2 (4 h)according to the time of inhalation of sevoflurane at 3% concentration.Ev-ery group was equally divided into two groups and Morris water maze was performed on day 1 and day 7 after sevoflurane inhalation.Then the right frontal lobe was gathered and the mRNA transcription and protein expression of GABAR1 and NMDAR2B were detected by Quantitative Real-time PCR and immunofluorescence technique.Results Compared with group C,the escape latency was prolonged in groups T1 and T2 after 1 day of inhalation of sevoflurane (P<0.05),and the times of space explora-tion reduced (P<0.05).mRNA transcriptional and protein content of GABAR1 were significantly upregulated in frontal lobes of groups T1 and T2,mRNA transcriptional and protein content of NMDAR2B were significantly down-regulated (P<0.05).After inhalation of sevoflurane for 7 days, the protein expression of NMDAR2B in the frontal lobe of group T1 was lower than that of group C (P<0.05).In group T2,the escape latency was prolonged (P<0.05),the number of space explo-ration traversals was decreased (P<0.05),the expression of GABAR1 protein in frontal lobe was up-regulated (P<0.05),and the expression of NMDAR2B protein was down-regulated (P<0.05), and the amplitude was higher than that in group T1 (P<0.05).Conclusion Continuous inhalation of sevoflurane can reduce the spatial memory ability of aged rats,and the effect of prolonged inhalation is greater and longer.This effect is related to the expression of neurotransmitter receptors such as GABAR1 and NMDAR2B in the frontal lobe.

Abnormally activated CDK9 participates in the super-enhancer mediated transcription of short-lived proteins required for cancer cell survival. Targeting CDK9 has shown potent anti-tumor activity in clinical trials among different cancers. However, the study and knowledge on drug resistance to CDK9 inhibitors are very limited. In this study, we established an AML cell line with acquired resistance to a highly selective CDK9 inhibitor BAY1251152. Through genomic sequencing, we identified in the kinase domain of CDK9 a mutation L156F, which is also a coding SNP in the CDK9 gene. By knocking in L156F into cancer cells using CRISPR/Cas9, we found that single CDK9 L156F could drive the resistance to CDK9 inhibitors, not only ATP competitive inhibitor but also PROTAC degrader. Mechanistically, CDK9 L156F disrupts the binding with inhibitors due to steric hindrance, further, the mutation affects the thermal stability and catalytic activity of CDK9 protein. To overcome the drug resistance mediated by the CDK9-L156F mutation, we discovered a compound, IHMT-CDK9-36 which showed potent inhibition activity both for CDK9 WT and L156F mutant. Together, we report a novel resistance mechanism for CDK9 inhibitors and provide a novel chemical scaffold for the future development of CDK9 inhibitors.

Angiogenesis is an essential process in tumor growth, invasion and metastasis. VEGF receptor 2 (VEGFR2) inhibitors targeting tumor angiogenic pathway have been widely used in the clinical cancer treatment. However, most of currently used VEGFR2 kinase inhibitors are multi-target inhibitors which might result in target-associated side effects and therefore limited clinical toleration. Highly selective VEGFR inhibitors are still highly demanded from both basic research and clinical application point of view. Here we report the discovery and characterization of a novel VEGFR2 inhibitor (CHMFL-VEGFR2-002), which exhibited high selectivity among structurally closed kinases including PDGFRs, FGFRs, CSF1R, etc. CHMFL-VEGFR2-002 displayed potent inhibitory activity against VEGFR2 kinase in the biochemical assay (IC = 66 nmol/L) and VEGFR2 autophosphorylation in cells (ECs ∼100 nmol/L) as well as potent anti-proliferation effect against VEGFR2 transformed BaF3 cells (GI = 150 nmol/L). In addition, CHMFL-VEGFR2-002 also displayed good anti-angiogenesis efficacy and exhibited good PK (pharmacokinetics) profile with bioavailability over 49% and anti-angiogenesis efficacy in both zebrafish and mouse models without apparent toxicity. These results suggest that CHMFL-VEGFR2-002 might be a useful research tool for dissecting new functions of VEGFR2 kinase as well as a potential anti-angiogenetic agent for the cancer therapy.