The Effect And Mechanisms Of Tanshinone ⅡA In Improving Cognitive Deficits Induced By Status Epilepticus

Background : Epilepsy is one of the most common nervous system diseases in clinic.Seizures are also common in neurodevelopmental disorders such as fragile X syndrome(FXS).The occurrence and development of epilepsy may lead to structural changes and functional impairment of related neural circuits,such as spatial memory disorder,learning disorder,social disorder,anxiety and aggressive behavior.However,there is still a lack of drugs that can not only prevent epilepsy but also protect the cognitive impairment of epileptics.Tanshinone Ⅱa has shown anti-inflammatory,antitumor and anti-oxidation effects,but it is not clear whether Tanshinone Ⅱa can be used to improve cognitive impairment caused by epilepsy.Objective: To investigate the effects of Tanshinone Ⅱa on cognitive deficits induced by status seizures and the effects of audiogenic seizure on cognitive behavior in FXS model mice.Methods: 1)Sixty male C57BL/6 mice(18-22g)were randomly divided into two groups: control group and model group,and each group is divided into Tanshinone Ⅱa treatment and saline group.Morris mater maze experiment was used to detect the learning and memory ability,the open maze experiment was used to detect the depression behaviors,and the elevated plus maze was used to detect the anxiety. The long term potentiation(LTP)and long term depression(LTD)in the hippocampal CA1 region were recorded and analyzed by using the microelectrode matrix technique(MED64)to identify the effects of Tanshinone Ⅱa on synaptic transmission.QPCR was used to detect hippocampal mRNA levels of RyR1-3,CaMKII,etc.Western blot was used to detect the protein expression level of RyR2 and CAMKII in the hippocampus.Further to uncover molecular mechanisms that Tanshinone Ⅱa in correcting cognitive dysfunction induced by epilepsy in mice.2)Thirty adult WT and thirty Fmr1 KO male mice were randomly divided into two groups respectively,including WT blank control group and WT audiogenic seizure group,Fmr1 KO blank control group,Fmr1 KO audiogenic seizure group. The above behavioral tests and electrophysiological recording were used to detect the effects of epileptic on cognition in FXS model mice.Results: 1)Tanshinone Ⅱa had protective effects against seizure induced by PTZ in mice.2)Mice with chronic epileptic induced by PTZ showed obvious decline in learning ability and spatial memory in Morris water maze test,which improved by Tanshinone Ⅱa but not saline.3)Mice with chronic epileptic induced by PTZ showed anxiety disorder in the open maze and the elevated plus maze,which was corrected by Tanshinone Ⅱa.4)The level of RyR2 mRNA in hippocampus increased significantly induced by PTZ (p < 0.05)but corrected by Tanshinone Ⅱa treatment.5)The expressions of CaMKⅡ and RyR2 in hippocampus tissue were corrected by Tanshinone Ⅱa treatment.6)Tanshinone Ⅱa protected the hippocampus synaptic plasticity against damage by PTZ by correcting LTP & LTD dysfunction in hippocampal CA1 area.7)The latency of auditory seizures in Fmr1 KO mice was significantly shorter than WT,and Fmr1 KO mice were sensitive to high-frequency acoustic stimuli.8)The Fmr1 KO mice showed obvious decline in learning ability and spatial memory in Morris water maze test.The audiogenic seizure induced damage in spatial memory was not significant in Fmr1 KO mice,but visible in WT.9)In the open maze and the elevated plus maze,Fmr1 KO mice induced by audiogenic seizure showed abnormally exploratory behavior and anxiety disorder,but the WT mice kept normal.10)In the electrophysiological experiment,both Fmr1 KO mice and WT mice showed hippocampal synaptic plasticity damage with acoustic stimuli.The WT mice showed LTP & LTD dysfunction in hippocampal CA1 area induced by the audiogenic seizure,and Fmr1 KO mice showed LTP inhibit but normal LTD induced by the audiogenic seizure.Conclusions: 1)The PTZ induces chronic epilepsy in mice,and TⅡA significantly improves the cognition performance and corrects brain synaptic plasticity in mice with chronic epilepsy induced by PTZ,the mechanisms would involve in regulating the RyR2 mRNA transcription and RyR2 protein synthesis and phosphorylation.2)The audiogenic seizure induce spatial memory damage in WT mice,but result in inhibited exploratory behavior and increased anxiety disorder in Fmr1 KO mice, as well as induce hippocampus synaptic plasticity damage in both Fmr1 KO mice and WT mice.