动物造模,药效评价,慢性癫痫 z-bio 2024-08-02 419

　　The chronic epilepsy model can reflect the initiation, development, and accompanying pathological and physiological changes in the brain during epileptic seizures. This provides a foundation for further research on epilepsy. According to the intensity of the stimulus given and the severity of the condition induced, it can be divided into three models: ignition model, persistent epilepsy model, and spontaneous epilepsy model.

　　（1） Ignite the model

　　The ignition model refers to the repeated stimulation of the thalamus and hippocampus with initial sub convulsive doses (electrical/chemical drug stimulation), gradually lowering the seizure threshold and increasing sensitivity, undergoing a chronic process from partial seizures (grades 1-3) to systemic seizures (grades 4-5), ultimately resulting in recurrent and spontaneous seizures.

　　Modeling methods and model characteristics

　　The electrical stimulation ignition model is the most commonly used complex partial model for studying the mechanism of epilepsy. Whether ignition can occur depends on parameters such as stimulation duration, intensity, and stimulation interval time. The standard stimulation conditions are a current intensity of 3mA, lasting for 2 seconds, once a day (in mice); 8mA, lasting for 4 seconds, twice a day (in rats), until a level 5 attack occurs, it is considered to have reached complete ignition. Select rats with 10 consecutive episodes reaching level 5 for screening antiepileptic drugs and studying their mechanisms. The ignition process can be divided into six stages: ① ipsilateral facial twitching; ② Facial twitching on both sides; ③ Nodding; ④ The contralateral forelimb experiences spasms; ⑤ Standing with spasmodic jumping; ⑥ Falling accompanied by a generalized tonic spasm. Electrical stimulation of many parts of the brain can cause ignition, with the amygdala being the most easily ignited area, followed by the neocortex and hippocampus.

　　2. Chemical ignition model - Coriaria lactone ignition model Coriaria lactone 1.25-1.75mg/kg intramuscular or intraperitoneal injection, once/84 hours, with an average of 15 times (7-20 times). After the 8th administration, the animals showed staring, rapid breathing, and dilation of the external ear veins, which later developed into motor incoordination, facial twitching, whisker shaking, and forelimb twitching (with attack levels of 1-3), accompanied by spine waves and multiple spine waves. Completely ignited rats exhibit standing with upper limb twitching (level 4) and loss of balance and falling (level 5), ultimately presenting as generalized tonic clonic seizures lasting 10-20 seconds, with high amplitude epileptic discharges on electroencephalography (EEG). The pathological changes in this model mainly include significant degeneration and necrosis of astrocytes in the hippocampus, indicating that magnolol has a damaging effect on astrocytes and cortical cells, which may play a role in inducing epileptic seizures. This model is easy to establish, has high ignition efficiency, low mortality rate, and is suitable for promotion.

　　Model evaluation and application: Ignite model behavior norms, with good controllability and repeatability, easy to judge and quantitatively study. This provides an ideal animal model for studying the mechanisms of human epilepsy, drug efficacy, and the molecular mechanisms of antiepileptic drug resistance, in order to search for new or more effective therapeutic drugs. This model simulates the entire process of human epilepsy occurrence, spread, and formation well, and is therefore considered a chronic model that is closer to human epilepsy. The ignition model is widely used to search for new drugs to treat partial seizures. During the ignition process, the tested drug is given in advance to observe whether it can prevent or delay the occurrence of ignition phenomenon, in order to detect whether the drug has anticonvulsant and/or antiepileptic effects on the formation of epileptic foci.

　　（2） Persistent epilepsy model and spontaneous epilepsy model

　　1. Lithium Pilocarpine model

　　The Lithium Pilocarpine model is currently the most widely used model for status epilepticus and spontaneous seizures. Pilocarpine is a cholinergic muscle agonist that can cause seizures when administered systemically. Lithium chloride is used to increase the body's sensitivity to pilocarpine.

　　【 Modeling Method and Characteristics 】 Lithium 125mg/kg was intraperitoneally injected, followed by pilocarpine 30mg/kg intraperitoneally injected 18-24 hours later. Inject 1mg/kg of scopolamine intraperitoneally 30 minutes before administering pilocarpine to alleviate peripheral symptoms. Its occurrence and development process can be divided into acute phase, quiescent phase, and chronic phase. Acute phase: manifested as status epilepticus lasting for 24 hours. The level of convulsive behavior response is classified according to the Racine grading system. Static period: complete cessation of seizures, restoration of normal eating and activity, weight gain, partial irritability, and aggressive behavior; EEG is normal; Lasts for 4 to 44 days. Chronic phase: Repeated spontaneous epileptic seizures occur, equivalent to levels 4-5 of the ignition model, lasting for several seconds to tens of seconds, 2-3 times per week. The Lithium Pilocarpine model is highly correlated with age. After induction in adult mice, spontaneous epileptic seizures can occur 100% with a latency period of (15 ± 3) days. Neuronal damage is mainly located in the hippocampus, thalamus, piriform nucleus, and neocortex; After inducing SE in 18-24 day old rats, 22% of them exhibited spontaneous epileptic seizures with a latency period of (37 ± 25) days. The neuropathological changes were the same as those in adult rats. After induction in 7-11 day old rats, there were no spontaneous epileptic seizures or neurological damage.

　　[Model Evaluation and Application] Refer to the Hairen Acid Model.

　　2. Hairen Acid Model

　　【 Modeling mechanism 】 Kainic acid (KA) has a structure similar to glutamate and can produce strong neural excitatory effects. KA binds to the kainic acid receptor on the postsynaptic membrane, generating excitatory postsynaptic potentials and causing epileptic seizures.

　　【 Modeling Method and Characteristics 】 Whole body administration (intravenous or intraperitoneal injection), KA 4mg/kg; local administration (intraventricular, unilateral or bilateral hippocampus, amygdala, piriform nucleus, striatum, etc.) 0.1-2.0 μ g. According to the symptoms, it can be divided into acute phase (4-7 days after injection), quiescent phase (4-7 days after acute phase), and chronic phase. Acute phase (status epilepticus): After injecting KA for a few minutes, there will be tremors, facial muscle twitching, and tail lifting, followed by staring, nodding, chewing, and shaking of both upper limbs. Eventually, it will develop into contralateral rolling and whole body rigidity, lasting for 3-5 hours. Static period: The attack completely stops, normal eating and activity are restored, weight is restored, and some rats are prone to irritability and aggressive behavior. Chronic phase (spontaneous seizures): Spontaneous recurrent epileptic seizures are the main characteristic of this period. The seizure is similar to an amygdala ignition seizure, lasting 40-60 seconds, characterized by drooling, chewing, spasms in both upper limbs, wet dog like shaking, standing, losing balance and falling.

　　【 Model Evaluation and Application 】 The occurrence and development process of Lithium Pilocarpine and KA models is highly similar to that of human temporal lobe epilepsy, with the same pathological basis (neuronal loss, glial cell proliferation, mossy fiber filamentous sprouting, etc.). They are resistant to most antiepileptic drugs and have been widely used in the study of antiepileptic drug resistance mechanisms and molecular mechanisms of epilepsy occurrence.