Experimental Models of Status Epilepticus and Neuronal Injury for Evaluation of Therapeutic Interventions

This article describes current experimental models of status epilepticus (SE) and neuronal injury for use in the screening of new therapeutic agents. Epilepsy is a common neurological disorder characterized by recurrent unprovoked seizures. SE is an emergency condition associated with continuous seizures lasting more than 30 min. It causes significant mortality and morbidity. SE can cause devastating damage to the brain leading to cognitive impairment and increased risk of epilepsy. Benzodiazepines are the first-line drugs for the treatment of SE, however, many people exhibit partial or complete resistance due to a breakdown of GABA inhibition. Therefore, new drugs with neuroprotective effects against the SE-induced neuronal injury and degeneration are desirable. Animal models are used to study the pathophysiology of SE and for the discovery of newer anticonvulsants. In SE paradigms, seizures are induced in rodents by chemical agents or by electrical stimulation of brain structures. Electrical stimulation includes perforant path and self-sustaining stimulation models. Pharmacological models include kainic acid, pilocarpine, flurothyl, organophosphates and other convulsants that induce SE in rodents. Neuronal injury occurs within the initial SE episode, and animals exhibit cognitive dysfunction and spontaneous seizures several weeks after this precipitating event. Current SE models have potential applications but have some limitations. In general, the experimental SE model should be analogous to the human seizure state and it should share very similar neuropathological mechanisms. The pilocarpine and diisopropylfluorophosphate models are associated with prolonged, diazepam-insensitive seizures and neurodegeneration and therefore represent paradigms of refractory SE. Novel mechanism-based or clinically relevant models are essential to identify new therapies for SE and neuroprotective interventions

Atomic Force Microscopy Protocol for Measurement of Membrane Plasticity and Extracellular Interactions in Single Neurons in Epilepsy

Physiological interactions between extracellular matrix (ECM) proteins and membrane integrin receptors play a crucial role in neuroplasticity in the hippocampus, a key region involved in epilepsy. The atomic force microscopy (AFM) is a cutting-edge technique to study structural and functional measurements at nanometer resolution between the AFM probe and cell surface under liquid. AFM has been incrementally employed in living cells including the nervous system. AFM is a unique technique that directly measures functional information at a nanoscale resolution. In addition to its ability to acquire detailed 3D imaging, the AFM probe permits quantitative measurements on the structure and function of the intracellular components such as cytoskeleton, adhesion force and binding probability between membrane receptors and ligands coated in the AFM probe, as well as the cell stiffness. Here we describe an optimized AFM protocol and its application for analysis of membrane plasticity and mechanical dynamics of individual hippocampus neurons in mice with chronic epilepsy. The unbinding force and binding probability between ECM, fibronectin-coated AFM probe and membrane integrin were strikingly lower in dentate gyrus granule cells in epilepsy. Cell elasticity, which represents changes in cytoskeletal reorganization, was significantly increased in epilepsy. The fibronectin-integrin binding probability was prevented by anti-α5β1 integrin. Thus, AFM is a unique nanotechnique that allows progressive functional changes in neuronal membrane plasticity and mechanotransduction in epilepsy and related brain disorders

Method of treating organophosphate intoxication by administration of neurosteroids

The present invention provides new compositions and methods for treating and/or reversing organophosphate intoxication, manifested by both cholinergic and non-cholinergic crisis, in a mammal resulting from exposure to organophosphate compounds. The neurosteroidal compounds of this invention are those having the general structural formula of pregnane, androstane, 19-norandrostanes, and norpregnane with further moieties as defined herein. These compounds include, but are not limited to, ganaxolone, pregnanolone, and androstanediol and their analogs, salts and prodrugs. The present invention further relates to combining a therapeutically effective amount of a neurosteroidal compound with a standard organophosphate antidote (e.g. atropine, pralidoxime). The data suggests that neurosteroids are effective or more effective than benzodiazepines, whether given earlier or later than 40-min (up to several hours) after organophosphate compound exposure. Neurosteroids are effective to attenuate long-term neuropsychiatric deficits caused by organophosphate exposure.U

Method of treating organophosphate intoxication by administration of neurosteroids

The present invention provides new compositions and methods for treating and/or reversing organophosphate intoxication, manifested by both cholinergic and non-cholinergic crisis, in a mammal resulting from exposure to organophosphate compounds. The neurosteroidal compounds of this invention are those having the general structural formula of pregnane, androstane, 19-norandrostanes, and norpregnane with further moieties as defined herein. These compounds include, but are not limited to, ganaxolone, pregnanolone, and androstanediol and their analogs, salts and prodrugs. The present invention further relates to combining a therapeutically effective amount of a neurosteroidal compound with a standard organophosphate antidote (e.g. atropine, pralidoxime). The data suggests that neurosteroids are effective or more effective than benzodiazepines, whether given earlier or later than 40-min (up to several hours) after organophosphate compound exposure. Neurosteroids are effective to attenuate long-term neuropsychiatric deficits caused by organophosphate exposure.U

Clinical pharmacokinetic interactions between antiepileptic drugs and hormonal contraceptives

vii, 36 hl

Catamenial Epilepsy: Discovery of an Extrasynaptic Molecular Mechanism for Targeted Therapy

Catamenial epilepsy is a complex neuroendocrine condition in which seizures are clustered around specific points in the menstrual cycle, most often around perimenstrual or periovulatory period. The pathophysiology of catamenial epilepsy still remains unclear, yet there are few animal models to study this gender-specific disorder. The pathophysiology of perimenstrual catamenial epilepsy involves the withdrawal of the progesterone-derived GABA-A receptor modulating neurosteroids as a result of the fall in progesterone at the time of menstruation. These manifestations can be faithfully reproduced in rodents by specific neuroendocrine manipulations. Because mice and rats, like humans, have ovarian cycles with circulating hormones, they appear to be suitable animal models for studies of perimenstrual seizures. Recently, we created specific experimental models to mimic perimenstrual seizures. Studies in rat and mouse models of catamenial epilepsy show enhanced susceptibility to seizures or increased seizure exacerbations following neurosteroid withdrawal. During such a seizure exacerbation period, there is a marked reduction in the antiseizure potency of commonly prescribed antiepileptics, such as benzodiazepines, but an increase in the anticonvulsant potency of exogenous neurosteroids. We discovered an extrasynaptic molecular mechanism of catamenial epilepsy. In essence, extrasynaptic delta-GABA-A receptors are upregulated during perimenstrual-like neuroendocrine milieu. Consequently, there is enhanced antiseizure efficacy of neurosteroids in catamenial models because delta-GABA-A receptors confer neurosteroid sensitivity and greater seizure protection. Molecular mechanisms such as these offer a strong rationale for the clinical development of a neurosteroid replacement therapy for catamenial epilepsy

Neurosteroid Compounds And Methods For Their Preparation And Use In Treating Central Nervous System Disorders

Described herein is the chemical structure of neurosteroid derivative compounds, methods of synthesizing the derivatives, and their uses in treating disorders, including those of the central nervous system. These compounds are readily synthesized and have improved pharmaceutical properties, including water solubility, compared to known neurosteroids.U

Method of treating organophosphate intoxication by administration of neurosteroids

The present invention provides new compositions and methods for treating and/or reversing organophosphate intoxication, manifested by both cholinergic and non-cholinergic crisis, in a mammal resulting from exposure to organophosphate compounds. The neurosteroidal compounds of this invention are those having the general structural formula of pregnane, androstane, 19-norandrostanes, and norpregnane with further moieties as defined herein. These compounds include, but are not limited to, ganaxolone, pregnanolone, and androstanediol and their analogs, salts and prodrugs. The present invention further relates to combining a therapeutically effective amount of a neurosteroidal compound with a standard organophosphate antidote (e.g. atropine, pralidoxime). The data suggests that neurosteroids are effective or more effective than benzodiazepines, whether given earlier or later than 40-min (up to several hours) after organophosphate compound exposure. Neurosteroids are effective to attenuate long-term neuropsychiatric deficits caused by organophosphate exposure.U