Effects of conventional antiepileptic drugs in a model of spontaneous recurrent seizures in rats (original) (raw)
Related papers
Epilepsia, 2009
Purpose: Pentylenetetrazole (PTZ) and maximal electroshock (MES) models are often used to induce seizures in nonepileptic control animals or naive animals. Despite being widely used to screen antiepileptic drugs (AEDs), both models have so far failed to detect potentially useful AEDs for treating drug-resistant epilepsies. Here we investigated whether the acute induction of MES and PTZ seizures in epileptic rats might yield a distinct screening profile for AEDs.Methods: Status epilepticus (SE) was induced in adult male Wistar rats by intraperitoneal pilocarpine injection (Pilo, 320 mg/kg, i.p.). One month later, controls or naive animals (Cont) that did not develop SE postpilocarpine (N-Epi) and pilocarpine-epileptic rats (Epi) received one of the following: phenobarbital (PB, 40 mg/kg), phenytoin (PHT, 50 mg/kg), or valproic acid (VPA, 400 mg/kg). Thirty min later the animals were challenged with either subcutaneous MES or PTZ (50 mg/kg, s.c.).Results: VPA, PB, and PHT were able to prevent MES in all groups tested (Cont, N-Epi, and Epi groups), whereas for the PTZ model, only the Cont group (naive animals) had seizure control with the same AEDs. In addition, Epi and N-Epi groups when challenged with PTZ exhibited a higher incidence of severe seizures (scores IV-IX) and SE (p < 0.05, Fisher's exact test).Conclusions: Our findings suggest that the induction of acute seizures with PTZ, but not with MES, in animals pretreated with pilocarpine (regardless of SE induction) might constitute an effective and valuable method to screen AEDs and to study mechanisms involved in pharmacoresistant temporal lobe epilepsy (TLE).
Experimental chronic epilepsy in rats: A screening method for antiepileptic drugs
Pharmacological Research Communications, 1983
Rats were rendered epileptic by subpial injection of an FeCI 3 solution. Epileptiform discharges, recorded by chronically implanted extradural electrodes, were evident within 48 h of surgery and persisted for more than 6 months. It is demonstrated that this model is useful for studying new antiepileptic agents since a series of clinically effective drugs (diazepa~, clonazepam, Na phenobarbital, primidone, carbamezepine, ethosuximide, diphenylhydantoin, Na valproate, GABOB) show an activity which is dose-dependent and within a range satisfactorily related to human dosages.
Spontaneous recurrent seizures in rats: An experimental model of partial epilepsy
Neuroscience & Biobehavioral Reviews, 1990
LEITE. J. P., Z. A. BORTOLOTTO AND E. A. CAVALHEIRO. Spontaneous recurrent seizures in rats: An e.rperimental model of partial epilepsy. NEUROSCI BIOBEHAV REV 14(4) 511-517. 1990.--Seizures induced by pilocarpine (PILO) have proven to be a useful procedure for investigating the basic mechanisms essential for generation, spread and motor expression of seizures in rodents. Here we report the long-term effects of PILO in rats. Following PILO (380 mg/kg, IP), 3 distinct phases were observed: 1) an acute period which lasted 1-2 days which corresponds to the pattern of repetitive seizures and status epilepticus: 2) a silent period (,'1 ,11 days) characterized by a progressive return to normal EEG and behavior: and 3) a period of recurrent seizures which started 5--15 days alter PILO and lasted up to 120 days. These seizures lasted up to 50-60 sec, recurred 2-3 times per week and were more frequent during the light period of the light-dark cycle. These serial events offer a new method to induce spontaneous recurrent seizures in rats.
Seizures and Antiepileptic Drugs: From Pathophysiology to Clinical Practice
Current pharmaceutical design, 2017
Recurrent, spontaneous seizure activity caused by abnormal neuronal firing in the brain is a hallmark of epilepsy, a common chronic neurological disorder. Recent research that has expanded the knowledge of the cellular and molecular mechanisms that modulate neuronal excitability and network activity in the brain provides the development and discovery of antiepileptic drugs (AEDs). AED therapy starts with the selection of the most appropriate drug for individual patient according to a strategic decision based on the risk-benefit ratio. Beyond three generations of AEDs developed over the last 40 years, more effective, better tolerated, disease-modifying pharmacological therapies are still needed to improve seizure outcome and reduce the safety burden. In this review, we aim to provide a special focus on epilepsy with an overview of underlying pathophysiological mechanisms that may contribute to seizure generation and propagation. Besides, knowledge of principle pharmacological propert...
The Pilocarpine Model of Seizures
Models of Seizures and Epilepsy, 2006
The systemic administration of a potent muscarinic agonist pilocarpine in rats promotes sequential behavioral and electrographic changes that can be divided into 3 distinct periods: (a) an acute period that built up progressively into a limbic status epilepticus and that lasts 24 h, (b) a silent period with a progressive normalization of EEG and behavior which varies from 4 to 44 days, and (c) a chronic period with spontaneous recurrent seizures (SRSs). The main features of the SRSs observed during the long-term period resemble those of human complex partial seizures and recurs 2-3 times per week per animal. Therefore, the pilocarpine model of epilepsy is a valuable tool not only to study the pathogenesis of temporal lobe epilepsy in human condition, but also to evaluate potential antiepileptogenic drugs. This review concentrates on data from pilocarpine model of epilepsy.
Difficulties in Treatment and Management of Epilepsy and Challenges in New Drug Development
Epilepsy is a serious neurological disorder that affects around 50 million people worldwide. Almost 30% of epileptic patients suffer from pharmacoresistance, which is associated with social isolation, dependent behaviour, low marriage rates, unemployment, psychological issues and reduced quality of life. Currently available antiepileptic drugs have a limited efficacy, and their negative properties limit their use and cause difficulties in patient management. Antiepileptic drugs can provide only symptomatic relief as these drugs suppress seizures but do not have ability to cure epileptogenesis. The long term use of antiepileptic drugs is limited due to their adverse effects, withdrawal symptoms, deleterious interactions with other drugs and economic burden, especially in developing countries. Furthermore, some of the available antiepileptic drugs may even potentiate certain type of seizures. Several in vivo and in vitro animal models have been proposed and many new antiepileptic drugs have been marketed recently, but large numbers of patients are still pharmacoresistant. This review will highlight the difficulties in treatment and management of epilepsy and the limitations of available antiepileptic drugs and animal seizure models.
MODELS OF EPILEPSY USED IN ANTIEPILEPTIC DRUG DISCOVERY: A REVIEW Review Article
International journal of Pharmacy and Pharmaceutical Sciences, 2014
This article describes various experimental models of seizure and epilepsy. Epilepsy is characterised by recurrent unprovoked seizures. Antiepileptic drug discovery in animal models starts with the assumption that the experimental seizure model mimics human seizure. Hence a drug which suppresses ictogenesis or inhibits epileptogenesis in animal model is a potential antiepileptic drug for human and it needs further investigation. Phenytoin and Carbamazepine were identified with the help of relatively simple models like Maximal electroshock seizure and the pentylenetetrazole test. Lots of drugs were discovered with the help of these models but a big portion of patients still remains resistant to the available antiepileptic drugs. Again these simple seizure models are increasingly being questioned, are they providing us same type of drugs with same kind of mechanism of action? This question brings the importance of newer animal models that target epileptogenesis, pharmacoresistant epilepsy and models which mimic human epilepsy more closely. There is increased concern on agents for epilepsy disease modification and prevention. To solve these unmet needs, the research scientist must have a thorough knowledge of available animal models of epilepsy so that he can pick up the best model for his research. In this article, we are reviewing the diversity of animal models of epilepsy and their implications in antiepileptic drug discovery.
Animal models for the development of new neuropharmacological therapeutics in the status epilepticus
Current neuropharmacology, 2006
Status epilepticus (SE) is a major medical emergency associated with significant morbidity and mortality. SE is best defined as a continuous, generalized, convulsive seizure lasting > 5 min, or two or more seizures during which the patient does not return to baseline consciousness. The relative efficacy and safety of different drugs in the treatment of human SE should be determined in a prospective, randomized, blinded study. However, complementary animal models of SE are required to answer important questions concerning the treatment of SE because of the obvious difficulties of setting up such studies in clinical emergency conditions. This review offers an overview of the implementation and characteristics of some of the most prevalent animal models of SE currently in use. A description is also provide about how animal models of SE may facilitate the use of neurobiological techniques to successfully address critical questions in the drug treatment of SE. In particular, the exper...
Anti-Epileptogenic Effects of Antiepileptic Drugs
International Journal of Molecular Sciences
Generally, the prevalence of epilepsy does not exceed 0.9% of the population and approximately 70% of epilepsy patients may be adequately controlled with antiepileptic drugs (AEDs). Moreover, status epilepticus (SE) or even a single seizure may produce neurodegeneration within the brain and SE has been recognized as one of acute brain insults leading to acquired epilepsy via the process of epileptogenesis. Two questions thus arise: (1) Are AEDs able to inhibit SE-induced neurodegeneration? and (2) if so, can a probable neuroprotective potential of particular AEDs stop epileptogenesis? An affirmative answer to the second question would practically point to the preventive potential of a given neuroprotective AED following acute brain insults. The available experimental data indicate that diazepam (at low and high doses), gabapentin, pregabalin, topiramate and valproate exhibited potent or moderate neuroprotective effects in diverse models of SE in rats. However, only diazepam (at high...