Introduction Epilepsy is a serious global problem that affects approximately 1% of people worldwide (1). Epilepsy is a chronic condition of the central nervous system (CNS) characterized by epileptic seizures, which can affect physical and mental functions (2). Epileptic seizures are unprovoked reoccurring episodes of abnormal, excessive, or hypersynchronis neuronal activity in the CNS (2). The treatment options of epilepsy include medications called antiepileptic drugs (AED) and surgeries based on individuals’ specific diagnosis and background (1). The AED Keppra®, S-enantiomer of α-ethyl-2-oxo-1-pyrrolidine acetamide, or Levetiracetam (LEV) is Food and Drug Administration (FDA)-approved for the treatment and prevention of epileptic seizures (3). However, the exact mechanism of action of Levetiracetam (LEV) is not currently understood and the anticonvulsant characteristics of LEV are different than other antiepileptic drugs (AEDs) (2). For instance, LEV does not present the ability to inhibit sodium channels or enhance g-aminobutyric acid (GABA) function like several other AEDs (1). The understanding of the mechanism of action of LEV as an AED is important to understand the cellular mechanisms and pathogenesis of epilepsy and develop new methods of treating epilepsy. Past studies have shown LEV to target high-voltage-activated (HVA) N-type calcium (Ca2+) channels, the synaptic vesicle protein 2A (SV2A), and inhibit inositol 1,4,5-triphosphate receptors (IP3R) and ryanodine receptors (RyR) activated calcium-induced calcium release (CICR) (1)(3)(4). Voltage-gated calcium (Ca2+) channels are cellular membrane proteins that are important for electrical and chemical signaling in cells (5). In neurons voltage-gated Ca2+ chan... ... middle of paper ... ...Calcium Channels. Cold Spring Harbor Perspectives in Biology, 3(8). doi: 10.1101/ 6. Nowack, A., Yao, J., Custer, K. L., Bajjalieh, S. M. (2010). SV2 Regulates Neurotransmitter Release Via Multiple Mechanisms. American Journal of Physiology Cell Physiology 299(5). doi:10.1152/ajpcell.00259.2010 7. Lee, C.-Y., Chen, C.-C., & Liou, H.-H. (2009). Levetiracetam inhibits glutamate transmission through presynaptic P/Q-type calcium channels on the granule cells of the dentate gyrus. British Journal of Pharmacology, 158(7), 1753-1762. doi: 10.1111/j.1476-5381.2009.00463.x 8. Gillard, M., Chatelain, P., & Fuks, B. (2006). Binding characteristics of levetiracetam to synaptic vesicle protein 2A (SV2A) in human brain and in CHO cells expressing the human recombinant protein. European Journal of Pharmacology, 536(1–2), 102-108. doi: http://dx.doi.org/10.1016/j.ejphar.2006.02.022
The Role of Dopamine Receptors in Schizophrenia. Retrieved March 3, 2005, From Stanford University, Chemistry department web site, http://www.chem.csustan.edu/chem44x0/SJBR/Mann.htm Naheed, M., & Green, B. (2000). Focus on Clozapine. Retrieved February 7, 2005. From http://www.priory.com/focus14.htm Waddinton, J.L., & Buckley, P.F. (1996).
Action potentials in neurons are facilitated by neurotransmitters released from the terminal button of the presynaptic neuron into the synaptic gap where the neurotransmitter binds with receptor sites on the postsynaptic neuron. Dopamine (DA) is released into the synaptic gap exciting the neighboring neuron, and is then reabsorbed into the neuron of origin through dopamine transporter...
related amino acids are the dominant form of excitatory neurotransmitter in the central nervous system of
Weiner R. D., & Krystal, A.D. (February 1994). The present use of electroconvulsive therapy. Annual Review of Medicine, 45, 273-281.
γ-aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the CNS. GABAA is a ligand gated ion channel composed of five subunits. Through positive allosteric modulation ethanol binds to the δ subunit of the receptor and enhances the inhibitory effect of GABA. Once ethanol has bound to the GABAA receptor, chloride ions enter the post-synaptic neuron. This cascade of ions hyperpolarises the neuron, thus increasing inhibitory effects and makes the neuron less excitable. Ethanol alters the enzyme kinetics enabling the ion...
Epilepsy is a neurological disorder characterized by recurrent and uncertain intrusions of normal brain function, called epileptic seizure (Fisher et al., 2005). The word epilepsy was derived from the Greek word “attack”. The primitive Greeks thought epilepsy was contagious, and hence people with epilepsy used to live alone (Dam, 2003). It is one of the oldest conditions known to humankind (WHO, 2001a) and still the most common neurological condition affecting individuals of all ages. At any given time, it is appraise that 50 million individuals worldwide have a detection of epilepsy (WHO, 2001b). Epilepsy is charaterised by the incident of at least two unprovoked events of recurrent disruption in neurological function. Epilepsy is not a single prognosis but is a symptom with many fundamental causes. (Nunes et al., 2012).
Epilepsy, also known as “seizure disorder,” or “seizure attack,” is the fourth most common neurological disorder known to mankind, affecting an estimated 2.3 million adults and 467,711 children in the United States. Unfortunately this disorder is becoming far more common and widespread worldwide. This staggering number of cases of people suffering from Epilepsy also involves an average growth rate of 150,000 new cases each year in the United States alone. Generally, many of the people who develop who are a part of the new are mainly either young children or older adults. Your brain communicates through chemical and electrical signals that are all specialized for specific tasks. However, through the process of communication, chemical messengers, also known as neurotransmitters can suddenly fail, resulting in what is known as a seizure attack. Epilepsy occurs when a few too many brain cells become excited, or activated simultaneously, so that the brain cannot function properly and to it’s highest potential. Epilepsy is characterized when there is an abnormal imbalance in the chemical activity of the brain, leading to a disruption in the electrical activity of the brain. This disruption specifically occurs in the central nervous system (CNS), which is the part of the nervous system that contains the brain and spinal cord. This causes an interruption in communication between presynaptic neurons and postsynaptic neurons; between the axon of one neuron, the message sender and the dendrite of another neuron, the message recipient. Consequently, the effects that epileptic seizures may induce may range anywhere from mild to severe, life-threatening ramifications and complications. There are many different types of seizures associa...
First, the Electrical synapse relies on having two cells spanning across two membranes and the synaptic cleft between them (Shepard and Hanson, 2014, para. 2). Overall, the purpose of the Electrical synapse for the nervous system is for the synapse to carry out impulses and reflexes. On the contrary, the neuronal structure of the Synapse’s Chemical synapse involves the role of neurotransmitters in the nervous system. Located between the nerve cells, the gland cells, and the muscle cells, the Chemical synapse allows neurons for the CNS to develop interconnected neutral circuits. According to Davis (2007), “Interconnected logical computations that underlie perception and thought” (p.17). Generally, regarding the Chemical synapse’s role in the nervous system, this classification of the Synapse has a valuable role on how drugs affect the nervous system actions on synapses. As a result, the activity of the neurotransmitters becomes the key contributor for the Chemical synapse to effectively process drugs in the nervous system and throughout the human autonomy. Defines as a chemical released across the Synapse of a neuron, neurotransmitters manipulates the body to believe the drugs are neurotransmitters as well (Davis, 2007, p. 19). Significantly, the role of drugs in the human body help prevents the obliteration of neurotransmitters in the nervous system (Davis, 2007, p. 19).
Due to neurological studies of the brain, antipsychotic drugs have become the most widely used treatments. These studies show that there are widespread abnormalities in the structural connectivity of the brains of affected people. (2) It was noticed that in brains affected with schizophrenia, far more neurotransmitters are released between neurons, which is what causes the symptoms. At first, re...
This paper is going to discuss the condition Epilepsy. Epilepsy is defined as a disorder of the brain characterized by the recurrence of unprovoked seizures (Shorvon, 2009). Epilepsy starts in your brain, the brain is like a computer, it is made up of a mass of cells, called neurons, which connect to each other in very complicated ways (Routh, 2004). Electrical messages are constantly being passed from one neuron to another down nerves to the muscles in the body (Mair, 2004). If a person has epilepsy, these cells sometimes send a sudden, unexpected burst of electrical impulses, which causes a seizure (Routh, 2004). When the seizure finishes the brain behaves normally again. For some people with epilepsy these seizures happen every day. For others they may happen only once or twice a year (Routh, 2004). There are over 40 different types of seizure and each person is slightly different, but there are a few common types (Routh, 2004). Generalized seizures which affect the whole brain and partial seizures which affect a small part of the brain (Miller, 2013). The most common types of ge...
Epilepsy is a disorder of the brain characterized by an enduring predisposition to generate epileptic seizures,1 and by the neurobiological, cognitive, psychological and social consequences of this condition. An epileptic seizure is a brief disturbance of consciousness, behavior, emotion, motor function, or sensation that is due to abnormal electrical discharge in the brain.2 In partial-onset epilepsy, these bursts of electrical activity are initially focused in specific areas of the brain, but may become more generalized, with symptoms varying according to the affected areas. Epilepsy is the most common serious neurological condition in the UK.3 The World Health Organization (WHO) estimated its prevalence to be affecting approximately 5-8 per 1000 people.4 Anti-epileptic drugs (AEDs) are the major therapeutic option. Over a dozens of AEDs are introduced in the last 2 decades (Table 1.1). Between 1990 and 2011, 15 new antiepileptic drugs (AEDs) were approved by the US Food and Drug Administration (FDA) and/or by the European Medicines Agency (EMA). These drugs are Eslicarbazepine ace...
Epilepsy is a condition characterized by recurrent seizures which are unprovoked by any immediately identifiable cause (Hopkins & Shorvon, 1995). It is also known as a seizure disorder. A wide range of links and risk factors are associated with the condition, but most of the time the cause is unknown. Epilepsy is one of the most common neurological disorders, affecting approximately two and half million people in the US and about 50 million worldwide. Though seizures can occur at any age, epilepsy is most commonly seen in children and the elderly. Most respond well to treatment and can control their seizures, but for some it is a chronic illness. A clinical diagnosis is the first step to finding a potential cure for the disorder.
With 65 million people worldwide suffering from it, epilepsy is a growing health concern. One in twenty-six people will be diagnosed with epilepsy in the United States at some point in their lives. Epilepsy affects people of any age and any background (TEF, 2013). Sixty percent of cases are of unknown cause. Seizures affect different parts of the brain and result from different factors such as genetic, symptomatic, or idiopathic. Seizures can express themselves as partial (involved in one side of the brain) or generalized (involved in both sides of the brain), and as absent (the person stares blankly for a few seconds), atonic (person falls to the ground with loss of consciousness), tonic (the patient becomes very rigid and may or may not lose consciousness and falls to the ground), myoclonic (repetitive jerky motion) and tonic-clonic (a series of muscle stiffening and loosening and the patient loses consciousness and the patient falls to the ground). Patients can display signs of more than one type of seizure occurring in different parts of the brain (Solomon et. al., 2012). The condition is named epilepsy when the seizures are recurrent without any definitive trigger such as fever (Burns et. al., 2009).
Many drugs are available for the treatment of epilepsy, several of which have just recently been released, such as Perampanel which is the first of a new class of drugs. It appears to cause an excitatory response in the brain, and offers relief for drug addiction as well as epilepsy patients (Simon). There are many other relatively new drugs, and medical researchers are constantly developing more. All anti-epileptic drugs act as anticonvulsants. There are several anti-epileptic drugs like phenytoin, carbamazepine, and divalproex, which are considered the front-line drugs—the ones doctors try first; if patients do not respond well to them, doctors will move on to other drugs (Simon).
The inhibition occurs in both the brainstems and the spinal cord where strychnine competitively counteracts the activity of the neurotransmitters produced by the cells in the nervous system. The drug’s actions predominantly occur at the neuron synapse of the Renshaw cell-motors that are vital in connecting motorneurons. Preventing the binding between the post-synaptic receptors and glycine at the neuron synapse stops the post-synaptic channels from opening (Roy et al., 2012). Thus, severe neurological symptoms appear in the victim as the inhibitory signals fail to propagate in the nervous system. Excessive convulsions and motor neuron activities then occur due to the failure of the post-synaptic inhibition and accumulation of glycine in the brain. As a result, exaggerated responses to external stimuli such as touch, sound, and vision may arise in the central nervous system. This causes the restlessness, painful spasms, and agitation witnessed among individuals suffering from strychnine