Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0036572 (seizures)
 80,221 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Based on the previously reported co-localization and relationship between cannabinoid and dopamine receptors, the effects of cannabinoid receptor agonists against cocaine-induced toxic behavioural symptoms, including convulsive seizures, were examined in mice. The anticonvulsant effect of several cannabimimetics against seizures induced by other convulsants was also compared. The cannabinoid receptor agonists CP 55940 ((-)-cis-3-[2-hydroxy-4-(1,1-dimethylheptyl)phenyl]-trans-4-(3-hydroxypropyl)-cyclohexanol) and WIN 55212-2 ((R)-(+)-[2,3-dihydro-5-methyl-3-(4-morpholinylmethyl)pyrrolo[1,2,3-de]-1,4-benzoxazin-6-yl]-1-naphthalenylmethanone), and the endogenous cannabinoid anandamide were co-administered intraperitoneally with cocaine (75 mg kg(-1)) or other convulsants such as bicuculline, methyl 6,7-dimethoxy-4-ethyl-beta-carboline-carboxylate (DMCM), L-glutamic acid and N-methyl-D-aspartate (NMDA). CP 55940 (2.5 mg kg(-1)) and anandamide (15 mg kg(-1)) significantly antagonized cocaine-induced lethality, and CP 55940 and WIN 55212-2 (2.5 mg kg(-1)) significantly attenuated the severity of cocaine-induced convulsive seizures. Furthermore, ataxic hyperactivity, which was observed only in the cocaine-treated group of mice and could be evaluated by their activity counts, was also depressed in the groups of mice co-treated with each of the three cannabinoid agonists. However, none of these agonists protected against bicuculline- or DMCM-induced lethality or convulsive seizures. In contrast, all of the cannabinoid agonists, most notably anandamide, antagonized both L-glutamic acid (2 g kg(-1))- and NMDA (200 mg kg(-1))-induced convulsive seizures. These data support the previously reported close correlation between dopamine and cannabinoid receptors, and between cannabinoid agonists, especially anandamide, and glutamate (NMDA) receptors. Furthermore, these results suggest a potential therapeutic role for cannabinoid agonists against cocaine- and other-convulsant-induced toxicities.
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PMID:Protective effects of cannabinoid receptor agonists against cocaine and other convulsant-induced toxic behavioural symptoms. 1173 55

The interaction of neurotransmitters has been a major interest in pathophysiological conditions like epilepsy. In vivo microdialysis has recently gained much validity in measuring neurotransmitter release in experimental animals. However, there is a paucity of data concerning its use in humans on the grounds of safety considerations. Microdialysis experiments were performed using the hippocampal head region removed from patients with medically intractable seizures, who underwent surgery for mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS). Following en bloc resection, the tissues were immediately transferred to the essential in vitro milieu. Slices were incubated in lactated Ringer's solution and microdialysis probes inserted into the slices were perfused with artificial cerebrospinal fluid (aCSF). When the K+ concentration of aCSF was elevated to 100 mM, GABA and L-glutamic acid levels increased by 293% and 177%, respectively. This method may serve as an experimental model for human brain, to throw more light on the interactions between GABA and L-glutamic acid in hippocampal tissues obtained from patients with MTLE-HS.
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PMID:GABA and L-glutamic acid release in en bloc resection slices of human hippocampus: an in vitro microdialysis study. 1180 52

Urea Cycle Disorders (UCD) is an inborn error of urea synthesis in which ammonium and other nitrogenous precursors of urea accumulate leading to episodic coma and a high mortality rate. Therapy with peritoneal dialysis, essential amino acids or their nitrogen-free analogues has increased survival. The authors report 5 cases of urea cycle disorders, all of whom developed and were rescued from hyperammonemic coma. However, the eventual outcome was quite variable. Argininosuccinate lyase deficiency (ALD) Case 1. A 2 month old male infant, a product of a consanguineous marriage (Suphanburi province); developed poor feeding on day 7, lethargy, convulsion, hepatomegaly and respiratory alkalosis leading to respiratory failure and coma. Hyperammonemia, elevation of glutamic acid and argininosuccinic acid and its anhydrides confirmed the diagnosis of ALD. He is now 9 years old and severely retarded. Case 2. A male infant with history of lethargy, poor feeding on day 3, treated as sepsis and required respiratory support for 6 days; subsequently readmitted at age 2 weeks with vomitting, lethargy, seizure activity and hyperammonemia, and was treated by a local pediatrician in Songkhla province. There was a history of parental consanguinity and he was referred to Siriraj Hospital on day 64 with severe essential amino acid deficiency and acrodermatitis enteropathica with markedly elevated plasma citrulline level. In spite of aggressive treatment; the patient developed sepsis and he expired on day 78. Ornithine transcarbamylase deficiency (OTC) Case 3. An eleven-month-old male infant, the product of a non-consanguineous marriage, developed neonatal onset of hyperammonemia on day 5 after poor feeding, lethargy, hypothermia, seizure, apnea and coma. He was rescued from neonatal hyperammonemic coma on day 9 after aggressive treatment, but expired at eleven months of age after overwhelming sepsis. Case 4. A male infant, sibling of case 3 was referred to Siriraj Hospital on day 8 with hyperammonemia and coma. In spite of intensive genetic counseling given after the birth of their first child with OTC, the couple chose to have another baby without informing any physician. The baby developed vomiting and lethargy on day 2; subsequently hyperammonemia was noted. In spite of aggressive treatment given; hepatic dysfunction, renal failure and disseminated intravascular coagulation defects occurred on day 15. He expired on day 18 after parental permission for discontinuation of all treatment. Argininosuccinate synthetase deficiency (ASS) or Citrullinemia. Case 5. A seven week old female infant, the product of a consanguineous marriage and of Pakistani ethnic origin; developed intermittent vomiting from day 6. Initial diagnoses included ruminations, sepsis and pyloric stenosis for which she was operated on (day 30); however, vomiting continued; subsequently seizures, hyperammonemic coma developed and she was rescued from hyperammonemic coma within 30 hours. Significant elevations of citrulline and L-glutamine were demonstrated. She was discharged in excellent condition to her home in Dubai, the United Arab Emirates.
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PMID:Urea cycle disorders in Thai infants: a report of 5 cases. 1240 52

To study the antiepileptic mechanism of vagus nerve stimulation (VNS), we used the methods of in situ hybridyzation and image analysis to detect the expression of NMDAR1 mRNA and GABAA receptor alpha 1 subunit mRNA (GABAAR alpha 1 mRNA) in the thalamic reticular nuclus. The results show that the NMDAR1 mRNA expression of rats administered pentylenetetrazole(PTZ) is higher than that of control group. By treating with VNS, it decreased. On the contrary, the expression of GABAAR alpha 1 mRNA in the thalamic reticular nuclus of PTZ group rats is lower than that of control group. For rats treated with VNS, it increased. Therefore, it is concluded that VNS may reduce the excitability of cerebral cortices by depressing the activities of glutamic acid receptors (GluR) and by promoting the activities of gamma-aminobutyric acid receptors(GABAR) in thalamic reticular nuclus. So the formation and development of seizures are inhibited.
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PMID:[The influence of vagus nerve stimulation on NMDAR1 mRNA and GABAAR alpha 1 mRNA in thalamic reticular neucus of pentylenetetrazole-induced epileptic rats]. 1256 48

Epilepsy affects homeostasis and autonomic nervous system functions. It has been thought that the dysfunction in the autonomic neural mechanisms could be a cause of sudden unexpected death in patients with epilepsy. The kindling model of epilepsy is considered to be an animal model for complex partial seizures with secondary generalization. The objectives of this study were to investigate the extracellular gamma-aminobutyric acid (GABA), glutamate, noradrenaline and dopamine levels in the dorsomedial nucleus of the hypothalamus in non-epileptic and kindled epileptic rats and to explain some of the cardiovascular changes in the kindling model of epilepsy. Stimulation electrodes were stereotaxically implanted into the basolateral amygdala and electrical stimulation was applied 3 times a day at a constant current. The rats were then kindled to full stage 5 seizures. Microdialysis experiments were performed to demonstrate the neurotransmitter levels in the dorsomedial nucleus of the hypothalamus 3-5 days after being kindled. Decreases in noradrenaline and dopamine levels in the dorsomedial nucleus were detected in the conscious kindled animals. This finding is in agreement with prior findings that the noradrenergic system has a negative role in the process of kindling. The basal level of glutamic acid and GABA remained unchanged in the kindled group when compared to non-epileptic animals, and similarly, neither blood pressure nor heart rate responses to bicuculline or N-methyl-D-aspartate were affected by the acute kindled state. These findings suggest that the autonomic changes in kindling require further studies.
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PMID:Extracellular concentrations of catecholamines and amino acids in the dorsomedial hypothalamus of kindled rats. A microdialysis study. 1283 73

The delta(2)- 1,2,3- triazoline anticonvulsants (TRs) may be considered as representing a unique class of "built-in" heterocyclic prodrugs where the active "structure element" is an integral part of the ring system and can be identified only by a knowledge of their chemical reactivity and metabolism. Investigations on the metabolism and pharmacology of a lead triazoline, ADD17014 suggest that the triazolines function as "prodrugs" and exert their anticonvulsant activity by impairing excitatory amino acid (EAA) L-Glutamate (L-Glu) neurotransmission via a unique "dual-action" mechanism. While an active primary beta-amino alcohol metabolite from the parent prodrug acts as an N-methyl-D-aspartate (NMDA)/MK -801 receptor antagonist, the parent triazoline impairs the presynaptic release of L-Glu. Various pieces of theoretical reasoning and experimental evidence have led to the clucidation of the dual-action mechanism. Based on the unique chemistry of the triazolines, and their metabolic pathways, biotransformation products of TRs were predicted to be the beta-amino alcohols V and VA, the alpha-amino acid VI, the triazole VII, the aziridine VIII and the ketimine IX. In vivo and in vitro pharmacological studies of the TR and potential metabolites, along with a full quantitative urinary metabolic profiling of TR indicated the primary beta-amino alcohol V as the active species. It was the only compound that inhibited the specific binding of [3H]MK-801 to the MK-801 site, 56% at 10 micro M drug concentration, but itself had no anticonvulsant activity, suggesting TR acted as a prodrug. Three metabolites were identified; V was the most predominant (45.7 +/- 7.6) % of administered drug, with lesser amounts of VA, (17.3 +/- 5.1) % and very minor amounts of aziridine VIII (4.0 +/- 0.02)%. Since only VIII can yield VA, its formation indicated that the biotransformation of TR occurred, at least in part, through aziridine. No amino acid metabolite was detected, which implied that no in vivo oxidation of V or oxidative biotransformation of TR or aziridine by hydroxylation at the methylene group occurred. While triazoline significantly decreased Ca(2+) -dependent, k(+)-evoked L-Glu release (83% at 100 micro M drug concentration ), some triazolines showed an augmentation of 50-63%, in the Cl(-) channel activity, a useful membrane action that reduces the excessive L-Glu release that occurs during epileptic seizures. The high anticonvulsant activity of TRs in a variety of seizure models including their effectiveness in the kindling model of complex partial seizures may be due to their unique dual-action mechanism whereby the TR and V together effectively impair both pre- and postsynaptic aspects of EAA neurotransmission; thus the TRs have clinical potential in the treatment of complex partial epilepsy which is refractory to currently available drugs. Since there is strong evidence that L-Glu plays an important role in human epilepsy as well as in brain ischemia/stroke, and since the TRs act by inhibiting EAA neurotransmission, it was logical to expect that the anticonvulsant TRs may evince beneficial therapeutic potential in cerebral ischemia resulting from stroke as well. And indeed, several TRs, when tested in the standard gerbil model of global ischemia did evince remarkable ability to prevent neuronal death.
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PMID:Rational drug design and the discovery of the delta2-1,2,3-triazolines, a unique class of anticonvulsant and antiischemic agents. 1287 Oct 87

gamma-Aminobutyric acid (GABA) is the primary inhibitory neurotransmitter in the central nervous system. GABA is converted from glutamic acid by the action of glutamic acid decarboxylase (GAD) of which two isoforms exist GAD65 and GAD67. GABA then is broken down, both within the cell and in the synaptic cleft by GABA transaminase to form succinic semialdehyde. In turn, succinic semialdehyde is converted either to succinic acid by succinic semialdehyde dehydrogenase or into gamma-hydroxybutyric acid (GHB) by succinic semialdehyde reductase. Because GABA modulates the majority of inhibition that is ongoing in the brain, perturbations in GABAergic inhibition have the potential to result in seizures. Therefore, the most common disorder in which GABA is targeted as a treatment is epilepsy. However, other disorders such as psychiatric disease, spasticity, and stiff-person syndrome all have been related to disorders of GABAergic function in the brain. This review covers the roles of GABAergic neurotransmission in epilepsy, anxiety disorders, schizophrenia, stiff-person syndrome, and premenstrual dysphoric disorder. In the final section of this review, the GABA metabolite GHB is discussed in terms of its physiological significance and its role in epilepsy, sleep disorders, drug and alcohol addiction, and an inborn error of GABA metabolism, succinic semialdehyde dehydrogenase deficiency.
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PMID:GABA, gamma-hydroxybutyric acid, and neurological disease. 1289 48

1. Increases in the concentrations of lactic acid and pyruvic acid in rat brain during acute dieldrin poisoning are associated with hyperactivity of the brain, whereas an increase in the cerebral alanine concentration occurs before the convulsions. Throughout the dieldrin-induced seizure pattern, fluctuations in the concentration of brain ammonia are out of phase with the actual convulsions. 2. Increases in the concentrations of alanine, ammonia and lactic acid in rat brain accompany picrotoxin-induced seizures; there is no increase in the concentration of glutamine. These changes are consistent with the inhibition of glutamine synthesis. 3. In addition to previously reported changes in the concentrations of intermediary metabolites of the brain after the administration of Telodrin (Hathway & Mallinson, 1964), increases have now been found in the alanine and lactic acid concentrations. Since increases in the alanine and glutamine concentrations occur before the convulsions, liberation of ammonia also occurs before the onset of convulsions and throughout their course. Ammonia-binding mechanisms later become inadequate and free ammonia accumulates in cerebral tissues. 4. An increase in the pyruvic acid concentration of the brain after the intraperitoneal injection of either dieldrin or Telodrin is endogenous in origin. 5. The parenteral administration of a small dose of glutamine increases the cerebral concentrations of alanine and glutamic acid. Some animals previously treated with glutamine resisted Telodrin convulsions. 6. Mechanisms for the disposal of ammonia liberated in brain are discussed.
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PMID:EFFECTS OF DIELDRIN, PICROTOXIN AND TELODRIN ON THE METABOLISM OF AMMONIA IN BRAIN. 1434 58

In our previous studies for the development of new anticonvulsant of broad spectrum, we found that N-cbz-alpha-aminoglutarimides showed significant anticonvulsant activities of broad spectrum enough to be recommended for the new anticonvulsants and their anticonvulsant activities were dependent on their imide substituent groups. Based on these results, various N-cbz-alpha-amino-N-alkoxyglutarimides, where the imide N-H was substituted with the hydroxy and alkoxy group, were prepared and evaluated for their anticonvulsant activities using the Maximal electroshock seizure (MES) and Pentylenetetrazole induced seizure (PTZ) tests and also the rotorod test. A series of (R) or (S)-N-cbz-alpha-amino-N-alkoxyglutarimides could be prepared from the corresponding (R) or (S)-N-cbz-glutamic acid following the usual synthetic procedure. Among them, (R)-N-cbz-alpha-amino-N-hydroxyglutarimide (ED50=86.25 mg/kg) was most active in the MES test. In the case of the PTZ test, (R)-N-cbz-alpha-amino-N-benzyloxyglutarimide (ED50=62.5 mg/kg) was most active. Among the tested compounds, 2a-c, 3a, and 3b showed anticonvulsant activities in the MES and PTZ test. All of the tested compounds, except 2f and 3f, showed significant anticonvulsant activities in the MES or PTZ test. In addition, the neurotoxicities of these compounds were comparable to other anticonvulsant drugs.
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PMID:Synthesis and anticonvulsant evaluations of N-cbz-alpha-amino-N-alkoxyglutarimides. 1502 14

Epilepsy is the most common primary neurological disorder known. Epileptiform neurons undergo paroxysmal depolarization shifts (PDS), which result in the excessive sustained neuronal firing seen in epilepsy. These shifts are due to either an impairment of GABA mediated inhibition, or an enhancement of aspartate or glutamate mediated excitatory transmission. Recent research has focused on the cellular biology of seizures. 4-Aminobutyric acid (GABA) is a major inhibitory neurotransmitter of mammalian central nervous system. In neural and nonneural tissues, GABA is metabolized by three enzymes-glutamic acid decarboxylase (GAD), which produces GABA from glutamic acid, and the catabolic enzymes GABA-transaminase (GABA-T) and succinic semialdehyde dehydrogenase (SSADH). Production of succinic acid by SSADH allows entry of the GABA carbon skeleton into the tricarboxylic acid cycle. GABA-T is present in a variety of circulating cells, including platelets and lymphocytes. SSADH, the final enzyme of GABA catabolism, has been detected in some of the tissues in which GAD and GABA-T have been identified. This paper is aimed at elucidating the organization of the GABA shunt and covers a review on the antiepileptic drugs, both established and currently under development targeted to the GABA shunt in order to bring about effective seizure control.
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PMID:The GABA shunt: an attractive and potential therapeutic target in the treatment of epileptic disorders. 1585 64


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