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Query: UMLS:C0036572 (seizures)
 80,221 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Dose-effect and time course relationships were determined for the effects of the explosive cyclotrimethylenetrinitramine (RDX) on seizure susceptibility. Male Long Evans rats treated with 0-60 mg/kg RDX po were monitored for spontaneous seizures during an 8-hr interval between dosing and audiogenic (AG) seizure testing. Blood samples for analyzing plasma RDX concentrations were obtained immediately thereafter. Spontaneous and AG seizures were observed at dosages as low as 10-12.5 mg/kg, with significant seizure incidence induced by dosages of 25.0 mg/kg (5.34 micrograms RDX/ml plasma) and 50.0 mg/kg (8.28 micrograms RDX/ml plasma), respectively. Spontaneous seizure incidence peaked at 2 hr for all RDX treatment groups, then decreased (12.5 and 25.0 mg/kg) or remained elevated (50.0 mg/kg) for the remaining 6 hr. In contrast, AG seizures (37.5 mg/kg) could be elicited only at 8 and 16 hr, despite significant elevation of plasma RDX concentrations at 2 and 4 hr. Because limbic system involvement was suggested by spontaneous seizure characteristics, the rate of amygdaloid kindling was measured following daily treatment with 6.0 mg/kg. This dosage significantly accelerated kindling development without inducing spontaneous seizures or producing an accumulation of RDX in plasma. These data provide preliminary evidence that limbic structures may participate in RDX-induced seizure susceptibility.
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PMID:Convulsant properties of cyclotrimethylenetrinitramine (RDX): spontaneous audiogenic, and amygdaloid kindled seizure activity. 335 89

Two experiments were conducted using microwave hyperthermia (MHT) to induce seizures among limited numbers of Long-Evans rat pups. The MHT model of febrile seizures eliminates several methodological complications inherent in previous animal models of the disorder. In Experiment 1, rat pups were rendered hyperthermic with MHT or were sham-irradiated on Days 11, 13, 15 or 17 postpartum. The results indicate a statistically significant decline in seizure susceptibility with age. In Experiment 2, rats were subjected to either single or multiple hyperthermic episodes on Days 11, 13, 15, or 17 postpartum. The results indicate an increase in susceptibility to seizures attributable to prior seizure history. In both experiments, seizures were induced with increases in rectal temperature of 1 to 3 degrees C. The results parallel many clinical features of febrile seizures and argue the efficacy of the MHT model.
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PMID:Ontogeny of susceptibility to experimental febrile seizures in rats. 337 58

Male Long-Evans rats experienced three convulsions induced by intravenously administered pentylenetetrazol (PTZ) and were then kindled by electrical stimulation of the olfactory bulb or amygdala. Pretreatment with PTZ did not alter the rate of kindling in either site but did enhance the expression of kindled seizures once generalization had occurred (PTZ-treated animals had significantly longer motor seizures, measured by clonus duration, than did saline-treated controls). This suggests that PTZ-induced convulsions have selective effects on areas of the brain that are involved in the expression of the motor seizure. In addition, rats treated with PTZ after kindling had convulsions that were significantly longer in duration than any of their three pre-kindling convulsions, indicating that kindling produced an increased sensitivity to PTZ's convulsant effects. Comparison of this experiment with previous research suggests that the ability of a drug treatment to generate a kindling-like effect is related to the pattern of seizure activity that it produces.
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PMID:Effect of pentylenetetrazol-induced convulsions on the development and expression of limbic kindled seizures. 356 86

At the age of 31 days, Long-Evans female rats received electrolytic lesions either of the medial fimbria (N = 24), of the dorsal subcallosal fornix (N = 24), or of both structures (N = 24). Ten rats were used as sham-operated controls. Ten days later, half the rats of each lesion group received intrahippocampal grafts of acetylcholine-rich fetal basal forebrain cell suspensions. Twelve months after grafting, all surviving rats, except six grafted rats which became very difficult to handle (because they developed convulsive behavior) were tested for reactivity to pentylenetetrazol (30 mg/kg, i.p.) and to sound (120 dB, 90 s). Grafted rats were found to be more reactive to the drug and less reactive to sound than their nongrafted counterparts with similar lesions. Reactivity to pentylenetetrazol of grafted rats was correlated with body weight and extent of graft-induced hippocampal damage, but not with graft size. Reactivity to sound, which was apparently not dependent on hippocampal damage or graft size, might be related to enhanced graft-derived cholinergic activity in the hippocampus. Our results show that intrahippocampal septal grafts interfere in opposite directions with the seizure-inducing treatments used, so that it can be assumed that the physiologic mechanisms by which grafts do so and by which these treatments induce seizures are likely to be different.
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PMID:Susceptibility to pentylenetetrazol-induced and audiogenic seizures in rats with selective fimbria-fornix lesions and intrahippocampal septal grafts. 362 10

Vitamin B-6 deficient rats exhibit changes in behavior, sensory function, and other nervous system abnormalities such as convulsive seizures and motor disturbances. Sensorimotor reactivity was evaluated quantitatively by measuring auditory and tactile startle responses in 12 week old female Long-Evans rats fed a diet devoid of added vitamin B-6 (DEF) or a control diet, either ad lib (AL-CON) or pair-fed to deficient rats (PF-CON). Deficiency was confirmed with a tryptophan-load test administered to a separate group of rats fed simultaneously according to the same protocol. At week 18, body weight and feed efficiency were different among groups (p less than 0.001), and were lowest in DEF. Amplitude of response to both acoustic and tactile stimuli was depressed in DEF compared to both control groups, which generally did not differ in response. This effect was seen most dramatically in responses to the acoustic stimulus (p = 0.034), and especially to the first presentation (p = 0.017). Latency to maximum response was not affected by diet. Possible mechanisms for this nervous system abnormality, not previously reported in vitamin B-6 deficiency, are discussed.
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PMID:Attenuation of acoustic and tactile startle responses of vitamin B-6 deficient rats. 362 44

This study explored the anticonvulsant effects of adenosine analogs at the focus of seizures kindled from various brain structures. Chemitrodes were implanted in the amygdala (AM), hippocampus (HIPP), or caudate nucleus (CN) of Long-Evans rats and electrically stimulated once daily until fully generalized seizures appeared (i.e., kindled). Once kindled, various doses (0.001-0.5 microgram/0.5 microliter) of the adenosine analogs, L-phenylisopropyladenosine (L-PIA), N-ethylcarboximidoadenosine (NECA) or vehicle were injected into the seizure focus 5 min prior to electrical stimulation. The afterdischarge (AD) and behavioral seizure stages were measured. L-PIA had potent anticonvulsant effects when injected directly into the kindled seizure focus in the AM, HIPP, or CN. NECA effects were statistically significant only in CN-kindled seizures. The regional differences in efficacy of the two adenosine analogs suggest that L-PIA, an A1 adenosine subtype agonist, may exert its effects through A1 adenosine receptors in the AM, HIPP, and CN, where A1 binding has been demonstrated, whereas NECA, an A2 adenosine receptor agonist, may only be maximally effective in the CN where A2 adenosine binding sites are located.
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PMID:Differential effects of adenosine analogs on amygdala, hippocampus, and caudate nucleus kindled seizures. 369 15

Numerous problems have been associated with previous attempts to develop a suitable method for the induction and assessment of alcohol dependence and withdrawal syndrome in the rat. Using our modification of a common inhalation method for the long-term administration of ethanol, these problems can be eliminated. Adult male rats (Long Evans and Brattleboro) were exposed to ethanol vapor concentrations of 7 to 35 mg/liter of air, which cause rapid development of tolerance and physical dependence. With this inhalation method, it is possible to obtain and easily maintain high levels of ethanol in the blood (150 to 400 mg/dl). When exposure to ethanol is terminated, ethanol is eliminated from the system within 1 to 6 hr. This rapid elimination of ethanol is accompanied by a high susceptibility to withdrawal reactions. The severity of the withdrawal syndrome was assessed within 6 to 24 hr after cessation of the ethanol administration by exposing each rat individually to a 60 to 120-sec period of bell ringing. Convulsive seizures were observed in nearly 90% of the animals tested, with a mortality rate of less than 20%.
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PMID:Alcohol dependence and withdrawal in the rat. An effective means of induction and assessment. 371 3

Long-Evans dams were fed either a vitamin B6-deficient or a control diet from day 13-14 of gestation and throughout lactation. A control pair-fed group was also included because of differences in food intake between vitamin B6-deficient and control ad libitum dams. The progeny of vitamin B6-deficient dams had all the classic symptoms of B6 deficiency. These included weight loss, ataxia, tremor, and epileptic seizures. Concentrations of the neurotransmitter dopamine (DA), and its metabolites 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), as well as D-2 dopamine receptor binding, 3,4-dihydroxyphenylalanine (DOPA) decarboxylase activity, and vitamin B6 levels were measured in the corpus striatum of progeny at 7, 14, and 18 days after birth. Striatal DA and HVA levels were significantly decreased in B6-deficient animals when compared to ad libitum or pair-fed controls. Daily injections of vitamin B6 to deprived animals from the 14th to 18th day after birth improved the abnormal movement and normalized the concentration of DA but not of HVA in corpus striatum. Striatal D-2 dopamine receptor binding using [3H]spiperone as ligand was significantly reduced in 18-day-old animals as compared to ad libitum and pair-fed controls. No significant differences were found at 14 days. The administration of vitamin B6 to deprived animals did not raise the level of D-2 receptor binding during the period of observation. Scatchard plots indicated that the differences in binding were due to changes in receptor number and not in KD. Corpus striatum DOPA decarboxylase activity with and without the addition of exogenous pyridoxal phosphate was significantly reduced in 14- and 18-day-old animals when compared to pair-fed controls.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effects of perinatal vitamin B6 deficiency on dopaminergic neurochemistry. 379 15

Long-Evans, hooded rats were intubated with one of four dose combinations of pentazocine and tripelennamine on Days 7-20 of pregnancy: 0:0 (mg/kg pentazocine:tripelennamine), 20:10, 40:0, or 40:20. An additional group had free access to lab chow and water throughout pregnancy. At birth, reduced body weights were evident in all drug-treated offspring. Growth deficits were not noted at 5, 10, 15 or 20 days of age. Three measures of activity were collected at 18 days of age, however, none of these measures were differentially affected as a function of prenatal treatment. At 85 days of age, offspring were tested in a two-way shuttle avoidance paradigm. Although the number of avoidances was not significantly affected by prenatal treatment, offspring exposed to these drugs in combination had shorter response latencies than controls with increased training and made more intertrial crossing responses. Additional offspring were tested for seizure susceptibility at 100 days of age. None of the parameters of seizure activity were significantly affected by prenatal drug treatment. Prenatal exposure to pentazocine and tripelennamine resulted in prenatal growth deficits, increased activity during the intertrial interval and decreased response latencies in a shuttle avoidance learning task, suggesting that this polydrug combination may be associated with some long-term behavioral teratogenic risks.
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PMID:Behavioral and developmental effects of prenatal exposure to pentazocine and tripelennamine combinations. 380 75

A study of bio-availability of three drug companies' brands of phenytoin preparations (50mg capsule/tablets) was undertaken on 30 children with tonic-clonic or complex partial seizures. Eight children were excluded because of non-compliance and three because of abnormally high serum levels. Phenytoin capsules (Parke Davis) and tablets (Boots) produced significantly higher serum-level profiles than phenytoin tablets (Evans). Seizure frequencies did not differ significantly with the three brands of phenytoin. Dissolution of the three preparations tested in vitro was different. As a result of this study the authors recommend that children remain on the same manufacturer's brand of phenytoin throughout their treatment.
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PMID:Bio-availability and dissolution of three phenytoin preparations for children. 381 9


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