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)

The biosynthesis and posttranslational processing of proenkephalin and the level of preproenkephalin mRNA were investigated in the mossy fiber system of the granule cells of the hippocampus in the presence or absence of a unilateral lesion of the hilus, a procedure that produces an episode of recurrent bilateral hippocampal seizures lasting several hours. Both immunocytochemistry and radioimmunoassay (RIA) have demonstrated that the hilus lesion leads to large bilateral increases in enkephalin immunoreactivity in the mossy fiber system. In the present study, RIA data indicate that following an initial decline in immunoreactivity, enkephalin content within the mossy fibers first begins to increase between 18 and 24 hr after lesioning. Using the technique of in vivo radiolabeling and high-performance liquid chromatographic purification of identified radiolabeled peptides, we observed a 14-fold increase in incorporation of radiolabeled methionine into Met5-enkephalin at 24-30 hr postlesion, as compared with control animals, when Met5-enkephalin was purified from the mossy fiber terminal fields. To examine the posttranslational proteolytic processing of proenkephalin, the biosynthesis of 5 additional Met5-enkephalin-containing peptides was also examined. We determined that the posttranslational processing of proenkephalin did not yield exclusively penta-, hepta-, and octapeptides but larger opioid peptides as well in both control and lesioned animals, and that the ratio of the enkephalin peptides was not altered following the lesion. Measurement of preproenkephalin messenger RNA levels in the granule cells by Northern analysis revealed a marked increase following the lesion. Compared with the control animals, preproenkephalin mRNA was 8.5-fold higher in the contralateral dentate gyrus at 12 hr postlesion and 14- to 15-fold higher by 24 hr.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Enkephalin biosynthesis and enkephalin gene expression are increased in hippocampal mossy fibers following a unilateral lesion of the hilus. 355 11

The influence of amygdaloid kindling on brain and pituitary content of immunoreactive dynorphin (IR-DYN) and other opioid peptides was studied in rabbits. The kindling was very effective in increasing the hippocampal levels of IR-DYN, alpha-neoendorphin and Leu-enkephalin, but remained without any significant effect on the levels of IR-DYN and beta-endorphin in the majority of brain structures studied. The concentration of IR-DYN in the hippocampus remained at the control level throughout the development but was increased dramatically after completion of kindling. Biochemical alterations persisted for at least one month following the completion of kindling. The obtained results suggest that the hippocampal IR-DYN and related peptides may play some role in the maintenance of amygdaloid-kindled seizures.
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PMID:Opioid peptides, particularly dynorphin, after amygdaloid-kindled seizures. 613 21

Microinjections of Leu-enkephalin were made in dorsal hippocampus, caudate nucleus, amygdala, nucleus accumbens and parietal cortex in rats. The effects of enkephalin on the local electrical activity recorded from the area of the microinjection are described. Depression effects (attenuation of amplitudes and slowing) were recorded in caudate nucleus, nucleus accumbens, amygdala and parietal cortex, but not in hippocampus. Activation and epileptiform effects (spikes, seizures) were recorded from all structures studied.
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PMID:Local electrographic effects of leu-enkephalin microinjections into the brain. 617 23

Pentylenetetrazol (PTZ) kindling was induced in male Wistar rats by daily i.p. injections of 40 mg/kg of the convulsant agent. IR-Met-enkephalin and IR-Leu-enkephalin were quantified in several brain regions 16 days after the last stimulus. In addition other rats received another PTZ dose on the sixteenth day and the samples were analyzed 1 and 24 h later. The results showed a long-lasting elevation in amygdala, septum, hypothalamus and hippocampus of IR-Met-enkephalin only. These brain structures also showed a decrease of IR-Met-enkephalin 1 h after the PTZ-induced seizure, but reached newly elevated levels 24 h later. IR-Leu-enkephalin levels only showed a decrease in striatum 1 h after PTZ-induced convulsions. The data suggest that Met-enkephalin is related to permanent changes in brain function induced by PTZ kindling, while Leu-enkephalin may depend on the occurrence of epileptic seizures.
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PMID:Pentylenetetrazol kindling produces a long-lasting elevation of IR-Met-enkephalin but not IR-Leu-enkephalin in rat brain. 672 31

Intracerebroventricular (i.c.v.) injections of the endorphins and of morphine in rats produce highly characteristic, naloxone sensitive, electrographic seizures. In contrast, systemic injections of morphine have been shown to exert a marked anticonvulsant effect. The present study demonstrates that systemic morphine pretreatment can prevent the occurrence of electrographic seizures injected by i.c.v. morphine, Leu-enkephalin and beta-endorphin and that the anti-epileptic effect of morphine can be reversed by naloxone. Male albino rats, previously prepared for chronic i.c.v. injections and EEG recordings, were pretreated with 0--100 mg/kg of intraperitoneal (i.p.) morphine. Thirty five minutes later morphine (520 nmol), Leu-enkephalin (80 nmol) or beta-endorphin (5 nmol) were injected i.c.v. Pretreatment with i.p. morphine blocked the occurrence of seizures induced by morphine and both endogenous opioids. Lower doses of systemic morphine (50 mg/kg) were necessary to block i.c.v. morphine seizures than the dose (100 mg/kg) necessary to block seizures induced by i.c.v. Leu-enkephalin and beta-endorphin. Naloxone (1 mg/kg) administered 25 min following 50 mg/kg of i.p. morphine and preceding the injections of i.c.v. morphine reversed the antiepileptic effect of systemic morphine. These results demonstrate the possible existence of two opiate sensitive systems, one with excitatory-epileptogenic effects and the other possessing inhibitory-antiepileptic properties. The possible relationship between these findings and the known heterogeneity of opiate receptors and opiate actions is discussed.
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PMID:Systemic morphine blocks the seizures induced by intracerebroventricular (i.c.v.) injections of opiates and opioid peptides. 712 82

The opioid peptides Leu-enkephalin, Met-enkephalin and D-Ala2-Met-enkephalinamide were injected at various concentrations into the neocortex and hippocampus of rats to examine their effects on EEG activity and DC potentials. All three compounds were found to elicit spreading depression (SD) in both structures. Higher doses of Met-enkephalin were required to elicit SD as well as seizure activity. In the hippocampus the wave of SD was frequently preceded by seizure activity which was antagonized by naloxone pretreatment (40 mg/kg i.p.). Naloxone also prevented Leu-enkephalin-induced SD in the neocortex (but not in the hippocampus) and Met-enkephalin-induced SD in the hippocampus (but not in the neocortex). It failed to block SD elicited by D-Ala2-Met-enkephalinamide in both structures. Some of the various reported behavioral effects of intracranial injections of enkephalins could be artefacts of hippocampal and/or cortical spreading depression.
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PMID:Spreading depression induced by microinjection of enkephalins into the hippocampus and neocortex. 722 10

Brain content of leucine-enkephalin and methionine-enkephalin changes independently during kindling of the amygdala. Both peptides were measured after 4, 8, 15 and 21 days of stimulation. Leu-enkephalin showed a progressive increase during the kindling: the results on the 4th day did not differ significantly from the controls, whereas those on the 8th day displayed an increase only in the stimulated left hemisphere and those on the 15th day showed an increase in both hemispheres. This increase was also seen after 21 days of stimulation. In contrast, Met-enkephalin was not modified during the early stages of kindling, but was found to be increased after the animals had presented five or more generalized seizures. These results show that Leu-enkephalin is related to the development of kindling, whereas Met-enkephalin levels change only as a consequence of the generalized seizures.
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PMID:Brain content of leu5- and met5-enkephalin changes independently during the development of kindling in the rat. 730 Dec

We determine the opioid peptide content in the rat brain during the ictal phase and postictal depression after pentylenetetrazol kindling rats. Radioimmunoassays with highly specific antisera risen for Met-enkephalin, Leu-enkephalin and octapeptide, were carried out during the ictal phase, and 15, 30 and 60 min after seizures. We always found an initial IR-Met-enkephalin decrease during the postictal depression content, followed by a reduction in IR-Leu-enkephalin and IR-octapeptide tissular concentration. We suggest a functional and differential release of the opioid peptides, during the postictal depression time-course.
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PMID:Opioid peptides content in the rat brain during the ictal phase and after pentylenetetrazol-kindled rats. 755 33

Expression of the opioid peptides dynorphin and enkephalin is altered within the first 24 h after acutely induced seizures in certain experimental models of epilepsy. Using in situ hybridization, we examined the expression of prodynorphin and preproenkephalin messenger RNA acutely following induction of kindling with recurrent seizures and in two models of chronic temporal lobe epilepsy: (i) rats fully kindled with rapidly recurring hippocampal seizures; and (ii) rats surviving after self-sustaining limbic status epilepticus induced with focal electrical stimulation of the hippocampus. In naive animals, a ventral-dorsal gradient was identified in the expression of both prodynorphin and preproenkephalin messenger RNA in the dentate gyrus and expression of prodynorphin message was demonstrated for the first time in the ventral portion of cornu Ammonis regio superior. After stimulation producing rapidly recurring hippocampal seizures, acute decreases in prodynorphin messenger RNA were seen in the dentate gyrus and cornu Ammonis regio superior at 24 h after the last seizure. In contrast, increases in preproenkephalin messenger RNA expression were seen acutely in the dentate gyrus, with a decrease seen in the entorhinal cortex. The change in prodynorphin message expression in cornu Ammonis regio superior persisted in kindled animals that were studied after one month seizure-free period. There were no changes in preproenkephalin message in kindled animals studied after the one month seizure-free interval. No statistically significant changes were found for either prodynorphin or preproenkephalin message in the post-self-sustaining limbic status epilepticus group at one month following induced seizures. Acute changes in peptide expression may contribute to increased excitation in the dentate gyrus during induction of kindling, while the chronic change identified in cornu Ammonis regio superior may contribute directly to persistently increased excitability in this region.
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PMID:Opioid peptide expression in models of chronic temporal lobe epilepsy. 760 77

Our previous studies have shown that seizure induced by injecting penicillin (0.24 mg/2 microliters) into hippocampus could be inhibited by electroacupuncture (EA) probably via decreasing enkephalin content in hippocampus. To determine whether this change reflected the peptide synthesis, preproenkephalin (PPE) mRNA was detected in hippocampus and some other limbic structures during seizure and after EA treatment by in situ hybridization. Four hours after injecting penicillin into hippocampus, PPE mRNA levels were significantly increased by 10 folds in entorhinal cortex, subiculum, CA1 area of hippocampus, amygdaloid nucleus and piriform cortex, whereas EA treatment apparently attenuated the seizure-induced increase of PPE mRNA in the areas mentioned above. The results indicated that EA may regulate the biosynthesis of PPE in hippocampus during seizure by an alteration in gene transcription.
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PMID:Effect of electroacupuncture on the level of preproenkephalin mRNA in rat during penicillin-induced epilepsy. 786 37


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