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

We studied the effect of pentylenetetrazol (PTZ)-induced kindling (35 mg/kg, i.p., daily) on somatostatin-like immunoreactivity (SOM) with special attention to the duration of changes (rats were sacrificed either 10 days or 4 months after the development of kindling) and to transmitters or modulators related to somatostatin (neuropeptide Y (NPY), GABA, choline acetyltransferase (ChAT), acetylcholinesterase (AchE]. In rats sacrificed 10 days after the last kindled seizure, SOM was elevated in frontal cortex and striatum (p less than 0.01); NPY was elevated in frontal cortex, striatum and hippocampus (p less than 0.05) of kindled or prekindled rats (i.e., rats which were treated daily with PTZ but did not express three consecutive generalized seizures). ChAT activity was slightly decreased (p less than 0.05) in cortex. GABA levels and AchE activity were unchanged in kindled cortex. In rats sacrificed 4 months after the development of kindling none of the parameters analyzed differed from controls. The present study suggests that the cortical and striatal neurons containing SOM/NPY are affected by PTZ-kindling. The cortical cholinergic system is affected to a much smaller extent. The neuropeptide changes are not persistent, as is the lowered seizure threshold, so they are probably not involved in the maintainance of the latter.
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PMID:Somatostatin, neuropeptide Y, GABA and cholinergic enzymes in brain of pentylenetetrazol-kindled rats. 257 17

Wistar rats were injected with a convulsant doze of pentylenetetrazol (PTZ) (50 mg/kg, i.p.). Somatostatin-like immunoreactivity (SLI) and 125I-Tyr11-somatostatin binding were measured in various brain areas immediately after PTZ injection, after the first head twitches, and 15 minutes, 1 h, 4 h, and 24 h after generalized tonic-clonic convulsions. SLI tended to decrease in the striatum (p less than 0.02), frontal cortex, hippocampus, and hypothalamus 1 hour after convulsion. Specific somatostatin binding remained stable. According to our results, somatostatin is not connected to initiation or spread of seizure but may play some role in depressing seizures.
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PMID:Somatostatin-like immunoreactivity and somatostatin receptor binding in rat brain before and after pentylenetetrazol-induced convulsion. 286 41

Neuropeptides represent a new class of compounds with important implications for the understanding of the mechanisms and treatment of epileptic disorders. Several systems of peptide modulators--in particular the opioid-like peptides, vasopressin, somatostatin, thyrotropin-releasing hormone (TRH) and ACTH--have partially demonstrated endogenous roles in some forms of epilepsy. Seizures and stressful situations may release endogenous opioid peptides and mediate postictal depression and postictal seizure refractoriness. Vasopressin is believed to increase susceptibility to convulsions and may be involved in the pathogenesis of febrile convulsions. Derangements in TRH regulation may lower thresholds for seizure expression by regulating arousal systems; however, some TRH analogs have proven to be effective anticonvulsants. Long-term alterations in somatostatin regulation could be components of focal epilepsies. ACTH is particularly useful in the treatment of infantile spasms. Pharmacological effects of these and other peptides have potentials for defining new classes of anticonvulsants. Cholecystokinin (CCK) and its analogs, the opioid peptides beta-endorphin and FK33824, TRH analogs, and several dipeptides exhibit potent anticonvulsant properties in chemical, electroshock, and genetic model screens. Convulsant actions of CRF, somatostatin, TRH, vasopressin, and high doses of endorphin or enkephalins may provide new tools to study regulatory mechanisms of cerebral excitability. The enkephalin epileptogenic effect is being developed as a predictive tool for new anti-petit mal anticonvulsants. Advances in molecular biology have identified the genes of particular peptide families. A concept has developed that the large propeptide precursors, coded by these genes, whose processing leads to functional peptide formation and release, regulate peptidergic humoral responses to external stimuli. This idea may have particular application in the understanding of the genetic basis of some seizure states. Techniques for amplification of mRNA expression have identified specific neuronal proteins and peptides. Knowledge of protein and propeptide structural cleavage sites has suggested previously unknown candidates for modular systems in epileptic states. Technological advances in automated peptide sequencing and synthesis have allowed the development of metabolically resistant analogs and antagonist peptides. The anticonvulsant potencies of CCK, TRH, and opioid peptides have been defined more clearly with these methods.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Neuropeptides: anticonvulsant and convulsant mechanisms in epileptic model systems and in humans. 287 23

Somatostatin and gamma-aminobutyric acid (GABA) concentrations were evaluated in the brain of kindled rats treated chronically with carbamazepine and valproic acid. Kindled seizures were almost completely blocked by treatment with carbamazepine, whereas the effect of valproic acid was partial, suppressing only generalized seizures. The duration of after-discharge in amygdala was suppressed by carbamazepine not by valproic acid. Carbamazepine induced a decrease in immunoreactive somatostatin concentration and an increase in GABA concentration in the temporal cortex of kindled rats. Valproic acid induced only an increase in GABA concentration. The results suggest that somatostatin may be associated with the suppression of focal seizure in amygdala and GABA may have a role in the suppression of generalized seizures.
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PMID:Effects of carbamazepine and valproic acid on brain immunoreactive somatostatin and gamma-aminobutyric acid in amygdaloid-kindled rats. 287 90

The occurrence of seizure activity in human temporal lobe epilepsy or status epilepticus is often associated with a characteristic pattern of cell loss in the hippocampus. An experimental model that replicates this pattern of damage in normal animals by electrical stimulation of the afferent pathway to the hippocampus was developed to study changes in structure and function that occur as a result of repetitive seizures. Hippocampal granule cell seizure activity caused a persistent loss of recurrent inhibition and irreversibly damaged adjacent interneurons. Immunocytochemical staining revealed unexpectedly that gamma-aminobutyric acid (GABA)-containing neurons, thought to mediate inhibition in this region and predicted to be damaged by seizures, had survived. In contrast, there was a nearly complete loss of adjacent somatostatin-containing interneurons and mossy cells that may normally activate inhibitory neurons. These results suggest that the seizure-induced loss of a basket cell-activating system, rather than a loss of inhibitory basket cells themselves, may cause disinhibition and thereby play a role in the pathophysiology and pathology of the epileptic state.
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PMID:Decreased hippocampal inhibition and a selective loss of interneurons in experimental epilepsy. 287 52

Somatostatin is a neuropeptide that in several experimental models of epilepsy has been suggested to modulate epileptic activity. The purpose of the present study was to investigate the role of somatostatin in seizure phenomena. We measured the somatostatin-like immunoreactivity (SLI) by radioimmunoassay of the cisternal CSF of rats. A polyethylene cannula had before-hand been inserted into the cisterna magna. Thereafter seizures were induced by pentylenetetrazol (PTZ). The nonconvulsive group of rats received a single subconvulsive dose of PTZ (30 mg/kg, i.p.). This group of rats exhibited only clonic jerks but not generalized clonic-tonic convulsion (GC). The CSF samples were taken 2 and 10 minutes after the jerks began. The convulsive group of rats received a single convulsive dose of PTZ (50 mg/kg, i.p.), and each of those animals had GC. From those rats the CSF samples were collected 5, 30, and 60 minutes and 4 and 24 h after the GC began. The values were compared with the SLI levels in controls, from which CSF was collected 10 minutes after injection of 0.9% NaCl. In the convulsion group the SLI levels increased 241% (p less than 0.01) five minutes after GC and returned to control level in 30 minutes. In the nonconvulsion group, where the rats expressed only jerks but not GC, SLI levels remained constant. These data suggest that somatostatin is released into CSF after the generalized clonic-tonic phase of the PTZ-induced convulsion.
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PMID:Effect of pentylenetetrazol-induced convulsions on somatostatin-like immunoreactivity in rat cerebrospinal fluid. 288 40

The origin of afferent somatostatin-containing fibers terminating in medial and ventral parts of the striatum has been investigated by performing various neurochemical and surgical lesions in the rat. Lesions of the anterior hypothalamus, amygdala, and the hippocampal commissure as well as lesions with 6-hydroxydopamine and 5,7-dihydroxytryptamine failed to decrease striatal somatostatin levels. However, thermal coagulation of the globus pallidus or knife-cut lesions performed ventrally to the striatum resulted in significant decreases in striatal somatostatin content. Analysis of the topographical distribution of somatostatin within the striatum after thermal lesions of the globus pallidus as well as after kainic acid-induced seizures revealed a preferential loss of the peptide in medial and ventral portions of the striatum, the site of terminating afferent somatostatin nerve fibers. The data suggest that the striatal afferent somatostatin-containing neurons may originate in the area of the globus pallidus.
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PMID:Evidence for somatostatin-containing fibers projecting from the pallidal complex to the striatum of the rat. 288 60

The role of the neuropeptide somatostatin in limbic seizures was studied using electrical stimulation of the hippocampus in kindled rats. Cysteamine, an agent which selectively and reversibly depletes brain somatostatin stores, had a biphasic action. An early proconvulsant effect was seen within a few hours, consisting of prolonged electrographic seizures in the hippocampus and more severe behavioral convulsions. A later anticonvulsant effect, maximal at 1 to 2 days and dissipating within a week, was manifested by less intense behavioral convulsions without change in the duration of electrical seizure activity. Both effects were dose-dependent. No change in afterdischarge thresholds was detected at any time after the administration of cysteamine. Intraventricular administration of somatostatin to animals with behavioral seizures attenuated by cysteamine treatment restored the responses to precysteamine levels. We conclude that somatostatin facilitates the spread of seizures over limbic circuits from a region of focal seizure initiation.
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PMID:Somatostatin augments the spread of limbic seizures from the hippocampus. 288 25

The anticonvulsant action of the new anticonvulsant drug gamma-vinyl-GABA (GVG) is obviously mediated by elevation of the concentration of GABA in the brain. The effect of GVG administration on other transmitter systems is not fully known in humans. We studied the possible interactions of GVG administration with peptidergic systems. Included in this study were 67 patients with complex partial epilepsy (CPS). The first CSF sample was taken before GVG administration. The second CSF sample was taken after 3 months of GVG treatment (3 g/day). Thereafter half of the responders (50% decrease in seizure frequency or clear improvement in global performance) received 3 g/day and the other half received 1.5 g/day for the next three months, after which the third CSF sample was taken. Somatostatin (SLI), beta-endorphin (beta-EP), and prolactin (PROL) levels in CSF were measured by radioimmunoassay. Total GABA (tGABA) and GVG levels in CSF were measured by high performance liquid chromatography. After 3 months of GVG treatment there was a slight increase in the beta-EP (p = 0.027, Student's paired t-test), which was not found after 6 months of GVG administration. Both SLI and PROL were stable during the study. Peptide levels were not connected to the clinical response to GVG, GVG dosage, or to tGABA levels in the CSF. In conclusion, the elevation of GABA levels in the brain during GVG treatment apparently does not induce long-term interactions with the peptidergic systems studied.
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PMID:Somatostatin, beta-endorphin, and prolactin levels in human cerebrospinal fluid during the gamma-vinyl-GABA treatment of patients with complex partial epilepsy. 288 76

The possible role of different peptidergic systems in the postictal stage of human epilepsy was studied by measuring beta-endorphin, somatostatin, and prolactin levels by radioimmunoassay of cerebrospinal fluid (CSF) from nine epileptic patients. The first sample was taken within 2 hours after generalised tonic-clonic convulsion, and the second sample was obtained interictally after 1-4 days without any kind of clinically observable seizures. beta-endorphin was elevated postictally (p = 0.044) compared with interictal levels. SLI and PROL were similar in both samples. The present study suggests that in humans beta-endorphin is released into CSF during generalised seizures. This may indicate that neurons containing beta-endorphin are activated during a seizure.
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PMID:Beta-endorphin, somatostatin, and prolactin levels in cerebrospinal fluid of epileptic patients after generalised convulsion. 289 Jul 16


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