Anticonvulsant effects of sevoflurane on amygdaloid kindling and bicuculline-induced seizures in cats: comparison with isoflurane and halothane

Murao, Kohei; Shingu, Koh; Miyamoto, Etsuko; Ikeda, Shunichiro; Nakao, Shinichi; Masuzawa, Munehiro; Yamada, Makiko

doi:10.1007/s540-002-8092-0

Cited by 13 publications

(8 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Anesthesia was employed as a positive control for seizure suppression (Delgado-Escueta et al,1982, 1983; Ropper et al, 1986; Murao et al, 2002). Eleven epileptic rpFPI rats were recorded for 72-hr six weeks after injury.…”

Section: Resultsmentioning

confidence: 99%

ECoG studies of valproate, carbamazepine and halothane in frontal-lobe epilepsy induced by head injury in the rat

Eastman

Verley

Fender

et al. 2010

Experimental Neurology

View full text Add to dashboard Cite

The use of electrocorticography (ECoG) with etiologically realistic epilepsy models promises to facilitate the discovery of better anti-epileptic drugs (AEDs). However, this novel approach is labor intensive, and must be optimized. To this end, we employed rostral parasaggital fluid percussion injury (rpFPI) in the adolescent rat, which closely replicates human contusive closed head injury and results in posttraumatic epilepsy (PTE). We systematically examined variables affecting the power to detect antiepileptic effects by ECoG and used a non-parametric bootstrap strategy to test several different statistics, study designs, statistical tests, and impact of nonresponders. We found that logarithmically transformed data acquired in repeated-measures experiments provided the greatest statistical power to detect decreases in seizure frequencies of pre-clinical interest with just 8 subjects and with up to ~40% non-responders. We then used this optimized design to study the antiepileptic effects of acute exposure to halothane, and chronic (1 week) exposures to carbamazepine (CBZ) and valproate (VPA) one month post-injury. While CBZ was ineffective in all animals, VPA induced, during treatment, a progressive decrease in seizure frequency in animals primarily suffering from non-spreading neocortical seizures, but was ineffective in animals with high frequency of spreading seizures. Halothane powerfully blocked all seizure activity. The data show that rpFPI and chronic ECoG can conveniently be employed for evaluation of AEDs, suggest that VPA may be more effective than CBZ to treat some forms of PTE and support the theory that pharmacoresistance may depend on the severity of epilepsy. The data also demonstrate the utility of chronic exposures to experimental drugs in preclinical studies and highlight the need for greater attention to etiology in clinical studies of AEDs.

show abstract

Section: Resultsmentioning

confidence: 99%

ECoG studies of valproate, carbamazepine and halothane in frontal-lobe epilepsy induced by head injury in the rat

Eastman

Verley

Fender

et al. 2010

Experimental Neurology

View full text Add to dashboard Cite

show abstract

“…Because these drugs arrive rapidly in the brain at effective concentrations following systemic administration ( Yonekawa et al, 1980 ; Ramzan and Levy, 1985 ), it is unlikely that the progression of interneuron firing changes resulted from gradual accumulation of chemoconvulsants in neural tissue. Our experiments were largely conducted under anesthesia, which could potentially prolong the preictal period and reduce seizure activity ( Murao et al, 2002 ; Fang and Wang, 2015 ; Grover et al, 2016 ). However, the light anesthesia we used allowed normal spontaneous hippocampal firing patterns to be maintained and promoted short ictal onset delays similar to those in awake animals.…”

Section: Discussionmentioning

confidence: 99%

Altered hippocampal interneuron activity precedes ictal onset

Miri

Vinck

Pant

et al. 2018

eLife

View full text Add to dashboard Cite

Although failure of GABAergic inhibition is a commonly hypothesized mechanism underlying seizure disorders, the series of events that precipitate a rapid shift from healthy to ictal activity remain unclear. Furthermore, the diversity of inhibitory interneuron populations poses a challenge for understanding local circuit interactions during seizure initiation. Using a combined optogenetic and electrophysiological approach, we examined the activity of identified mouse hippocampal interneuron classes during chemoconvulsant seizure induction in vivo. Surprisingly, synaptic inhibition from parvalbumin- (PV) and somatostatin-expressing (SST) interneurons remained intact throughout the preictal period and early ictal phase. However, these two sources of inhibition exhibited cell-type-specific differences in their preictal firing patterns and sensitivity to input. Our findings suggest that the onset of ictal activity is not associated with loss of firing by these interneurons or a failure of synaptic inhibition but is instead linked with disruptions of the respective roles these interneurons play in the hippocampal circuit.

show abstract

“…Isoflurane has well-documented anticonvulsant properties and in experimental models is probably the most potent anticonvulsant of the volatile agents [1,37]. Isoflurane is typically the volatile utilised in the clinical setting when the first choice anticonvulsants such as midazolam and/or phenytoin fail to control seizure activity.…”

Section: Discussionmentioning

confidence: 99%

Enhancement of Cortical GABAergic Function does not Account for the Anticonvulsant Effects of Midazolam, Isoflurane or Etomidate~!2009-11-19~!2010-05-23~!2010-07-29~!

Voss¹,

Sleigh

2010

TOATJ

View full text Add to dashboard Cite

Background: Enhancement of cerebrocortical GABAergic inhibition is postulated as the main mechanism by which anesthetics inhibit seizures; however this has not been directly tested under controlled conditions. In this study we utilized the isolated cerebral cortex slice preparation and tested the anticonvulsant properties of three anesthetics with differing specificities for GABAergic activation and with various clinical and experimental anticonvulsant efficacy; midazolam, isoflurane and etomidate. Methods: Two interictal-like models were investigated; low-magnesium artificial cerebrospinal fluid (ACSF) and low dose (230nM) aconitine in low-magnesium ACSF. The former generates interictal-like events by facilitating NMDA activation and is well described in the cortical slice preparation; the latter generates a unique pattern of interictal-like activity by opening voltage-gated sodium channels. Results: We found that at anesthetic concentrations and above (15 M midazolam, 480 M isoflurane and 4 M etomidate), only isoflurane had an anticonvulsant effect. The isoflurane effect was seen as a reduction in event frequency in both models (56% reduction in low-magnesium and 26% reduction in aconitine, p<0.005 and p<0.05, respectively). Picrotoxin (100 M) was ineffective at blocking the isoflurane anticonvulsant effect (56% reduction in event frequency, p<0.01). Picrotoxin (100 M) and bicuculline (25 M) administered on their own increased event frequency (107% and 75%, respectively, p<0.005), indicating the GABAergic system was functional in the slice preparation. Conclusion: These results call into question the view that enhancement of cortical GABAergic function is the primary mechanism by which anesthetics suppress seizure activity.

show abstract

Anticonvulsant effects of sevoflurane on amygdaloid kindling and bicuculline-induced seizures in cats: comparison with isoflurane and halothane

Abstract: The anticonvulsant effects of sevoflurane were less potent than those of halothane in the amygdaloid kindling model and less potent than those of isoflurane in the bicuculline-induced seizure model.

Cited by 13 publications

References 24 publications

ECoG studies of valproate, carbamazepine and halothane in frontal-lobe epilepsy induced by head injury in the rat

ECoG studies of valproate, carbamazepine and halothane in frontal-lobe epilepsy induced by head injury in the rat

Altered hippocampal interneuron activity precedes ictal onset

Enhancement of Cortical GABAergic Function does not Account for the Anticonvulsant Effects of Midazolam, Isoflurane or Etomidate~!2009-11-19~!2010-05-23~!2010-07-29~!

Contact Info

Product

Resources

About