Effect of Midbrain and Pontine Tegmental Lesions on the Maximal Electroshock Seizure Pattern in Rats

Browning, Ronald A.; Turner, Fred J.; Simonton, Ronald L.; Bundman, Marsha C.

doi:10.1111/j.1528-1157.1981.tb04130.x

Cited by 62 publications

(27 citation statements)

References 12 publications

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“…One explanation is that mice administered 20 mg/kg KA had less mortality when ethosuximide was used (Fig. 1–4) because of a protective effect of ethosuximide on mortality by decreasing brainstem-associated seizures (Browning et al, 1981; Fromm, 1985; Mares et al, 1994). …”

Section: Resultsmentioning

confidence: 99%

“…Pretreatment with the anticonvulsant ethosuximide inhibits seizure activity in the brainstem (Mares et al, 1994), which is critical for the generation of the severe convulsive behaviors such as running and bouncing (Browning et al, 1981; Fromm, 1985). Therefore, we used ethosuximide pretreatment to optimize conditions for a study where forebrain networks were of interest – i.e., the location of adult-born neurons.…”

Section: Introductionmentioning

confidence: 99%

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Suppression of Adult Neurogenesis Increases the Acute Effects of Kainic Acid

Iyengar

LaFrancois

Friedman

et al. 2015

Experimental Neurology

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Adult neurogenesis, the generation of new neurons in the adult brain, occurs in the hippocampal dentate gyrus (DG) and the olfactory bulb (OB) of all mammals, but the functions of these new neurons are not entirely clear. Originally, adult-born neurons were considered to have excitatory effects on the DG network, but recent studies suggest a net inhibitory effect. Therefore, we hypothesized that selective removal of newborn neurons would lead to increased susceptibility to the effects of a convulsant. This hypothesis was tested by evaluating the response to the chemoconvulsant kainic acid (KA) in mice with reduced adult neurogenesis, produced either by focal X-irradiation of the DG, or by pharmacogenetic deletion of dividing radial glial precursors. In the first 4 hrs after KA administration, when mice have the most robust seizures, mice with reduced adult neurogenesis had more severe convulsive seizures, exhibited either as a decreased latency to the first convulsive seizure, greater number of convulsive seizures, or longer convulsive seizures. Nonconvulsive seizures did not appear to change or they decreased. Four-21 hrs after KA injection, mice with reduced adult neurogenesis showed more interictal spikes (IIS) and delayed seizures than controls. Effects were greater when the anticonvulsant ethosuximide was injected 30 min prior to KA administration; ethosuximide allows forebrain seizure activity to be more easily examined in mice by suppressing seizures dominated by the brainstem. These data support the hypothesis that reduction of adult-born neurons increases the susceptibility of the brain to effects of KA.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Suppression of Adult Neurogenesis Increases the Acute Effects of Kainic Acid

Iyengar

LaFrancois

Friedman

et al. 2015

Experimental Neurology

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“…Tonic hindlimb extension (THE) seizures, which are mediated by the brainstem, were used to assess hindbrain seizure thresholds (Browning, 1985;Browning, 1986;Browning, et al, 1981;Eells, et al, 2004). THE seizures begin as tonic forelimb extension, spread to hindlimb flexion, and terminate in full tonic hindlimb extension (180 degrees to the torso).…”

Section: Seizure Testingmentioning

confidence: 99%

Traumatic brain injury during development reduces minimal clonic seizure thresholds at maturity

et al. 2008

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Post-traumatic seizures affect 12 -35% of children after traumatic brain injury (TBI) and are associated with worse cognitive and functional outcome, even after adjustment for severity of injury. Unfortunately, experimental models of pediatric post-traumatic epilepsy are lacking, and pathogenesis remains poorly understood. We have applied a standard model of TBI in immature rats to determine the effect of TBI on electroconvulsive seizure thresholds later in life.Male rats underwent controlled cortical impact to left parietal cortex on post-natal day (PND) 16-18. Hindbrain, forebrain, and limbic seizure thresholds were assessed, respectively, by tonic hindlimb extension (THE), minimal clonic, and partial psychomotor seizure responses during adolescence and at maturity (PND 60 -63). Post-traumatic seizure thresholds were compared to those obtained in age-and litter-matched sham craniotomy and naïve controls.TBI during immaturity had no clear effect on THE seizure thresholds. In contrast, TBI lowered minimal clonic seizure thresholds at maturity (p < 0.05 vs. sham or naïve rats), but not during adolescence. Consequently, minimal clonic seizure thresholds increased with age for sham and naïve rats but remained similar for TBI rats during adolescence and at maturity. TBI also tended to lower partial psychomotor seizure thresholds, which were determined only during adolescence (p < 0.1 vs. naive).Controlled cortical impact causes both focal cortical injury at the site of impact and ipsilateral hippocampal neuronal death. Since minimal clonic seizures are mediated by the forebrain, partial psychomotor seizures by the limbic system, and THE seizures by the brainstem, the observed pattern of changes in post-traumatic seizure thresholds is not surprising. The apparent age-dependent effects of TBI, however, are unexpected and likely due to a combination of attenuated maturational increases

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“…Mechanical lesions of the midbrain and pontine tegmental areas have been shown to antagonize experimentally induced tonic seizures and to retard the development of generalized seizures resulting from kindling of the amygdala, supposedly from the interruption of dopamine destined for the amygdala and produced in the midbrain [16]. Current neuroanatomical studies suggest a medial to lateral anatomical separation of gustatory and cardiopulmonary inputs in the amygdala [6].…”

Section: Discussionmentioning

confidence: 99%

The Effectiveness of Hering’s Nerve Stimulation in Controlling Penicillin-Induced Seizures in the Rat Is Dependent on the Amygdala

Tubbs¹,

Patwardhan²,

Oakes³

et al. 2002

Pediatr Neurosurg

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Objective: This study tests the hypothesis that the ability of Hering’s nerve stimulation (HNS) to blunt seizure activity is dependent on the availability of dopamine in the amygdala. Methods: In 10 rats, Hering’s nerve (HN) on the right side was isolated and placed on an electrode and penicillin was locally placed on each rat’s left frontoparietal region to induce seizures. After the initiation of seizures, HN was stimulated. After the recurrence of seizure activity, the left basolateral amygdala was injected with 1.0 µl of normal saline, dopamine, haloperidol or 1% lidocaine in sequential tests. HN was stimulated after each injection and the latency and amplitude of the seizure activity were assessed. Results: Focal cortical penicillin induced seizures that resulted in tonic-clonic movement of the limbs and face that lasted 35–45 min. Tonic-clonic movements of the limbs and face of similar latency and amplitude were induced by repeated reapplication of penicillin in untreated rats. HNS decreased seizure activity, but infusion of haloperidol or lidocaine into the basolateral amygdala blocked this antiseizure effect of HNS. In contrast, infusion of saline or dopamine had no effect on the ability of HNS to blunt seizure activity. None of the amygdala injections altered the latency or amplitude of seizure activity. Conclusion: These results demonstrate that the ability of HNS to blunt seizure activity in the rat is dependent on an intact dopamine system in the basolateral amygdala. These data will hopefully be useful in furthering our understanding of the circuitry that allows peripheral nerve stimulation to alter seizure activity.

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Effect of Midbrain and Pontine Tegmental Lesions on the Maximal Electroshock Seizure Pattern in Rats

Cited by 62 publications

References 12 publications

Suppression of Adult Neurogenesis Increases the Acute Effects of Kainic Acid

Suppression of Adult Neurogenesis Increases the Acute Effects of Kainic Acid

Traumatic brain injury during development reduces minimal clonic seizure thresholds at maturity

The Effectiveness of Hering’s Nerve Stimulation in Controlling Penicillin-Induced Seizures in the Rat Is Dependent on the Amygdala

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