Fos expression in GABAergic cells and cells immunopositive for NMDA receptors in the inferior and superior colliculi following audiogenic seizures in rats

Abstract

Given the evidence that the inferior colliculus (IC) and superior colliculus (SC) seem to play key roles in connecting auditory pathways and seizure output pathways in the neuronal network for audiogenic seizures (AS) in rats, we examined Fos activation in GABAergic cells and cells immunopositive for glutamate N-methyl-D-aspartate (NMDA) receptors in the IC and SC following AS using the double-labeling procedure. Generalized tonic-clonic seizures (GTCS), which developed as an advanced form of AS in some of the susceptible rats, induced an increase in Fos expression in three IC substructures-the dorsal cortex of IC (DCIC), central nucleus of IC (CIC), and external cortex of IC (ECIC)-and in one SC substructure, the deep gray layer of SC (DpG). Compared with the rats showing GTCS, rats exhibiting wild running (WR) without proceeding to GTCS showed a different pattern of AS-induced Fos expression. The DpG in the WR animals showed no significant increase in the levels of Fos-like immunoreactivity. The degrees of Fos activation that occurred in GABAergic cells and cells immunopositive for NMDA receptors were similar in the DCIC, CIC, ECIC, and DpG following AS. These results suggest that Fos activation in the DpG is involved in the development from WR to GTCS in AS-susceptible rats. They also provide some evidence that some GABAergic neurons in the IC and SC and glutamatergic afferents (via NMDA receptors) to these structures are activated by AS.

The genetic audiogenic seizure hamster from Salamanca: The GASH:Sal

“…Fos immunoreactivity in the IC after the onset of an acute seizure has also been found in various rat [61,62,64] and mice [65,66] models with audiogenic susceptibility. Many studies have demonstrated a critical role for the IC at the onset of the AGS in various lines of susceptible animals [67][68][69][70][71][72][73][74][75][76].…”

“…Our data also showed significant overexpression of the c-fos gene in the PAG in the GASH:Sal hamsters, which is consistent with studies in other strains that have AGS (GEPR-9 rats [81], C57BL/6J mice, and DBA/2J mice [66]). This structure is considered to be involved in the onset of both the clonic phases of AGS [69,81,82] and the tonic-clonic [67] phases.…”

Efects of ethanol on electroencephalographic and behavioral signs of metaphit-induced audiogenic seizure

“…Similarly, metaphit affects numerous neurotransmitter systems and receptors, such as serotonergic (Nabeshima et al, 1989), dopaminergic, voltage-dependent sodium channels and sigma receptors (Wang et al,1987). Ishida et al (2002) demonstrated that audiogenic seizures induced by high-intensity sound stimulation in genetically susceptible mice and rats expressed typical and characteristic signs of epilepsy (running, clonus and tonus). In this model, convulsions were triggered by creating an imbalance between excitatory and inhibitory brain activities, mainly by increasing excitatory influences related to glutamate activity.…”

Anticonvulsant, but Not Antiepileptic, Action of Valproate on Audiogenic Seizures in Metaphit–treated Rats

“…Ishida et al 30 . demonstrated that audiogenic seizures induced by high‐intensity sound stimulation in genetically susceptible mice and rats expressed typical and characteristic signs of epilepsy (running, clonus and tonus).…”