Increased expression of phosphate-activated glutaminase in hippocampal neurons in human mesial temporal lobe epilepsy

The enzyme glutamine synthetase (GS), also referred to as glutamate ammonia ligase, is abundant in astrocytes and catalyzes the conversion of ammonia and glutamate to glutamine. Deficiency or dysfunction of astrocytic GS in discrete brain regions have been associated with several types of epilepsy, including medically-intractable mesial temporal lobe epilepsy (MTLE), neocortical epilepsies, and glioblastoma-associated epilepsy. Moreover, experimental inhibition or deletion of GS in the entorhinal-hippocampal territory of laboratory animals causes an MTLE-like syndrome characterized by spontaneous, recurrent hippocampal-onset seizures, loss of hippocampal neurons, and in some cases comorbid depressive-like features. The goal of this review is to summarize and discuss the possible roles of astroglial GS in the pathogenesis of epilepsy.

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Interleukin-1β plays a role in the pathogenesis of mesial temporal lobe epilepsy through the PI3K/Akt/mTOR signaling pathway in hippocampal neurons

Journal of Neuroimmunology ◽

10.1016/j.jneuroim.2015.04.003 ◽

2015 ◽

Vol 282 ◽

pp. 110-117 ◽

Cited By ~ 36

Author(s):

Zhaohua Xiao ◽

Jing Peng ◽

Lifen Yang ◽

Huimin Kong ◽

Fei Yin

Keyword(s):

Temporal Lobe Epilepsy ◽

Signaling Pathway ◽

Temporal Lobe ◽

Hippocampal Neurons ◽

Mesial Temporal Lobe Epilepsy ◽

Mtor Signaling ◽

Interleukin 1Β ◽

Mtor Signaling Pathway ◽

Mesial Temporal Lobe

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Do Hippocampal Neurons Really Count for Comorbid Depression in Patients With Mesial Temporal Lobe Epilepsy and Hippocampal Sclerosis? A Histopathological Study

Frontiers in Integrative Neuroscience ◽

10.3389/fnint.2021.747237 ◽

2021 ◽

Vol 15 ◽

Author(s):

Nathália Stela Visoná de Figueiredo ◽

Anaclara Prada Jardim ◽

Lenon Mazetto ◽

Jeana Torres Corso Duarte ◽

Sandra Mara Comper ◽

...

Keyword(s):

Temporal Lobe Epilepsy ◽

Temporal Lobe ◽

Hippocampal Neurons ◽

Hippocampal Sclerosis ◽

Mesial Temporal Lobe Epilepsy ◽

Histopathological Study ◽

Comorbid Depression ◽

Neuronal Density ◽

Mesial Temporal Lobe ◽

Patients With Epilepsy

Depression is the most frequent psychiatric comorbidity seen in mesial temporal lobe epilepsy (MTLE) patients with hippocampal sclerosis (HS). Moreover, the HS is the most frequent pathological hallmark in MTLE-HS. Although there is a well-documented hippocampal volumetric reduction in imaging studies of patients with major depressive disorder, in epilepsy with comorbid depression, the true role of the hippocampus is not entirely understood. This study aimed to verify if patients with unilateral MTLE-HS and the co-occurrence of depression have differences in neuronal density of the hippocampal sectors CA1–CA4. For this purpose, we used a histopathological approach. This was a pioneering study with patients having both clinical disorders. However, we found no difference in hippocampal neuronal density when depression co-occurs in patients with epilepsy. In this series, CA1 had the lowest counting in both groups, and HS ILAE Type 1 was the most prevalent. More studies using histological assessments are needed to clarify the physiopathology of depression in MTLE-HS.

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