Patterns of hippocampal neuronal loss and axon reorganization of the dentate gyrus in the mouse pilocarpine model of temporal lobe epilepsy

2009 ◽  
Vol 87 (5) ◽  
pp. 1135-1149 ◽  
Author(s):  
Si Zhang ◽  
Sanjay Khanna ◽  
Feng Ru Tang
Keyword(s):  
Temporal Lobe Epilepsy ◽  
Dentate Gyrus ◽  
Temporal Lobe ◽  
Neuronal Loss ◽  
Pilocarpine Model

Spontaneous Excitatory Currents and κ-Opioid Receptor Inhibition in Dentate Gyrus Are Increased in the Rat Pilocarpine Model of Temporal Lobe Epilepsy

1997 ◽  
Vol 78 (4) ◽  
pp. 1860-1868 ◽  
Author(s):  
Michele L. Simmons ◽  
Gregory W. Terman ◽  
Charles Chavkin
Keyword(s):  
Temporal Lobe Epilepsy ◽  
Dentate Gyrus ◽  
Opioid Receptor ◽  
Temporal Lobe ◽  
Mossy Fiber ◽  
Perforant Path ◽  
Mossy Fiber Sprouting ◽  
Receptor Inhibition ◽  
Excitatory Activity ◽  
Pilocarpine Model

Simmons, Michele L., Gregory W. Terman, and Charles Chavkin. Spontaneous excitatory currents and κ-opioid receptor inhibition in dentate gyrus are increased in the rat pilocarpine model of temporal lobe epilepsy. J. Neurophysiol. 78: 1860–1868, 1997. Temporal lobe epilepsy is associated with a characteristic pattern of synaptic reorganization in the hippocampal formation, consisting of neuronal loss and aberrant growth of mossy fiber collaterals into the dentate gyrus inner molecular layer. We have used the rat pilocarpine model of temporal lobe epilepsy to study the functional consequences of mossy fiber sprouting on excitatory activity and κ-opioid receptor-mediated inhibition. Using the whole cell voltage-clamp technique, we found that abnormal excitatory activity was evident in granule cells of the dentate gyrus from pilocarpine-treated rats. The frequency of spontaneous excitatory postsynaptic currents (EPSCs) was increased greatly in cells from tissue in which significant mossy fiber sprouting had developed. In the presence of bicuculline, giant spontaneous EPSCs, with large amplitudes and long durations, were seen only in association with mossy fiber sprouting. Giant EPSCs also could be evoked by low-intensity stimulation of the perforant path. Mossy fibers release not only excitatory amino acids, but also opioid peptides. κ-Opioid receptor-mediated inhibition in normal Sprague-Dawley rats was seen only in hippocampal sections from the ventral pole. In pilocarpine-treated rats, however, kappa receptor-mediated effects were seen in both ventral and more dorsal sections. Thus in this model of temporal lobe epilepsy, several types of abnormal excitatory activity were observed, thereby supporting the idea that mossy fiber sprouting leads to recurrent excitatory connections. At the same time, inhibition of excitatory activity by κ-opioid receptors was increased, perhaps representing an endogenous anticonvulsant mechanism.

scholarly journals Metabolism is Normal in Astrocytes in Chronically Epileptic Rats: A 13C NMR Study of Neuronal—Glial Interactions in a Model of Temporal Lobe Epilepsy

2005 ◽  
Vol 25 (10) ◽  
pp. 1254-1264 ◽  
Author(s):  
Torun M Melø ◽  
Astrid Nehlig ◽  
Ursula Sonnewald
Keyword(s):  
Cerebral Cortex ◽  
Temporal Lobe Epilepsy ◽  
Temporal Lobe ◽  
Hippocampal Formation ◽  
Neuronal Loss ◽  
Adenosine Diphosphate ◽  
Resonance Spectroscopy ◽  
Metabolic Disturbances ◽  
Nmr Study ◽  
Pilocarpine Model

The aim of the present work was to study potential disturbances in metabolism and interactions between neurons and glia in the lithium-pilocarpine model of temporal lobe epilepsy. Rats chronically epileptic for 1 month received [1-13C]glucose, a substrate for neurons and astrocytes, and [1,2-13C]acetate, a substrate for astrocytes only. Analyses of extracts from cerebral cortex, cerebellum, and hippocampal formation (hippocampus, amygdala, entorhinal, and piriform cortices) were performed using 13C and 1H nuclear magnetic resonance spectroscopy and HPLC. In the hippocampal formation of epileptic rats, levels of glutamate, aspartate, N-acetyl aspartate, adenosine triphosphate plus adenosine diphosphate and glutathione were decreased. In all regions studied, labeling from [1,2-13C]acetate was similar in control and epileptic rats, indicating normal astrocytic metabolism. However, labeling of glutamate, GABA, aspartate, and alanine from [1-13C]glucose was decreased in all areas possibly reflecting neuronal loss. The labeling of glutamine from [1-13C]glucose was decreased in cerebral cortex and cerebellum and unchanged in hippocampal formation. In conclusion, no changes were detected in glial—neuronal interactions in the hippocampal formation while in cortex and cerebellum the flow of glutamate to astrocytes was decreased, indicating a disturbed glutamate—glutamine cycle. This is, to our knowledge, the first study showing that metabolic disturbances are confined to neurons inside the epileptic circuit.

Survival of mossy cells of the hippocampal dentate gyrus in humans with mesial temporal lobe epilepsy

2009 ◽  
Vol 111 (6) ◽  
pp. 1237-1247 ◽  
Author(s):  
László Seress ◽  
Hajnalka Ábrahám ◽  
Zsolt Horváth ◽  
Tamás Dóczi ◽  
József Janszky ◽  
...  
Keyword(s):  
Temporal Lobe Epilepsy ◽  
Dentate Gyrus ◽  
Temporal Lobe ◽  
Pyramidal Neurons ◽  
Hippocampal Sclerosis ◽  
Mesial Temporal Lobe Epilepsy ◽  
Drug Resistant ◽  
Hippocampal Dentate Gyrus ◽  
Mossy Cells ◽  
Mesial Temporal Lobe

Object Hippocampal sclerosis can be identified in most patients with mesial temporal lobe epilepsy (TLE). Surgical removal of the sclerotic hippocampus is widely performed to treat patients with drug-resistant mesial TLE. In general, both epilepsy-prone and epilepsy-resistant neurons are believed to be in the hippocampal formation. The hilar mossy cells of the hippocampal dentate gyrus are usually considered one of the most vulnerable types of neurons. The aim of this study was to clarify the fate of mossy cells in the hippocampus in epileptic humans. Methods Of the 19 patients included in this study, 15 underwent temporal lobe resection because of drug-resistant TLE. Four patients were used as controls because they harbored tumors that had not invaded the hippocampus and they had experienced no seizures. Histological evaluation of resected hippocampal tissues was performed using immunohistochemistry. Results Mossy cells were identified in the control as well as the epileptic hippocampi by using cocaine- and amphetamine-regulated transcript peptide immunohistochemistry. In most cases the number of mossy cells was reduced and thorny excrescences were smaller in the epileptic hippocampi than in controls; however, there was a significant loss of pyramidal cells and a partial loss of granule cells in the same epileptic hippocampi in which mossy cell loss was apparent. The loss of mossy cells could be correlated with the extent of hippocampal sclerosis, patient age at seizure onset, duration of epilepsy, and frequency of seizures. Conclusions In many cases large numbers of mossy cells were present in the hilus of the dentate gyrus when most pyramidal neurons of the CA1 and CA3 areas of the Ammon's horn were lost, suggesting that mossy cells may not be more vulnerable to epileptic seizures than the hippocampal pyramidal neurons.

scholarly journals Hyperpolarization-activated cation current Ih of dentate gyrus granule cells is upregulated in human and rat temporal lobe epilepsy

2012 ◽  
Vol 420 (1) ◽  
pp. 156-160 ◽  
Author(s):  
Rainer Surges ◽  
Maria Kukley ◽  
Amy Brewster ◽  
Christiane Rüschenschmidt ◽  
Johannes Schramm ◽  
...  
Keyword(s):  
Temporal Lobe Epilepsy ◽  
Dentate Gyrus ◽  
Temporal Lobe ◽  
Granule Cells ◽  
Cation Current
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