Preconditioning with toll-like receptor agonists attenuates seizure activity and neuronal hyperexcitability in the pilocarpine rat model of epilepsy.

Neuroinflammation plays an important role in epileptic disorders. Toll-like receptors (TLRs) are the key signal transduction tools by which neuroinflammation may promote epileptogenesis. Depending on the stimulus nature, TLRs may engage a distinct signaling pathway. We examined the impact of early minor activation of TLR4 and TLR2 on the severity of seizure in the pilocarpine rat model of temporal lobe epilepsy (TLE). One µg of Lipopolysaccharides (LPS), Monophosphoryl lipid A (MPL), Pam3Cysor or vehicles were microinjected into the right lateral ventricle of the male Wistar rats. 24 h later, seizures were induced by intraperitoneal injection of pilocarpine, and seizure-related behaviors were monitored. 24 h after seizure induction, the hippocampal level of pro/anti-inflammatory mediators and electrophysiological properties of the dentate gyrus (DG) granular cells were investigated by western blot and whole cell patch clamp techniques, respectively. Pretreatment with TLR ligands resulted in decreased seizure severity, lower hippocampal pro-inflammatory (IL-1ß and IL-6) cytokines and higher anti-inflammatory (IL-10 and TGF- ß) mediators in the pilocarpine-treated rats. Pilocarpine induced profound hyperexcitability in the DG granule cells accompanied by potentiated excitatory postsynaptic currents (EPSCs) and dampened inhibitory postsynaptic currents (IPSCs), in contrast to the control group. However, pretreatment with TLR ligands preserved almost normal excitability and synaptic transmission against the pilocarpine. In conclusion, early activation of TLR4 and TLR2, probably through preserving normal hippocampal cytokine profile and neuronal function attenuates seizure severity in the rat model of TLE.

Calcium Channel Blockade Ameliorates Endoplasmic Reticulum Stress in the Hippocampus Induced by Amyloidopathy in the Entorhinal Cortex.

Entorhinal cortex (EC) is one of the first cerebral regions affected in Alzheimer's disease (AD). The pathology propagates to neighboring cerebral regions through a prion-like mechanism. In AD, intracellular calcium dyshomeostasis is associated with endoplasmic reticulum (ER) stress. This study was designed to examine hippocampal ER stress following EC amyloidopathy. Aß1-42 was bilaterally microinjected into the EC under stereotaxic surgery. Rats were daily treated with 30 µg of isradipine, nimodipine, or placebo over one week. Passive avoidance and novel object recognition (NOR) tasks were performed using shuttle box and NOR test, respectively. GRP78/BiP and CHOP levels were measured in the hippocampal dentate gyrus (DG) by western blot technique. The glutathione (GSH) level and PDI activity were also assessed in the hippocampus by colorimetric spectrophotometer. Aß treated group developed passive avoidance and novel recognition memory deficit compared to the control group. However, treatment with calcium channel blockers reversed the impairment. BiP and CHOP level increased in the hippocampus following amyloidopathy in the EC. PDI activity and GSH level in the hippocampus decreased in the Aß treated group, but calcium channel blockers restored them toward the control level. In conclusion, memory impairment due to EC amyloidopathy is associated with ER stress related bio-molecular changes in the hippocampus, and treatment with L-type calcium channel blockers may prevent the changes and ultimately improve cognitive performance.

Resveratrol Protects Purkinje Neurons and Restores Muscle Activity in Rat Model of Cerebellar Ataxia.

Cerebellar ataxia (CA) is regarded as a miscellaneous cluster of brain disorders related to the cerebellum. Resveratrol is a naturally occurring polyphenolic compound. Previous reports suggest that resveratrol confers neuroprotection in various animal models of brain damage. Indeed, we considered it invaluable to investigate whether a treatment with resveratrol has a therapeutic role against CA induced by 3-acetylpyridine (3-AP) in rats. In addition, no investigation has examined neuroprotective effect of resveratrol in rat model of CA. Initially, 3-AP administration generated CA rat models followed by intraperitoneal injection with resveratrol. Then, motor performance and muscle electromyography (EMG) activity were assessed. Moreover, the anti-apoptotic role of resveratrol in CA and its relationship to protection of Purkinje cells were explored. According to what we have found, resveratrol administration improved the muscle activity and movement coordination in 3-AP-lesioned rats. Also under resveratrol treatment, the total number of the Purkinje neurons increased whereas a reduction in apoptotic bodies was observed. In conclusion, post-treatment with resveratrol evidently ameliorated motor performance as well as muscle activity accompanied by a protection of Purkinje cells in ataxic rats.

Human Umbilical Cord Matrix Stem Cells Reverse Oxidative Stress-Induced Cell Death and Ameliorate Motor Function and Striatal Atrophy in Rat Model of Huntington Disease.

Huntington disease (HD) is an inherited disorder hallmarked by progressive deterioration of specific neurons, followed by movement and cognitive anomalies. Cell therapy approaches in neurodegenerative conditions have concentrated on the replenishment of lost/dying neurons with functional ones. Multipotent mesenchymal stem cells (MSCs) have been represented as a potential remedy for HD. In this study, we evaluated the in vitro and in vivo efficacy of umbilical cord matrix stem cells (UCMSCs) and their paracrine effect against oxidative stress with a specific focus on HD. To this end, UCMSCs were isolated, immunophenotypically characterized by the positive expression of MSC markers, and exhibited multilineage potentiality. Besides, synthesis of neurotrophic factors of GDNF and VEGF by UCMSC was confirmed. Initially, PC12 cells were exposed to superoxide in the presence of conditioned media (CM) collected from UCMSC (UCMSC-CM) and cell viability plus neuritogenesis were measured. Next, bilateral striatal transplantation of UCMSC in 3-nitropropionic acid (3-NP) lesioned rat models was conducted, and 1 month later, post-graft analysis was performed. According to our in vitro results, CM of UCMSC protected PC12 cells against oxidative stress and considerably enhanced cell viability and neurite outgrowth. On the other hand, transplanted UCMSC survived, decreased gliosis, and ameliorated motor coordination and muscle activity, along with an increase in striatal volume as well as in dendritic length of the striatum in HD rats. Collectively, our findings imply that UCMSCs provide an enriched platform by largely their paracrine factors, which downgrades the unfavorable effects of oxidative stress.