Targeting oxidative stress improves disease outcomes in a rat model of acquired epilepsy.

Epilepsy therapy is based on antiseizure drugs that treat the symptom, seizures, rather than the disease and are ineffective in up to 30% of patients. There are no treatments for modifying the disease-preventing seizure onset, reducing severity or improving prognosis. Among the potential molecular targets for attaining these unmet therapeutic needs, we focused on oxidative stress since it is a pathophysiological process commonly occurring in experimental epileptogenesis and observed in human epilepsy. Using a rat model of acquired epilepsy induced by electrical status epilepticus, we show that oxidative stress occurs in both neurons and astrocytes during epileptogenesis, as assessed by measuring biochemical and histological markers. This evidence was validated in the hippocampus of humans who died following status epilepticus. Oxidative stress was reduced in animals undergoing epileptogenesis by a transient treatment with N-acetylcysteine and sulforaphane, which act to increase glutathione levels through complementary mechanisms. These antioxidant drugs are already used in humans for other therapeutic indications. This drug combination transiently administered for 2 weeks during epileptogenesis inhibited oxidative stress more efficiently than either drug alone. The drug combination significantly delayed the onset of epilepsy, blocked disease progression between 2 and 5 months post-status epilepticus and drastically reduced the frequency of spontaneous seizures measured at 5 months without modifying the average seizure duration or the incidence of epilepsy in animals. Treatment also decreased hippocampal neuron loss and rescued cognitive deficits. Oxidative stress during epileptogenesis was associated with de novo brain and blood generation of disulfide high mobility group box 1 (HMGB1), a neuroinflammatory molecule implicated in seizure mechanisms. Drug-induced reduction of oxidative stress prevented disulfide HMGB1 generation, thus highlighting a potential novel mechanism contributing to therapeutic effects. Our data show that targeting oxidative stress with clinically used drugs for a limited time window starting early after injury significantly improves long-term disease outcomes. This intervention may be considered for patients exposed to potential epileptogenic insults.

Low dietary protein content alleviates motor symptoms in mice with mutant dynactin/dynein-mediated neurodegeneration.

Mutations in components of the molecular motor dynein/dynactin lead to neurodegenerative diseases of the motor system or atypical parkinsonism. These mutations are associated with prominent accumulation of vesicles involved in autophagy and lysosomal pathways, and with protein inclusions. Whether alleviating these defects would affect motor symptoms remain unknown. Here, we show that a mouse model expressing low levels of disease linked-G59S mutant dynactin p150(Glued) develops motor dysfunction >8 months before loss of motor neurons or dopaminergic degeneration is observed. Abnormal accumulation of autophagosomes and protein inclusions were efficiently corrected by lowering dietary protein content, and this was associated with transcriptional upregulations of key players in autophagy. Most importantly this dietary modification partially rescued overall neurological symptoms in these mice after onset. Similar observations were made in another mouse strain carrying a point mutation in the dynein heavy chain gene. Collectively, our data suggest that stimulating the autophagy/lysosomal system through appropriate nutritional intervention has significant beneficial effects on motor symptoms of dynein/dynactin diseases even after symptom onset.

Fish oil provides robust and sustained memory recovery after cerebral ischemia: influence of treatment regimen.

We previously reported that long-term treatment with fish oil (FO) facilitates memory recovery after transient, global cerebral ischemia (TGCI), despite the presence of severe hippocampal damage. The present study tested whether this antiamnesic effect resulted from an action of FO on behavioral performance itself, or whether it resulted from an anti-ischemic action. Different treatment regimens were used that were distinguished from each other by their initiation or duration with regard to the onset of TGCI and memory assessment. Naive rats were trained in an eight-arm radial maze, subjected to TGCI (4-VO model, 15 min), and tested for memory performance up to 6 weeks after TGCI. Fish oil (docosahexaenoic acid, 300 mg/kg/day) was given orally according to one of the following regimens: regimen 1 (from 3 days prior to ischemia until 4 weeks post-ischemia), regimen 2 (from 3 days prior to ischemia until 1 week post-ischemia), and regimen 3 (from week 2 to week 5 post-ischemia). When administered according to regimens 1 and 2, FO abolished amnesia completely. This effect persisted for at least 5 weeks after discontinuing the treatment. Such an effect did not occur, however, in the group treated according to regimen 3. Hippocampal and cortical damage was not alleviated by FO. The present results demonstrate that FO-mediated memory recovery (or preservation) following TGCI is a reproducible, robust, and long-lasting effect. Moreover, such an effect was found with a relatively short period of treatment, provided it covered the first days prior to and after ischemia. This suggests that FO prevented amnesia by changing some acute, ischemia/reperfusion-triggered process and not by stimulating memory performance on its own.

Cystamine and intrabody co-treatment confers additional benefits in a fly model of Huntington's disease.

Huntington's disease (HD) is a lethal, neurodegenerative disorder caused by expansion of the polyglutamine repeat in the Huntingtin gene (HTT), leading to mutant protein misfolding, aggregation, and neuronal death. Feeding a Drosophila HD model cystamine, or expressing a transgene encoding the anti-htt intracellular antibody (intrabody) C4-scFv in the nervous system, demonstrated therapeutic potential, but suppression of pathology was incomplete. We hypothesized that a combinatorial approach entailing drug and intrabody administration could enhance rescue of HD pathology in flies and that timing of treatment would affect outcomes. Feeding cystamine to adult HD flies expressing the intrabody resulted in a significant, additional rescue of photoreceptor neurodegeneration, but no additional benefit in longevity. Feeding cystamine during both larval and adult stages produced the converse result: longevity was significantly improved, but increased photoreceptor survival was not. We conclude that cystamine-intrabody combination therapies can be effective, reducing neurodegeneration and prolonging survival, depending on administration protocols.

Ketogenic diet protects dopaminergic neurons against 6-OHDA neurotoxicity via up-regulating glutathione in a rat model of Parkinson's disease.

The high-fat ketogenic diet (KD) leads to an increase of blood ketone bodies (KB) level and has been used to treat refractory childhood seizures for over 80 years. Recent reports show that KD, KB and their components (d-beta-hydroxybutyrate, acetoacetate and acetone) have neuroprotective for acute and chronic neurological disorders. In our present work, we examined whether KD protected dopaminergic neurons of substantia nigra (SN) against 6-hydroxydopamine (6-OHDA) neurotoxicity in a rat model of Parkinson's disease (PD) using Nissl staining and tyrosine hydroxylase (TH) immunohistochemistry. At the same time we measured dopamine (DA) and its metabolites dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) in the striatum. To elucidate the mechanism, we also measured the level of glutathione (GSH) of striatum. Our data showed that Nissl and TH-positive neurons increased in rats fed with KD compared to rats with normal diet (ND) after intrastriatal 6-OHDA injection, so did DA and its metabolite DOPAC. While HVA had not changed significantly. The change of GSH was significantly similar to DA. We concluded that KD had neuroprotective against 6-OHDA neurotoxicity and in this period GSH played an important role.

The effects of a ketogenic diet on behavioral outcome after controlled cortical impact injury in the juvenile and adult rat.

The ketogenic diet has been shown to have unique properties that make it a more suitable cerebral fuel under various neuropathological conditions (e.g., starvation, ischemia, and traumatic brain injury (TBI). Recently, age-dependent ketogenic neuroprotection was shown among postnatal day 35 (PND35) and PND45 rats after TBI, but not in PND17 and PND65 animals (Prins et al., 2005). The present study addresses the therapeutic potential of a ketogenic diet on motor and cognitive deficits after TBI. PND35 and PND75 rats received sham or controlled cortical impact (CCI) surgery and were placed on either standard (Std) or ketogenic (KG) diet for 7 days. Beam walking and the Morris water maze (MWM) were used to assess sensory motor function and cognition, respectively. PND35 CCI Std animals showed significantly longer traverse times than sham and CCI KG animals at the beginning of motor training. Footslip analysis revealed better performance among the sham and the CCI KG animals compared to the CCI Std group. In the MWM PND35 CCI KG animals showed significantly shorter escape latencies compared to CCI Std-fed animals. During the same time period there was no significant difference between sham animals and CCI KG animals. The therapeutic effect of the ketogenic diet on beam walking and cognitive performance was not observed in PND75 animals. This finding supports our theory about age-dependent utilization and effectiveness of ketones as an alternative fuel after TBI.