Prevention of hexachlorocyclohexane-induced neuronal oxidative stress by natural antioxidants

4-Hydroxyisophthalic acid from Decalepis hamiltonii rescues the neurobehavioral deficit in transgenic Drosophila model of taupathies

Oxidative stress is one of the major etiological factors implicated in pathogenesis of neurodegenerative diseases. Since neurons are more sensitive to oxidative damage there is an increasing interest in developing novel antioxidant therapies, especially herbal preparations due to their safety profile and high efficiency. In this regard, the neuroprotective potential of a novel antioxidant compound, 4-hydroxyisophthalic acid (4-HIPA) isolated from aqueous extract of Decalepis hamiltonii roots was examined using transgenic Drosophila model of taupathy expressing wild-type and mutant forms of 2N4R isoform of human microtubule associated protein tau (MAPT). Taupathy model flies showed cognitive deficits in olfactory memory and deteriorated circadian rhythm of locomotory activities. Administration of 0.1 mg/ml 4-HIPA, markedly enhanced their olfactory memory performance and restored circadian rhythmicity of the transgenic flies locomotory behavior to the normal range. The mechanism of action that underlies 4-HIPA neuroprotection involves enhancement in efficiency of cellular antioxidant defense system by means of elevation in antioxidant enzyme activities and attenuation of oxidative stress. The molecule could positively affect the activity of neurotransmitter enzymes, which in turn enhances neuronal function and ameliorates the Tau-induced neurobehavioral deficits. Our findings showed that 4-HIPA can be considered as a suitable therapeutic candidate for drug development towards treatment of neurodegenerative disorders.

Neuroprotective effect of Decalepis hamiltonii on cyclophosphamide-induced oxidative stress in the mouse brain

BACKGROUND

Cyclophosphamide (CP), one of the most widely used antineoplastic drugs, causes toxic side effects on vital organs including brain. In this study, we have investigated neuroprotective potential of the aqueous extract of the roots of Decalepis hamiltonii (DHA) against CP-induced oxidative stress in the mouse brain.

METHODS

Swiss albino male mice were pre-treated with DHA (50 and 100 mg/kg b.w.) for 10 consecutive days followed by an injection with CP intraperitoneally (25 mg/kg b.w.) for 10 days 1 h after DHA treatment; 16 h later, they were euthanized, their brains were immediately removed, and biochemical and molecular analyses were conducted.

RESULTS

The results indicated that injection of CP induced oxidative stress in the mouse brain as evident from the increased lipid peroxidation, reactive oxygen species, depletion of glutathione and reduced activities of the antioxidant enzymes such as superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, and glutathione-S-transferase. Treatment with DHA significantly mitigated the CP-induced oxidative stress. Moreover, expression of genes for the antioxidant enzymes was downregulated by CP treatment which was reversed by DHA.

CONCLUSIONS

In conclusion, DHA protected the brain from oxidative stress induced by CP, and therefore, it could be a promising nutraceutical as a supplement in cancer chemotherapy in order to ameliorate the toxic side effects of cancer drugs.

FoxO proteins in the nervous system

Acute as well as chronic disorders of the nervous system lead to significant morbidity and mortality for millions of individuals globally. Given the ability to govern stem cell proliferation and differentiated cell survival, mammalian forkhead transcription factors of the forkhead box class O (FoxO) are increasingly being identified as potential targets for disorders of the nervous system, such as Alzheimer's disease, Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis, and auditory neuronal disease. FoxO proteins are present throughout the body, but they are selectively expressed in the nervous system and have diverse biological functions. The forkhead O class transcription factors interface with an array of signal transduction pathways that include protein kinase B (Akt), serum- and glucocorticoid-inducible protein kinase (SgK), IκB kinase (IKK), silent mating type information regulation 2 homolog 1 (S. cerevisiae) (SIRT1), growth factors, and Wnt signaling that can determine the activity and integrity of FoxO proteins. Ultimately, there exists a complex interplay between FoxO proteins and their signal transduction pathways that can significantly impact programmed cell death pathways of apoptosis and autophagy as well as the development of clinical strategies for the treatment of neurodegenerative disorders.

New Insights for Oxidative Stress and Diabetes Mellitus

The release of reactive oxygen species (ROS) and the generation of oxidative stress are considered critical factors for the pathogenesis of diabetes mellitus (DM), a disorder that is growing in prevalence and results in significant economic loss. New therapeutic directions that address the detrimental effects of oxidative stress may be especially warranted to develop effective care for the millions of individuals that currently suffer from DM. The mechanistic target of rapamycin (mTOR), silent mating type information regulation 2 homolog 1 (S. cerevisiae) (SIRT1), and Wnt1 inducible signaling pathway protein 1 (WISP1) are especially justified to be considered treatment targets for DM since these pathways can address the complex relationship between stem cells, trophic factors, impaired glucose tolerance, programmed cell death pathways of apoptosis and autophagy, tissue remodeling, cellular energy homeostasis, and vascular biology that greatly impact the biology and disease progression of DM. The translation and development of these pathways into viable therapies will require detailed understanding of their proliferative nature to maximize clinical efficacy and limit adverse effects that have the potential to lead to unintended consequences.

Novel applications of trophic factors, Wnt and WISP for neuronal repair and regeneration in metabolic disease

Diabetes mellitus affects almost 350 million individuals throughout the globe resulting in significant morbidity and mortality. Of further concern is the growing population of individuals that remain undiagnosed but are susceptible to the detrimental outcomes of this disorder. Diabetes mellitus leads to multiple complications in the central and peripheral nervous systems that include cognitive impairment, retinal disease, neuropsychiatric disease, cerebral ischemia, and peripheral nerve degeneration. Although multiple strategies are being considered, novel targeting of trophic factors, Wnt signaling, Wnt1 inducible signaling pathway protein 1, and stem cell tissue regeneration are considered to be exciting prospects to overcome the cellular mechanisms that lead to neuronal injury in diabetes mellitus involving oxidative stress, apoptosis, and autophagy. Pathways that involve insulin-like growth factor-1, fibroblast growth factor, epidermal growth factor, and erythropoietin can govern glucose homeostasis and are intimately tied to Wnt signaling that involves Wnt1 and Wnt1 inducible signaling pathway protein 1 (CCN4) to foster control over stem cell proliferation, wound repair, cognitive decline, β-cell proliferation, vascular regeneration, and programmed cell death. Ultimately, cellular metabolism through Wnt signaling is driven by primary metabolic pathways of the mechanistic target of rapamycin and AMP activated protein kinase. These pathways offer precise biological control of cellular metabolism, but are exquisitely sensitive to the different components of Wnt signaling. As a result, unexpected clinical outcomes can ensue and therefore demand careful translation of the mechanisms that govern neural repair and regeneration in diabetes mellitus.