Brain deterioration resulting from "protein folding" diseases, such as the Alzheimer's disease (AD), is one of the leading causes of morbidity and mortality in the aging human population. Heat shock proteins (Hsps) constitute the major cellular quality control system for proteins that mitigates the pathological burden of neurotoxic protein fibrils and aggregates. However, the therapeutic effect of Hsps has not been tested in a relevant setting. Here we report the dramatic neuroprotective effect of recombinant human Hsp70 in the bilateral olfactory bulbectomy model (OBX mice) and 5XFAD mouse models of neurodegeneration. We show that intranasally-administered Hsp70 rapidly enters the afflicted brain regions and mitigates multiple AD-like morphological and cognitive abnormalities observed in model animals. In particular, in both cases it normalizes the density of neurons in the hippocampus and cortex which correlates with the diminished accumulation of amyloid-β (Aβ) peptide and, in the case of 5XFAD mice, reduces Aβ plaque formation. Consistently, Hsp70 treatment also protects spatial memory in OBX and 5XFAD mice. These studies demonstrate that exogenous Hsp70 may be a practical therapeutic agent for treatment of neurodegenerative diseases associated with abnormal protein biogenesis and cognitive disturbances, such as AD, for which neuroprotective therapy is urgently needed.

PTZ kindling model may improve understanding of the seizures development provided that the differences existing between the phases of kindling model are taken into account.

Molecular chaperone Heat Shock Protein 70 (Hsp70) plays an important protective role in various neurodegenerative disorders often associated with aging, but its activity and availability in neuronal tissue decrease with age. Here we explored the effects of intranasal administration of exogenous recombinant human Hsp70 (eHsp70) on lifespan and neurological parameters in middle-aged and old mice. Long-term administration of eHsp70 significantly enhanced the lifespan of animals of different age groups. Behavioral assessment after 5 and 9 mo of chronic eHsp70 administration demonstrated improved learning and memory in old mice. Likewise, the investigation of locomotor and exploratory activities after eHsp70 treatment demonstrated a significant therapeutic effect of this chaperone. Measurements of synaptophysin show that eHsp70 treatment in old mice resulted in larger synaptophysin-immunopositive areas and higher neuron density compared with control animals. Furthermore, eHsp70 treatment decreased accumulation of lipofuscin, an aging-related marker, in the brain and enhanced proteasome activity. The potential of eHsp70 intranasal treatment to protect synaptic machinery in old animals offers a unique pharmacological approach for various neurodegenerative disorders associated with human aging.

Six weeks after bilateral olfactory bulbectomy, a peptide with molecular weight of 4 kD was revealed in extracts of the neocortex and hippocampus from mice. Using monoclonal antibodies 4G8, this peptide was identified as beta-amyloid. Its level was significantly higher in the bulbectomized animals than in sham-operated mice. The bulbectomized mice displayed sharp impairment in spatial memory when tested in the Morris water maze. The results suggest that bulbectomy initiates in the brain a pathological process similar to human Alzheimer's disease in location, biochemistry, and behavioral manifestations.

Heat shock protein 70, encoded by the HSPA1A gene in humans, is a key component of the machinery that protects neuronal cells from various stress conditions and whose production significantly declines during the course of aging and as a result of several neurodegenerative diseases. Herein, we investigated whether sub-chronic intranasal administration of exogenous Hsp70 (eHsp70) exerts a neuroprotective effect on the temporal cortex and areas of the hippocampus in transgenic 5XFAD mice, a model of Alzheimer's disease. The quantitative analysis of neuronal pathologies in the compared groups, transgenic (Tg) versus non-transgenic (nTg), revealed high level of abnormalities in the brains of transgenic mice. Treatment with human recombinant Hsp70 had profound rejuvenation effect on both neuronal morphology and functional state in the temporal cortex and hippocampal regions in transgenic mice. Hsp70 administration had a smaller, but still significant, effect on the functional state of neurons in non-transgenic mice as well. Using deep sequencing, we identified multiple differentially expressed genes (DEGs) in the hippocampus of transgenic and non-transgenic mice. Furthermore, this analysis demonstrated that eHsp70 administration strongly modulates the spectrum of DEGs in transgenic animals, reverting to a pattern similar to that observed in non-transgenic age-matched mice, which included upregulation of genes responsible for amine transport, transmission of nerve impulses and other pathways that are impaired in 5XFAD mice. Overall, our data indicate that Hsp70 treatment may be an effective therapeutic against old age diseases of the Alzheimer's type.