Evidence For The Control Of Aggrecanases By Insulin And Glucose In Alzheimer'S Disease

Objective: Alzheimer's disease (AD) is a progressive and irreversible central nervous system disease, which slowly destroys cognitive skills and memory, and eventually even the ability to handle the simplest tasks. The initiation and progression of AD is a poorly understood complex process. Here, we have investigated possible biological mechanisms that could be responsible for the increased risk for diminished brain function associated with diabetes in AD. Method: The U87 cell line (human primary glioblastoma cell line) was cultured in Dulbecco's modified Eagle's medium. Cells were incubated with insulin (10 mu g/ml), low glucose (11 mM, 2 mg/ml) and high glucose (55 mM, 10 mg/ml) for 48 hours. Cells were harvested and protein isolations were performed. Primary anti-ADAMTS5, anti-IL-33, anti-NF kappa B, and anti-GAPDH antibodies were used to detect corresponding proteins and to measure band densities in Western membranes using a specific program. Results: Western blot analysis showed ADAMTS5 protein decreases in insulin-applied U87 cells. High glucose application led to a notable increase in ADAMTS5 levels in cells, while low glucose application caused a moderate increase in ADAMTS5 levels. An apparent induction of IL-33 protein was observed in high glucose-applied cells, while a moderate decrease was noted in the low-glucose applied group. Insulin administration led to a decrease in IL-33 levels. Immunoreaction of NF kappa B with corresponding antibody was found to be sharply decreased in insulin-applied cells while low and high glucose application led to a moderate decrease in NF kappa B. Conclusion: This is the first reported study that has investigated both aggrecanases and inflammation mediators in the same experimental setup with U87 cells and interpreted the results in the various aspects of AD pathophysiology related to diabetes and hyperglycemia. Our findings suggest that insulin and glucose may have important functions in the synthesis of ADAMTS, IL-33, and NF kappa B through undefined mechanism(s). Further investigations dealing with all aggrecanases and other class of ADAMTS enzymes should be carried out together with the above-mentioned parameters with the collaboration of molecular biology, genetics, immunology, and other related disciplines in order to elaborate the pathophysiological importance of ADAMTS enzymes and inflammation mediators in AD.WoSScopu

Glucocorticoid receptor blockade normalizes hippocampal alterations and cognitive impairment in streptozotocin-induced type 1 diabetes mice

Type 1 diabetes is a common metabolic disorder accompanied by an increased secretion of glucocorticoids and cognitive deficits. Chronic excess of glucocorticoids per se can evoke similar neuropathological signals linked to its major target in the brain, the hippocampus. This deleterious action exerted by excess adrenal stress hormone is mediated by glucocorticoid receptors (GRs). The aim of the present study was to assess whether excessive stimulation of GR is causal to compromised neuronal viability and cognitive performance associated with the hippocampal function of the diabetic mice. For this purpose, mice had type 1 diabetes induced by streptozotocin (STZ) administration (170 mg/kg, i.p.). After 11 days, these STZ-diabetic mice showed increased glucocorticoid secretion and hippocampal alterations characterized by: (1) increased glial fibrillary acidic protein-positive astrocytes as a marker reacting to neurodegeneration, (2) increased c-Jun expression marking neuronal activation, (3) reduced Ki-67 immunostaining indicating decreased cell proliferation. At the same time, mild cognitive deficits became obvious in the novel object-placement recognition task. After 6 days of diabetes the GR antagonist mifepristone (RU486) was administered twice daily for 4 days (200 mg/kg, p.o.). Blockade of GR during early type 1 diabetes attenuated the morphological signs of hippocampal aberrations and rescued the diabetic mice from the cognitive deficits. We conclude that hippocampal disruption and cognitive impairment at the early stage of diabetes are caused by excessive GR activation due to hypercorticism. These signs of neurodegeneration can be prevented and/or reversed by GR blockade with mifepristone. © 2009 Nature Publishing Group All rights reserved.Fil: Revsin, Yanina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Rekers, Niels V.. Leiden University Medical Center; Países BajosFil: Louwe, Mieke C.. Leiden University Medical Center; Países BajosFil: Saravia, Flavia Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: de Nicola, Alejandro Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Ron De Kloet, E. Leiden University Medical Center; Países BajosFil: Oitzl, Melly S.. Leiden University Medical Center; Países Bajo