This study examined inflammatory cell and cytokine production in brain tissue from a lipopolysaccharide (LPS)-treated rat model that mimics many of the neuropathologic changes associated with neurodegenerative diseases We also monitored the appearance of a glial cell line-derived neurotrophic factor (GDNF) and circulating nitric oxide (NO) levels, as well as an immune system-associated cells in a selected area of the brain, the olfactory lobe. The studies were based on the hypothesis that LPS treatment stimulates temporal changes within the brain and that these responses include immune cell recruitment, increased tissue levels of immune modulating cytokines and NO, as well as greater glial cell activation resulting in increased production of GDNF. As previously reported by other investigators, our animal model of systemic LPS treatment leads to an increase in the concentrations of circulating cytokines, including TNF-α, IL-Iβ, and IL-6, with a maximum response 6 h post LPS administration. Concomitant with cytokine elevations, circulating NO levels were elevated for several hours post LPS administration. The brain content of the GDNF was also elevated over a similar time frame. Lymphocytes, neutrophils, macrophages, plasma cells, and cytokines were all seen in various areas of LPS-treated brains, often around blood vessels associated with the meninges, with these localizations possibly indicating involvement of both the blood–brain and blood–cerebral spinal fluid barriers in these inflammatory episodes. Our results suggest an involvement of both the peripheral and the central nervous system immune components in response to inflammation and inflammatory episodes. This leads us to propose that inflammation initiates an immune response by activating both microglia and astrocytes and that the presence of continuing and increasing proinflammatory mechanisms results in a situation, where cellular protective mechanisms are overcome and the more susceptible cells enter into cell death pathways, initiating a train of events that is a major part of neurodegeneration.
Background: Excessive and abnormal accumulation of alpha-synuclein (α-synuclein) is a factor contributing to pathogenic cell death in Parkinson's disease. The purpose of this study, based on earlier observations of Parkinson's disease cerebrospinal fluid (PD-CSF) initiated cell death, was to determine the effects of CSF from PD patients on the functionally different microglia and astrocyte glial cell lines. Microglia cells from human glioblastoma and astrocytes from fetal brain tissue were cultured, grown to confluence, treated with fixed concentrations of PD-CSF, non-PD disease control CSF, or control no-CSF medium, then photographed and fluorescently probed for α-synuclein content by deconvolution fluorescence microscopy. Outcome measures included manually counted cell growth patterns from day 1-8; α-synuclein density and distribution by antibody tagged 3D model stacked deconvoluted fluorescent imaging. Results: After PD-CSF treatment, microglia growth was reduced extensively, and a non-confluent pattern with morphological changes developed, that was not evident in disease control CSF and no-CSF treated cultures. Astrocyte growth rates were similarly reduced by exposure to PD-CSF, but morphological changes were not consistently noted. PD-CSF treated microglia showed a significant increase in α-synuclein content by day 4 compared to other treatments (p ≤ 0.02). In microglia only, α-synuclein aggregated and redistributed to peri-nuclear locations. Conclusions: Cultured microglia and astrocytes are differentially affected by PD-CSF exposure compared to non-PD-CSF controls. PD-CSF dramatically impacts microglia cell growth, morphology, and α-synuclein deposition compared to astrocytes, supporting the hypothesis of cell specific susceptibility to PD-CSF toxicity.
6 February 2007 in Journal of Toxicology and Environmental Health, Part A
Oleanders are common, hardy shrubs that grow throughout the southern United States. They contain cardiotonic steroids formed from cardenolides and bufadienolides, making the plant poisonous to both animals and humans. Aliquots of both commercially available oleander and fresh oleander extracts were prepared. Fresh, rod-like, calcium-tolerant adult rat cardiomyocytes and cultured neonatal cardiomyocytes were isolated and treated with 0–4 ng/ml of both preparations, challenged with verapamil and ouabain, and real-time spectrophotometric calcium transients and images were acquired. A number of effects were observed with the adult cells: (1) intracellular calcium levels were increased in a concentration-dependent manner: (2) reduced calcium transient heights and eventual cessation of beating resulted; and (3) increased sparking intensity led to subsequent beating and eventual calcium overload. In the spontaneously beating cultured neonatal myocytes increased intramyocytic calcium levels were also seen, with retention of this calcium rise leading to overload and, as in the adult myocytes, cessation of beating. These observations demonstrate that oleander extract is markedly potent with respect to the elevation of calcium concentrations in cardiomyocytes, and that the inability of the cardiomyocytes to release the accumulated calcium possibly indicates a role for oleandrin in inhibition of ryanodine receptor calcium release channels, calcium uptake via Na+,K+-ATPase inhibition [EC 3.6.1.3], and/or dysfunction of sarcolemmal calcium release channels.
The use of left ventricular (LV) assist devices (LVADs) can improve performance and recovery of failing human hearts. Following our alpha-adrenergic receptor work, we hypothesized that mechanical unloading in patients with low output syndrome and LV failure would yield similar results with beta-adrenergic receptors ((beta)AR), that being increased numbers and intra-myocytic relocalization. (beta)AR density and localization were investigated by fluorescence deconvolution microscopy and compared at LVAD insertion and removal in 13 heart failure patients, the patients therefore acting as their own control. (beta)AR densities and distribution were determined in snap frozen sections of human core biopsy left ventricular apical tissue. Samples were probed with tagged CGP 12177 for visualization of (beta)AR and challenged with cold agonists and antagonists. (beta)AR density was measured by two independent methods. Localization of receptors was examined in reconstructed, deconvoluted, stacked section images. There was an increase in (beta)AR density following ventricular unloading in most of the patients, and also significant normalization in the location of the receptors in the myocardium comparing pre- and post-LVAD tissue. These findings suggest that supporting an ailing heart via unloading initiates mechanisms and pathways responsible for myocardial recovery and repair. With appropriate pharmacological support, patients with LVAD might recover to the point where they no longer depend on eventual organ transplantation, and (beta)AR number, type, and distribution in pre-LVAD myocardial tissue, could predict outcome with regard to recovery, repair, and improvement in cardiac function.