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Induction of muscle-relaxing factor by staphylococcal alpha-toxin
1Department of Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232.
Abstract:
Brain tissue and serum from mice intracerebrally injected with 1 microgram of staphylococcal alpha-toxin contained elevated amounts of a naturally occurring brain tissue component(s) called muscle-relaxing factor (MRF). MRF induced reversible, generalized, flaccid paralysis of mice after intracerebral but not intraperitoneal or intravenous administration. MRF (i) was soluble in Hanks balanced salt solution and in acidified (pH 2) Hanks balanced salt solution, in which it partitions into ethyl acetate, acetone, and methanol; (ii) was separated from some pigments by thin-layer chromatography on silica gel plates; (iii) did not comigrate with prostaglandin and leukotriene standards during high-pressure liquid chromatography with a mu Bondapak fatty acid column; and (iv) did not contain amino acids, exhibit absorption maxima at a wavelength range of 210 to 600 nm, or fluoresce when exposed to UV light. MRF has been detected in rabbit brain that has been stored frozen at -70 degrees C and has been enhanced in vitro in slices of both mouse and rabbit brain following incubation of the brain slices with staphylococcal alpha-toxin. Studies to identify the chemical nature of MRF and the mechanism by which, in mice, it induces reversible, flaccid paralysis of voluntary muscle are continuing.
Insights
Staphylococcal alpha-toxin exposure increased muscle-relaxing factor (MRF) in mouse brains. This naturally occurring brain component, MRF, caused reversible paralysis in mice upon direct brain administration.
Area of Science:
- Neuroscience
- Toxicology
- Biochemistry
Background:
- Staphylococcal alpha-toxin is a potent neurotoxin.
- Naturally occurring brain components may play a role in neurotoxicity.
- Understanding endogenous factors involved in toxin-induced neurological effects is crucial.
Purpose of the Study:
- To investigate the role of naturally occurring brain components in staphylococcal alpha-toxin-induced neurological effects.
- To identify and characterize a novel brain component, muscle-relaxing factor (MRF), associated with toxin exposure.
- To determine the effects of MRF on motor function in mice.
Main Methods:
- Mice were intracerebrally injected with staphylococcal alpha-toxin.
- Brain tissue and serum were analyzed for elevated naturally occurring components.
- Muscle-relaxing factor (MRF) was isolated and characterized using solubility, chromatography (thin-layer and high-pressure liquid), and spectroscopic methods.
- MRF's effects on motor function were assessed following different administration routes (intracerebral, intraperitoneal, intravenous).
Main Results:
- Intracerebral injection of staphylococcal alpha-toxin led to elevated levels of muscle-relaxing factor (MRF) in mouse brain tissue and serum.
- MRF administration induced reversible, generalized, flaccid paralysis in mice following intracerebral, but not peripheral, injection.
- MRF exhibited specific solubility properties and was chromatographically separated from prostaglandins and leukotrienes; it lacked amino acids and characteristic UV-Vis absorption or fluorescence.
Conclusions:
- Staphylococcal alpha-toxin exposure enhances the levels of a naturally occurring brain component, MRF.
- MRF is implicated in the induction of reversible, flaccid paralysis following direct central nervous system administration.
- Further research is ongoing to elucidate the precise chemical nature of MRF and its mechanism of action in inducing paralysis.