Changes in Sulfur Metabolism in Mouse Brains following Radon Inhalation

Area of Science:

• Biochemistry
• Toxicology
• Metabolomics

Background:

• Hot spring therapy, including radon inhalation, is an alternative treatment for diseases.
• Radon inhalation enhances antioxidative functions, potentially inhibiting oxidative-stress-related diseases.
• Previous research indicated radon increases brain glutathione (G-SH) and protects against ischemic injury, but associated substance changes were unknown.

Purpose of the Study:

• To comprehensively analyze changes in brain metabolites, particularly glutathione (G-SH) and related substances, following radon inhalation.
• To investigate the impact of varying radon concentrations and exposure durations on brain metabolite profiles.
• To elucidate the health effects of radon, focusing on sulfur-related metabolites and their role in redox balance.

Main Methods:

• Mice were exposed to radon at 200, 2000, or 20,000 Bq/m³ for 1, 3, or 10 days.
• Brain metabolites were analyzed using techniques including partial least squares-discriminant analysis and self-organizing maps.
• 27 metabolites were detected and quantified to assess changes post-exposure.

Main Results:

• Radon inhalation led to increased L-methionine and decreased urea, glutathione, and sulfite ion levels.
• The ratio of glutathione (G-SH) to oxidized glutathione (GS-SG) decreased.
• Levels of glutathione monosulfide (G-S-SH) and cysteine monosulfide (Cys-S-SH) increased, indicating potential redox protective mechanisms.

Conclusions:

• Radon inhalation significantly alters brain metabolite profiles, with notable changes in sulfur-related compounds.
• Increased G-S-SH and Cys-S-SH may act as biological defenses against redox imbalance caused by low-dose radon irradiation.
• Findings provide insights into the health effects of radon therapy, particularly concerning its impact on sulfur metabolism and antioxidant defense in the brain.