Combined effects of radon inhalation and antioxidant vitamin administration on acute alcohol-induced hepatopathy in mice

Overview and trend analysis of global hot spring research based on bibliometrics and knowledge graph visualization

BACKGROUND

The scope of hot spring research is continuously growing, with the application of hot spring medicine emerging as a significant trend. However, there is a lack of bibliometric analyses that summarize the current state and trends of the application of hot spring medicine.

OBJECTIVES

Using bibliometric analysis, this study aims to visualize and analyze the global landscape and emerging trends in hot spring research, focusing on the hotspots and future directions of hot spring medicine application.

METHODS

Literature from 1994 to 2023 was compiled from the Web of Science Core Collection (WoSCC) database, visualized using Citespace and VOSviewer, analyzing publication trends, keyword co-occurrence, key institutions, and research directions in global hot spring studies. Similarly, literature on the application of hot spring medicine from 2000 to 2024 was also collected.

RESULTS

A total of 8,020 studies on the global field of hot springs and 68 studies on the application of hot spring medicine met the inclusion criteria. Linear regression reveals significant yearly increases in publication volume (p < 0.001). Five primary research trends including applications, components, diseases, mechanisms, and regions have been identified. Japan and France emerge as the primary contributor to the medical applications of hot springs.

CONCLUSION

Examining utilization patterns, conducting compositional tests, investigating therapeutic mechanisms, and scrutinizing geographical disparities aid in enhancing the comprehension of hot springs for medical applications. This validates the application of hot spring medicine as a frontier trend and new hotspot in hot spring research.

Potential inhibitory effects of low-dose thoron inhalation and ascorbic acid administration on alcohol-induced hepatopathy in mice

Although thoron inhalation exerts antioxidative effects in several organs, there are no reports on whether it inhibits oxidative stress-induced damage. In this study, we examined the combined effects of thoron inhalation and ascorbic acid (AA) administration on alcohol-induced liver damage. Mice were subjected to thoron inhalation at 500 or 2000 Bq/m3 and were administered 50% ethanol (alcohol) and 300 mg/kg AA. Results showed that although alcohol administration increased the levels of glutamic oxaloacetic transaminase (GOT) and glutamic pyruvic transaminase (GPT) in the serum, the combination of thoron inhalation (500 Bq/m3) and AA administration 24 h after alcohol administration effectively inhibited alcohol-induced liver damage. The combination of thoron inhalation (500 Bq/m3) and AA administration 24 h after alcohol administration increased catalase (CAT) activity. Alcohol administration significantly decreased glutathione (GSH) levels in the liver. The GSH content in the liver after 2000 Bq/m3 thoron inhalation was lower than that after 500 Bq/m3 thoron inhalation. These findings suggest that the combination of thoron inhalation at 500 Bq/m3 and AA administration has positive effects on the recovery from alcohol-induced liver damage. The results also suggested that thoron inhalation at 500 Bq/m3 was more effective than that at 2000 Bq/m3, possibly because of the decrease in GSH content in the liver. In conclusion, the combination of thoron inhalation at 500 Bq/m3 and AA administration promoted an early recovery from alcohol-induced liver damage.

Changes in Sulfur Metabolism in Mouse Brains following Radon Inhalation

Therapy using hot springs, including the high-level radioactive gas "radon", is traditionally conducted as an alternative treatment for various diseases. Oxidative-stress-related diseases are inhibited by the enhancement of antioxidative functions following radon inhalation. We have reported that radon inhalation increased the level of anti-oxidants, such as glutathione (G-SH), in the brain and had a protective antioxidative effect against transient global cerebral ischemic injury. However, no studies have yet revealed the changes in G-SH associated substances after radon inhalation. In this study, we comprehensively analyzed several metabolites, focusing on G-SH. Mice were exposed to radon at concentrations of 200, 2000, or 20,000 Bq/m³ for 1, 3, or 10 days. We detected 27 metabolites in the mouse brains. The result showed that the L-methionine levels increased, whereas the levels of urea, glutathione, and sulfite ion decreased under any condition. Although the ratio of G-SH to oxidized glutathione (GS-SG) decreased, glutathione monosulfide (G-S-SH) and cysteine monosulfide (Cys-S-SH) increased after radon inhalation. G-S-SH and Cys-S-SH can produce a biological defense against the imbalance of the redox state at very low-dose irradiation following radon inhalation because they are strong scavengers of reactive oxygen species. Additionally, we performed an overall assessment of high-dimensional data and showed some specific characteristics. We showed the changes in metabolites after radon inhalation using partial least squares-discriminant analysis and self-organizing maps. The results showed the health effects of radon, especially the state of sulfur-related metabolites in mouse brains under the exposure conditions for radon therapy.

Evaluation of the redox state in mouse organs following radon inhalation

Radon inhalation activates antioxidative functions in mouse organs, thereby contributing to inhibition of oxidative stress-induced damage. However, the specific redox state of each organ after radon inhalation has not been reported. Therefore, in this study, we evaluated the redox state of various organs in mice following radon inhalation at concentrations of 2 or 20 kBq/m3 for 1, 3 or 10 days. Scatter plots were used to evaluate the relationship between antioxidative function and oxidative stress by principal component analysis (PCA) of data from control mice subjected to sham inhalation. The results of principal component (PC) 1 showed that the liver and kidney had high antioxidant capacity; the results of PC2 showed that the brain, pancreas and stomach had low antioxidant capacities and low lipid peroxide (LPO) content, whereas the lungs, heart, small intestine and large intestine had high LPO content but low antioxidant capacities. Furthermore, using the PCA of each obtained cluster, we observed altered correlation coefficients related to glutathione, hydrogen peroxide and LPO for all groups following radon inhalation. Correlation coefficients related to superoxide dismutase in organs with a low antioxidant capacity were also changed. These findings suggested that radon inhalation could alter the redox state in organs; however, its characteristics were dependent on the total antioxidant capacity of the organs as well as the radon concentration and inhalation time. The insights obtained from this study could be useful for developing therapeutic strategies targeting individual organs.

Confirmation of efficacy, elucidation of mechanism, and new search for indications of radon therapy

Indications of radon therapy include various diseases related to respiratory, painful, digestive, chronic degenerative, senile, etc. derived from reactive oxygen species, but most are based on empirical prescriptions. For this reason, we have evaluated the relation between the biological response caused by radon and the tissue/organ absorbed dose more quantitatively, and have promoted the elucidation of mechanisms related to the indication and searching newly. As a result, as a mechanism, a series of moderate physiological stimulative effects accompanying a small amount of oxidative stress by radon inhalation are being elucidated. That is, hyperfunction of anti-oxidation/immune regulation/damage repair, promotion of anti-inflammation/circulating metabolism/hormone secretion, induction of apoptosis/heat shock protein, etc. Also, new indications include inflammatory/neuropathic pain, hepatic/renal injury, colitis, type 1 diabetes, complication kidney injury, hyperuricemia, transient cerebral ischemia, and inflammatory edema. Furthermore, we examined the combined antioxidant effect of radon inhalation and antioxidants or therapeutic agents. As a result, it was clear that any combination treatment could enhance the suppression effect of disease. It can be expected that radon therapy can be used effectively by applying it in addition to usual treatment, since reduction in its dosage can also be expected by concomitant use for drugs with strong side effects.