Chronic hyponatremia is a condition in which blood sodium levels are low, leading to neurological and mental problems. Rapid treatment can cause a severe nerve disorder called ODS, which affects brain function and can be life-threatening.
Researchers from Fujita Health University found that low sodium levels also affect microglial cells in the brain, reducing their production of nitric oxide, a key molecule for cell signaling.
Understanding ODS is essential to treating hyponatremia without causing complications. Professor Yoshihisa Sugimura from Fujita Health University found that microglia, immune cells in the brain, may play a key role in ODS.
In a new study, Sugimura’s team discovered that low sodium levels reduce microglia activity, specifically lowering certain mRNA expression and nitric oxide production, which could explain ODS development.
Microglia are brain cells involved in vital functions like creating new neurons, adjusting synapses, and forming myelin. They respond to infections or damage by producing chemicals, including nitric oxide, that cause inflammation.
Prof. Sugimura’s team studied how low sodium affects microglia because it could help treat ODS and hyponatremia-related brain issues. They found that low sodium levels reduce the production of an enzyme (Nos2) that controls nitric oxide, which is critical for inflammation.
The team also discovered that low sodium affects a protein (NFAT5) that helps cells handle stress, showing a connection between sodium levels and brain cell function.
When microglial cells were exposed to a quick correction of low sodium levels, researchers noticed a sharp increase in nitric oxide (NO) production. This suggests that rapid treatment of hyponatremia may trigger ODS by increasing NO levels.
The team also found reduced levels of important mRNA in brain cells of chronic hyponatremia model mice. These findings help explain how long-term low sodium and its fast correction affect brain cells. They may lead to new treatments for hyponatremia and related brain issues.
Journal reference :
- Haruki Fujisawa a, Takashi Watanabe et al., Prolonged extracellular low sodium concentrations and subsequent their rapid correction modulate nitric oxide production dependent on NFAT5 in microglia. Free Radical Biology and Medicine. DOI: 10.1016/j.freeradbiomed.2024.08.019.
