Influence of histone deacetylases inhibitor sodium butyrate on hippocampal neuronal activity in vivo

Epigenetic regulation plays an important role in cognitive brain functions. The increase in histone acetylation by histone deacetylase inhibitors, such as sodium butyrate, was shown previously to be highly correlated with memory enhancement. Currently, the data on sodium butyrate effects on neuronal activity in vivo are limited. This study investigates how sodium butyrate affects the activity of CA1 hippocampal neurons in freely behaving mice. We performed in vivo calcium imaging of CA1 neurons with miniscopes in mice during arena exploration trials. The first trial was followed by an intraperitoneal injection of sodium butyrate or saline. After 45 and 90 minutes, CA1 neurons were recorded again in the homecage. The second trial was made 24 hours later. The injection of sodium butyrate resulted in immediate inhibition of neuronal activity for the following 90 minutes. However, the population activity analysis revealed that neurons that were active in the first behavioral trial demonstrated significantly more correlated activity during the second trial in the sodium butyrate group, but not in the saline group. Thus, for the first time, we demonstrated the effects of sodium butyrate on neuronal activity in vivo .