Butyric acid is an  inhibitor that is selective for class I HDACs in humans. HDACs are histone-modifying enzymes that can cause histone deacetylation and repression of gene expression. HDACs are important regulators of synaptic formation, synaptic plasticity, and long-term memory formation. Class I HDACs are known to be involved in mediating the development of an addiction. Butyric acid and other HDAC inhibitors have been used in preclinical research to assess the transcriptional, neural, and behavioral effects of HDAC inhibition in animals addicted to drugs.