One epigenetic factor, known as HDAC4, as well as one organic anion transporter (OAT1) contribute to the development of chronic pain. The underlying molecular mechanism was identified by a team of researchers led by Dr Daniela Mauceri at Heidelberg University. Using mouse models, the researchers demonstrated that HDAC4 influences the expression of genes in neuronal cells involved in the processing of pain. The experiments also revealed that OAT1 regulates pain sensitivity in the spinal cord.