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Serotonin can regulate gene expression inside neurons -- ScienceDaily

The study revolves around DNA and how it works to form each person's individual biological map. Each cell in the body contains two meters of DNA, the blueprint for all functions of all cells in the body. This DNA is wound around spools of histone proteins (proteins that package DNA in the nucleus of cells, and are heavily prone to chemical modifications that aid in the regulation of gene expression) into structures referred to as nucleosomes. When DNA encoding a specific gene is wound tightly within the spool, that gene is less likely to be expressed. When the gene is not wound as tightly, it is more likely to be expressed. This can affect many functions of a given cell. Serotonin is a chemical that can transmit signals between neurons in the brain and is involved in the regulation of mood. Selective serotonin reuptake inhibitors, known as SSRIs, alter the amounts of serotonin in the brain, which enables mood changes. When small packages of serotonin are released from a neuron, the resulting signals set up a chain reaction of communication between different parts of the brain. The research team discovered that a protein called tissue transglutaminase 2 can directly attach serotonin molecules to histone proteins (a process called histone serotonylation), which in turn loosens the spool to enable more robust gene expression. Specifically, they found that in developing rodent brains and human neurons, genes near the part of the spool loosened by the serotonin are more likely to be expressed. They also showed that a specific binding complex enables this process.

Heavy drinking may change DNA, leading to increased craving for alcohol: Genetic vicious cycle may reinforce risky drinking behavior -- ScienceDaily

Scientists at Rutgers and Yale University School of Medicine focused on two genes implicated in the control of drinking behavior: PER2, which influences the body's biological clock, and POMC, which regulates our stress-response system. By comparing groups of moderate, binge and heavy drinkers, the researchers found that the two genes had changed in the binge and heavy drinkers through an alcohol-influenced gene modification process called methylation. The binge and heavy drinkers also showed reductions in gene expression, or the rate at which these genes create proteins. These changes increased with greater alcohol intake. Additionally, in an experiment, the drinkers viewed stress-related, neutral or alcohol-related images. They also were shown containers of beer and subsequently tasted beer, and their motivation to drink was evaluated. The result: alcohol-fueled changes in the genes of binge and heavy drinkers were associated with a greater desire for alcohol.