Researchers Discover Memory Switch That Plays Role in Memory and Addiction

Researchers Discover Memory Switch That Plays Role in Memory and Addiction

Researchers have identified a molecular switch that plays an important role in forming memory and addictive behaviors. The formation of these behaviors depend on the creation of new connections between neurons in the brain. Addiction behaviors manifest in long-term alterations in neuron connections and can be viewed as a type of learning.

Led by Pierluigi Nicotera, scientific director of the German Center for Neurodegenerative Diseases (DZNE), a team of researchers from Germany, the UK, and Italy have discovered a molecular switch that is associated with establishing addictive behavior and memory processes. The findings could help scientist develop treatments for memory loss and addiction.

Neurotransmitters help neuronal signals pass from one nerve cell to the next; this is a the first step for any learning process, and sets into motion a sequence of events that lead to changes in neuronal connectivity and memory. Substances like nicotine and cocaine can also trigger this change in brain connections.

Nueronal plasticity, or the formation of new connections in the brain, involves calcium. In response to neurotransmitters, nicotine, or cocaine, the brain creates more calcium at the synapse, where the neuronal connection takes place. The increased calcium induces gene expression, or the synthesis of proteins that lead to new synaptic connectivity. Although it has been generally accepted that the increase in calcium is only part of the first step in this process and does not depend on gene expression, Nicotera and colleagues are challenging this idea.

The new study shows that gene expression involved in calcium signaling is required to induce plasticity in nerve cells after repeated exposure to nicotine or cocaine. After giving nicotine to mice, they found that the nicotine induced the expression of a gene called type 2 ryanodine receptor (RyR2), which is associated with releasing calcium from the endoplasmic reticulum, leading to neuronal plasticity.

RyR2 is expressed in several brain regions that are associated with cognition and addiction, suggesting that it plays an important role in these processes. In another experiment, the researchers confirmed this theory by demonstrating that reducing RyR2 in living animals alters behaviors associated with learning, memory, and addiction. This suggests that RyR2 is necessary for developing long-term changes in the brain that can lead to addiction.

The researchers hope that these findings could help develop more efficient treatments for both memory loss and addiction.

Source: Science Daily, A Molecular Switch for Memory and Addiction, November 26, 2010

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