Why cocaine is so addictive

Washington, Aug 26 (ANI):A new study has suggested a way in which cocaine use may lead to drug-seeking behaviour that fosters continued drug use.

According to a research team from the Ernest Gallo Clinic and Research Center at UC San Francisco, mice given cocaine showed rapid growth in new brain structures associated with learning and memory.

The researchers used a microscope that allowed them to peer directly into nerve cells within the brains of living mice, and within two hours of giving a drug they found significant increases in the density of dendritic spines - structures that bear synapses required for signaling - in the animals' frontal cortex. In contrast, mice given saline solution showed no such increase.

The researchers also found a relationship between the growth of new dendritic spines and drug-associated learning.

The study suggested that mice that grew the most new spines were those that developed the strongest preference for being in the enclosure where they received cocaine rather than in the enclosure where they received saline.

Principal investigator Linda Wilbrecht, PhD, a Gallo investigator now at UC Berkeley, but who led the research said that it's been observed that long-term drug users show decreased function in the frontal cortex in connection with mundane cues or tasks, and increased function in response to drug-related activity or information.

Wilbrecht said that in a series of experiments, the animals that showed the highest quantity of robust dendritic spines - the spines with the greatest likelihood of developing into synapses - showed the greatest change in preference toward the chamber where they received the cocaine.

"This suggests that the new spines might be material for the association that these mice have learned to make between the chamber and the drug," the researcher said.

The study is published in the journal Nature Neuroscience. (ANI)


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