Bilingual neurons “speak” in sync

MCGILL (CAN) (US) — Single neurons are able to communicate in more than one “language” at a time to exchange information, a finding that may lead to better understanding of brain function and neural disease.

“Our work could facilitate the identification of mechanisms that disrupt the function of dopaminergic, serotonergic and cholinergic neurons in diseases such as schizophrenia, Parkinson’s and depression,” write Salah El Mestikawy, professor of psychiatry at McGill University and Louis-Eric Trudeau, professor of pharmacology at the University of Montreal in a new study.

Details are published in the journal Nature Reviews Neuroscience.

Results show that many neurons in the brain are able to control cerebral activity by simultaneously using two chemical messengers or neurotransmitters, a mode of communication known as “cotransmission.”

“The neurons in the nervous system—both in the brain and in the peripheral nervous system—are typically classified by the main transmitter they use,” Trudeau says.

For example, dopaminergic neurons use dopamine as a transmitter to communicate important information for different phenomena, including motivation and learning. The malfunction of these neurons is involved in serious brain diseases such as schizophrenia and Parkinson’s.

“Our recent research, shows that dopaminergic neurons use glutamate as a second transmitter. That means they are able to transmit two types of messages in the brain, on two time scales: a fast one for glutamate and a slower one for dopamine.”

Previous research has observed the same kind of bilingualism in brain neurons that use serotonin, a group of cells that communicate important information for controlling mood, aggression, impulsivity, and food intake, and also those that use acetylcholine, an important messenger for motor skills and memory that is unbalanced by Parkinson’s disease, antipsychotic drugs, and in drug addiction.

Joint studies suggest that the secretion of glutamate by dopaminergic neurons could, for example, be involved in the behavioral effects of psychostimulants such as amphetamines and cocaine.

“We know very little about the role of cotransmission in disease and the regulation of behavior, however,” Trudeau says. “That will have to be the subject of future studies.”

The studies were funded by the National Alliance for Research on Schizophrenia and Depression, the Canadian Institutes of Health Research, the Swedish Foundation for International Cooperation in Research, and Higher Education and the Agence Nationale pour la Recherche (France).

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