when the nerve conductor loses its rhythm

This content was created by Laval University.

Research published in a scientific journal electronic life A research team from Laval University suggests that a family of neurons that acts as a conductor of neuronal activity in the memory-related region of the brain may play an important role in the early stages of Alzheimer’s disease. This study shows that the firing rate of these neurons is reduced by 50% even before the first behavioral manifestations of Alzheimer’s disease occur in an animal model of the disease.

To demonstrate this, the research team studied neurons called specific interneurons type 3 (I-S3) in the hippocampus, an area of ​​the brain associated with memory and spatial orientation that is affected in the early stages of Alzheimer’s disease. “Approximately 90% of the neurons in this area are pyramidal cells, which encode information. Their activity is regulated by interneurons, which are themselves controlled by I-S3 cells. Thus, the latter act as a conductor for neural networks,” explains study leader Lisa Topolnik, professor in the department of biochemistry, microbiology and bioinformatics and researcher at the Research Center of the University of Quebec-Laval.

To study the role of I-S3 cells in the development of Alzheimer’s disease, the research team crossed transgenic mice that exhibit the core features of Alzheimer’s disease with transgenic mice that produce green fluorescent protein in their I-S3 cells. “This allows us to localize I-S3 cells in the brain and study their morphology and physiology as mice age and Alzheimer’s disease progresses,” explains Professor Topolnik.

Observations made on these mice from 90 to 260 days of age showed that the numbers and morphology of their I-S3 cells remained unchanged. “On the other hand, the discharge rate of these regulatory interneurons decreased by approximately 30–50%,” the researcher emphasizes. Thus, poor functioning of these cells can lead to imbalances in neural networks, which can have consequences for memory.

“A drug that specifically targets I-S3 cell ion channels will expand the range of treatments for people with Alzheimer’s disease. »

— Lisa Topolnik

Professor Topolnik believes that the evolution of the first phases of Alzheimer’s disease could be reversed if there was a way to restore normal activity of I-S3 cells. “Our results show that certain ion channels in these cells are damaged, which explains why their activation rate is reduced. This makes them interesting therapeutic targets, especially since the four drugs currently approved in Canada for the treatment of Alzheimer’s disease use different cellular mechanisms. A drug that specifically targets I-S3 cell ion channels will expand the range of treatments for people with Alzheimer’s disease.”

Signatories of the study published in electronic life Felix Michaud, Ruggero Francavilla, Dmitry Topolnik, Parisa Ilun, Suhel Tamboli, Frederic Kalon and Lisa Topolnik.