In a study on mice, researchers at the National Institutes of Health identified and mapped a broad spectrum of motor neurons along the spinal cord. These neurons, which send and receive messages throughout the body, include a subset sensitive to neurodegenerative diseases. Created with a genetic sequencing technique, the atlas reveals 21 subtypes of neurons in discrete areas of the spinal cord and offers insight into how these neurons control movement, how they contribute to the functioning of organ systems and why some are disproportionately affected in neurodegenerative diseases.
The study was led by Claire Le Pichon, Ph.D., head of the Neurodegeneration Development Unit at the National Institute of Child Health and Human Development (NICHD) at NIH Eunice Kennedy Shriver. It appears in Nature communications.
Neurons in the spinal cord are responsible for all types of movement in the body, ranging from voluntary movements like walking to involuntary constriction and relaxation of the stomach as it processes its contents. Traditionally, scientists have classified these neurons into three main types: skeletal motor neurons, visceral motor neurons, and interneurons. Previous research suggests that there are additional subtypes in these three categories and that some of these subtypes may be more vulnerable to neurodegenerative diseases than others. For example, diseases like spinal muscular atrophy and amyotrophic lateral sclerosis, or ALS, only affect certain types of skeletal muscle neurons.
In the current study, the team used a technique called single-core RNA sequencing to identify 21 subtypes of spinal cord neurons in mice. The results reveal very distinct subtypes, particularly among the motor neurons that control glands and internal organs. The team also found that visceral motor neurons extend higher up the spine than previously known. The authors believe that these motor neurons may be newly discovered subtypes with unknown functions.
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