Results suggest retrieval of cellular powerplants via an energy feedback loop sustains communication — ScienceDaily
Our thoughts, feelings, and movements are controlled by billions of neurons talking to each other at trillions of specialized communication points called synapses. In an in-depth study of neurons grown in laboratory petri dishes, National Institutes of Health researchers discovered how the chattiest of some synapses find the energy to support intense conversations thought to underlie learning and memory. Their results, published in Nature Metabolism, suggest that a series of chemical reactions control a feedback loop that senses the need for more energy and replenishes it by recruiting cellular powerplants, called mitochondria, to the synapses. The experiments were performed by researchers in a lab led by Zu-Hang Sheng, Ph.D., at the NIH’s National Institute of Neurological Disorders and Stroke (NINDS).
The team studied synapses that use the neurotransmitter glutamate to communicate. Communication happens when a packet of glutamate is released from presynaptic boutons which are tiny protrusions that stick out, like beads on a string, of long, wiry parts of neurons called axons. Previously, Dr. Sheng’s team showed that synaptic communication is an energy-demanding process and that mitochondria traveling along axons can control signals sent by boutons. Boutons that had mitochondria sent stronger and more consistent signals than those that were missing powerplants. The difference was due to higher energy levels produced by the mitochondria in the form of ATP.
In this study, led by Sunan Li, Ph.D., a post-doctoral fellow at NINDS, the team investigated what happens when boutons undergo intense communication thought to underlie learning and memory. They found that this type of signaling quickly dropped energy levels at boutons. These changes triggered a series of chemical reactions controlled by an energy sensor called AMP-activated protein kinases (AMPK) that ultimately led to the rapid recruitment of mitochondria to the boutons. Genetically blocking or chemically interfering with this