Our entire nervous system consists of two main cell types - neurons and glial cells. We could see their coexistence similar to a symbiotic relationship since neurons are required for our entire body system to function, and glial cells take good care of them for it.
The truth is glial cells make up about 90% of the nervous system, and they are extremely important for its proper functioning. We could call them “maintenance cells” because they perform, for example, neuroprotective, metabolic, and homeostatic tasks. Science differentiates central and peripheral glial cells, where central ones are macroglia and microglia, and peripheral ones are typically Schwann cells, satellite cells, and enteric glia.
A typical example of macroglial cells is astrocytes, which are the hot topic of this research.
Astrocytes are necessary, for example, in the modulation of metabolism, extracellular ion concentration, or neurotransmitter levels, and in this instance, the concrete mechanism that astrocytes account for is the exocytosis (=release) of adenosine triphosphate (commonly known as ATP - the “energy molecule”).
The aim was to explore the significance of ATP release in mice models, and the scientists on this journey discovered one protein, which was single-handedly responsible for the proper secretion mechanism function - vesicular nucleotide transporter (Vnut). This transporter’s role is loading ATP into the secretory vesicles, and the deletion of this transporter leads to reduced ATP release without any change in the molecular machinery of exocytosis or total intracellular ATP content. The deletion of Vnut also led to increased anxiety, depressive demeanor, and decreased motivation, especially in females.
These alterations in behavior are associated with significant decreases of the basal extracellular dopamine levels, which (when confirming the low level of dopamine in the subject) demonstrates a key role of astrocytic exocytosis of ATP in anxiety, depressive-like behavior and motivation by regulating the dopamine circuitry. In short, it is possible that one singular protein is responsible for an entire psychological diagnosis.
Resources:
Huang, Q., Lee, H.H., Volpe, B. et al. (2024) Deletion of murine astrocytic vesicular nucleotide transporter increases anxiety and depressive-like behavior and attenuates motivation for reward.
ncbi.nlm.nih.gov Astrocytes
ncbi.nlm.nih.gov Glial cells
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