173 — Multiple Lines of Evidence Indicate That Gliotransmission Does Not Occur under Physiological Conditions

This paper is a neuroscience paper, though it doesn’t focus on neurons: Instead, this paper looks at the other white meat: Glial cells.

Gliotransmission is a bit of an open question in neuroscience: Do glia release neurotransmitters in response to chemical or electrical stimuli? And, if so, is this an endogenous response, or is it a result of the experimental environment?

The Journal of Neuroscience publishes “Dual Perspectives” — two papers that seemingly conflict, despite both relying on existing, peer-reviewed research. This paper is one side of one such pair: I’ll read the other tomorrow. (That link won’t work until February 10, 2018!)

Fiacco & McCarthy argue that gliotransmission does not occur under physiological conditions. That last clause is important: They agree that gliotransmission can be induced under laboratory settings or with pharmacological agents, but they maintain that healthy tissue in an intact brain does not experience gliotransmission.

There are a few lines of evidence that suggest that gliotransmision doesn’t occur in healthy brain tissue, and the authors reference a few existing papers that either induce gliotransmission using means not found in the brain — such as mechanical stimulation — or other work which demonstrates that astrocyte Ca²⁺ waves, one commonly cited indication that astrocytes use calcium ion signals for neurotransmission, do not propagate between neurons in healthy forebrain, and instead simply remain within a single cell.

One of the coolest parts of reading this article was getting to see the “Response from Dual Perspectives Companion Authors” section at the end, where Savtchouk and Volterra contest these findings, which has the convenient byproduct of reviewing the findings of the paper in very succinct terms.