Mapping the effect of the antisecretory factor on GABAA receptor α1 and α6 subunits in cerebellar granule cells in vitro

The Antisecretory Factor (AF) is a protein that can reduce intestinal hypersecretion and various inflammation disorders in vivo. Discovered in many mammalian tissues and plasma, its mechanism of action remains unknown. Interestingly, its induction has been found to counteract vertigo in patients with Méniere's disease. This suggests an inherent ability to control body balance and posture, an activity that may play a role in cerebellar function. Therefore, it may be worthwhile to investigate whether this activity can inhibit neuronal cells involved in cerebellar circuitries and its potential action on enteric nervous system ganglia, which could explain its antisecretory effect in the intestine.

Previously, we studied the role of AF on GABA_A receptors in cerebellar granule cells, taking advantage of electrophysiology and evaluating the effects of the administration of AF-16, an AF peptide. Treatment with AF-16 increased GABA_A receptor responses, especially those containing the α₆ subunit. Here, we performed immunofluorescence experiments by staining α₁ and α₆ subunits before and after incubation with AF-16, analyzed super-resolved images comparing pre- and post-treatment maps and critically examined these experimental results with our previous electrophysiological data to shed light on the mechanisms of action of AF protein on GABA_A receptor subpopulations, specifically the "fast" receptors of α_n β_2/3 γ₂ composition that contain either the α₁ or the α₆ subunit.

The results indicate that the α₆ subunit is redistributed, with a decrease in neurites and an increase in soma. Conversely, the α₁ subunit shows opposite results, with an increase in neurites and a decrease in soma.