Afferent vagal stimulation via gastric electrical stimulation alters sympathetic-vagal balance in domestic pigs - a pilot trial

The disturbance of the sympathetic-vagal balance with increasing sympathetic activity and consecutive increase in cytokine release is a major threat in numerous hyperinflammatory syndromes. Therapeutic interventions that modulate the activity in the sympathetic-vagal system are suggested as an effective treatment in these incidences. The purpose of this pilot study was to investigate the effect of electrical stimulation of the gastric wall on sympathetic-vagal balance. German domestic pigs (n=5) were prepared with a modified gastric tube (mGT) for repetitive gastric electrical stimulation (GES). Electrocardiogram was recorded continuously and heart rate variability (HRV) as measure of sympathetic-vagal activity was calculated for three-minute epochs at baseline condition before GES and during GES condition. In comparison to baseline, activity of the autonomic nervous system (ANS) shifted significantly toward increased dominance of vagal activity during GES with a decrease of normalized low frequency (nLF from 58.00 to 25.52) as marker of sympathetic dominance and parallel increase of normalized high frequency (nHF from 41.48 to 74.16) as marker of vagal dominance. During GES, compared to baseline, no difference in heart rate was found. These results indicate that electrical stimulation of the gastric wall may result in shifting the sympathetic-vagal balance toward a parasympathetic predominance.

Autonomic balance determines the severity of COVID-19 courses

COVID-19 has left mankind desperately seeking how to manage dramatically rising infection rates associated with severe disease progressions. COVID-19 courses range from mild symptoms up to multiple organ failure and death, triggered by excessively high serum cytokine levels (IL 1β, IL 6, TNF α, IL 8). The vagally driven cholinergic anti-inflammatory pathway (CAP) stops the action of nuclear factor κB (NF-κB), the transcriptional factor of pro-inflammatory cytokines. Thus, well-balanced cytokine release depends on adequate vagal signaling. Coronaviruses replicate using NF-κB transcriptional factor as well. By degrading the cytoplasmatic inhibitor of NF-κB subunits (IκB), coronaviruses induce unrestricted NF-κB expression accelerating both, virus replication and cytokine transcription.

We hypothesize that CAP detriment due to depressed vagal tone critically determines the severity of COVID-19.