Back

A Conserved SIFamide Circuit Functions as the Insect Vagus Nerve

Sun, Y.; Wei, Y.; Song, Y.; Li, W.; Wong, K.; Chen, J.; Wu, S.-F.; Zhang, T.; Kim, W. J.

2026-08-26 neuroscience
10.64898/2026.08.23.746484 bioRxiv
Show abstract

The insect functional homolog of the mammalian vagus nerve has remained elusive. Here, we identify the SIFamide (SIFa) peptidergic circuit as this homolog in Drosophila melanogaster. SIFa neurons project the longest axons from the brain to the hindgut ampulla, forming synapses with peripheral SIFa-receptor (SIFaR) neurons originating in the abdominal ganglion. This circuit is functionally plastic: sexual experience enhances synaptic strength at the hindgut, increasing excretion while reducing mating duration to to favor energy conservation and metabolic recovery. Mechanistically, this shift involves octopaminergic/tyraminergic gating and SIFa-mediated modulation of Adipokinetic Hormone (AKH) from the corpora cardiaca. We further uncover a feedback loop in which SIFaR/Allatostatin-A (AstA) neurons project back to the brain, signaling hindgut physiological status to SIFa neurons via AstA-R1. This hindgut projection is conserved across diverse insect orders. Thus, the SIFa-SIFaR circuit constitutes an evolutionarily conserved "insect vagus nerve" that integrates metabolic state and reproductive history to optimize survival strategies.

Matching journals

The top 4 journals account for 50% of the predicted probability mass.

50% of probability mass above

"Similar papers" are the closest papers from that journal in the model's embedding space. They show what the match is built on, but the ranking comes mostly from a classifier over the whole training set, not from these examples alone.