To clarify, this is from the original Science article linked to by the article at the top of this post:
Thus, enteroendocrine cells are chemosensory cells that activate vagal sensory neurons via release of glutamate (see the figure). Kaelberer et al. hypothesize that synaptic transmission confers precise spatial and temporal information about gut contents. Such sensory feedback could allow neural control of rapid processes that modulate gut physiology, such as muscle contraction, whereas neuropeptides such as CCK are responsible for long-lasting behavioral outputs of gut stimulation, such as satiety (5, 6). A remaining issue is what behaviors or physiological processes rely on subsecond neural signaling from the gut.
It seems those gut-neurons (or whatever they are) serve to inform the brain of the gut's contents.
There is nothing there (or in the rest of that article) to suggest a connection between the gut and migraines.