Fig. 1.

Gut microbiota-host interaction. Schematic representing the different ways of interaction between the microbiota and host. Painful stimuli sensed by nociceptors expressed at the nerve terminations project signals onto spinal nociceptive neurons located in the lateral neck of the dorsal horn of the spinal cord, which convey information to supraspinal centers. Here, the signal reaches several brain areas such as the thalamus, hypothalamus, limbic system, and cortex, which in concert code the afferent information and generate an efferent signal back to the periphery. The microbiota, which resides in the lumen of the gastrointestinal tract, can influence several factors involved in pain perception and its signaling such as the vagus nerve, cytokine production, corticosterone secretion, short chain fatty acids (SCFAs), and microbial metabolite release