The understanding of visceral pain pathways is important in recognizing the serotonin relation and influence of it in pain modulation in IBS. Pain regulation pathways in visceral pain include vagal and spinal afferents that project into the CNS, both facilitating and/or inhibiting the sensory transmission to the spinal cord. Specifically, in visceral pain, there is an antinociceptive action of estrogen on the serotoninergic system due to afferent-driven vagal inhibition of the pain. On the other hand, the pro-nociceptive action occurs because of the enhancement of serotonin secretion in the intestinal mucosal mast cells (IMMCs); cells in which estrogen receptors have been found and that have been associated with its degranulation, increasing the visceral motor response and spinal or supraspinal processing of visceral nociception, mainly in IBS. Furthermore, as described previously, the interference of serotonin in pain modulation depends on the receptors, route of administration, type of pain, and influence of other substances on the release of this neurotransmitter.https://scholar.google.com/scholar?hl=hu&as_sdt=0%2C5&q=An+Association+of+Serotonin+with+Pain+Disorders+and+Its+Modulation+by+Estrogens&btnG=