Activation of 5-HT₄ receptors facilitates neurogenesis of injured enteric neurons at an anastomosis in the lower gut

Abstract

Two-photon microscopy (2PM) can enable high-resolution deep imaging of thick tissue by exciting a fluorescent dye and protein at anastomotic sites in the mouse small intestine in vivo. We performed gut surgery and transplanted neural stem cells (NSC) from the embryonic central nervous system after marking them with the fluorescent cell linker, PKH26. We found that neurons differentiated from transplanted NSC (PKH [+]) and newborn enteric neurons differentiated from mobilized (host) NSC (YFP [+]) could be localized within the granulation tissue of anastomoses. A 5-HT4-receptor agonist, mosapride citrate (MOS), significantly increased the number of PKH (+) and YFP (+) neurons by 2.5-fold (P<0.005). The distribution patterns of PKH (+) neurons were similar to those of YFP (+) neurons. On the other hand, the 5-HT4-receptor antagonist, SB-207266 abolished these effects of MOS. These results indicate that neurogenesis from transplanted NSC is facilitated by activation of 5-HT4-receptors. Thus, a combination of drug administration and cell transplantation could be more beneficial than exclusive cell transplantation in treating Hirschsprung's disease and related disorders including post rectal cancer surgery. The underlying mechanisms for its action were explored using immunohistochemistry of the longitudinal mouse ileum and rat rectal preparations including an anastomosis. MOS significantly increased the number of new neurons, but not when co-administered with either of a protein tyrosine kinase receptor, c-RET two inhibitors. The c-RET signaling pathway contributes to enteric neurogenesis facilitated by MOS. In the future, we would perform functional studies of new neurons over the thick granulation tissue at anastomoses, using in vivo imaging with 2PM and double transgenic mice expressing a calcium indicator such as GCaMP6 and channelrhodopsin.

Localization of the 5‐hydroxytryptamine 4 receptor in equine enteric neurons and extrinsic sensory fibers

“…Growing evidence indicates that 5‐HT 4 stimulation enhances development, survival, and neurogenesis of enteric neurons and 5‐HT 4 agonists facilitate neurogenesis from transplanted stem cells in intestinal anastomosis . Thus, 5‐HT 4 agonists may have a neuroregenerative potential that can be useful to treat horses subjected to colic surgery.…”

Intestinal Microbiota Shapes Gut Physiology and Regulates Enteric Neurons and Glia

“…The concept of neurogenesis in the brain of mammals in specific 412 regions has now been widely accepted [62], however, this process within enteric neurons has been largely studied in vitro [61,63,64]. Only recently has enteric neurogenesis been demonstrated in an in vivo setting, with either healthy animals [43] or under conditions of inflammation or injury [44,61,63,65]. However, there are still many questions on how enteric neurogenesis is regulated and to what extent the microbiota contributes to it.…”

Intestinal Microbiota Shapes Gut Physiology and Regulates Enteric Neurons and Glia

“…The concept of neurogenesis in the brain of mammals in specific regions has now been widely accepted [62], however, this process within enteric neurons has been largely studied in vitro [61,63,64]. Only recently has enteric neurogenesis been demonstrated in an in vivo setting, with either healthy animals [43] or under conditions of inflammation or injury [44,61,63,65]. However, there are still many questions on how enteric neurogenesis is regulated and to what extent the microbiota contributes to it.…”