Distribution of Serotonin-immunoreactive Enterochromaffin Cells in the Gastrointestinal Tract of the Least Shrew (Cryptotis parva)

Abstract

SUMMARY:Serotonin is an important neurotransmitter in the central (CNS) and peripheral (PNS) nervous systems. It is involved in a variety of physiological processes both in the gut and in the CNS. The present study examined the distribution of serotonin containing enterochromaffin cells in the gastrointestinal tract (GIT) of a vomit competent species, the least shrew. These cells were easily recognized by their globular granules stained with the H&E and serotonin immune-positive stain. The immunoreactive enterochromaffin cells (IERCs) were mainly confined to the basal portion of the glandular epithelium and were distributed throughout the shrew stomach, small and large intestine. None was found to be associated with the mucosal epithelial lining. Moreover, their distribution and count varied in different regions of the GIT suggesting specific functions for these regions. The highest concentration of IERCs was found in the colon followed by the Jejunum. Appreciable numbers of IERCs were found in the stomach especially at the esophageo-gastric junction. The gastric location of the IERCs was mainly in the basal portion of the gland. However, some IERCs were associated with the parietal cells of the stomach. Two types of IERCs were observed: One with globular secretory granules in their apical portion of the cytoplasm which were located within the glandular epithelial cells facing the glandular lumen which release their secretions into the lumen; and the second were basally located, facing the lamina propria of the mucosa. Their secretory granules were not distinct in shape, and are most probably paracrine in their mode of secretions.

Basolateral Amygdala Serotonin 2C Receptor Regulates Emotional Disorder-Related Symptoms Induced by Chronic Methamphetamine Administration

“…In the brain, 5-HT regulates emotions, synaptic plasticity, learning, memory, and reward behavior ( Ji and Suga, 2007 ; Hayes and Greenshaw, 2011 ; Meneses and Liy-Salmeron, 2012 ), as it is one of the most vital neurotransmitters. TPH2 is the rate-limiting enzyme for the synthesis of 5-HT in the brain ( Al-Tikriti et al, 2012 ) and is essential for the biosynthesis of 5-HT in the central nervous system. MA enters the brain through the blood-brain barrier and inhibits TPH2 enzyme activity, even when exposure occurs just once ( Haughey et al, 1999 ; Northrop and Nicole, 2015 ).…”

Histomorphology and Immunohistochemistry of the Lower Esophageal Sphincter of the Least Shrew <b><i>(Cryptotis Parva)</i></b>

“…The distribution of 5-HT has been well documented in the gut of several species, including the least shrew [Rattan and Goyal, 1977;Adamson and Campbell, 1988;Barnette et al, 1992;Mohammad-Zadeh et al, 2008;Al-Tikriti et al, 2012]. These studies have shown that serotonin is widely distributed across several regions of the gut; however, its distribution along the GIT can be different in different species.…”

“…In addition, serotonin-containing perikaryon has been found in the myenteric plexuses of the mouse GIT [Hempfling et al, 2012]. The presence of serotonin has also been demonstrated immunohistochemically in different regions of the least shrew GIT mucosa [Al-Tikriti, et al, 2012]. The role of serotonin in the pathophysiology of GIT disorders including emesis and gastroesophageal reflux disease has been well established [Spiller, 2008;Darmani and Ray, 2009;Gershon 2013].…”

“…The endocrine cells, especially the serotonin-producing EC cells, have been studied in the least shrew [Al-Tikriti et al, 2012] and in other species including humans [Strombeck and Harrold, 1985;Kanamori et al, 1989;Saegusa et al, 2011;Gershon, 2013]. 5-HT is involved in the control of sensory and motor functions of the GIT through its interaction with neurons in the myenteric and submucosal plexuses as well as the vagal afferents [Mohammad-Zadeh et al, 2008;Spiller, 2008;Gershon, 2012].…”

MS-Based Metabolomics for the Investigation of Neuro-Metabolic Changes Associated with BDE-47 Exposure in C57BL/6 Mice

“…In the CNS, serotonin regulates mood, appetite, emesis, and migraine. Approximately 90% of the human body's total serotonin is produced by the gastrointestinal enterochromaffin cells located in the colon, mainly used to regulate intestinal movements [29]. Interestingly, serotonin was significantly upregulated with the downregulation of nicotinamide in serum samples (Fig.…”