Immunocytochemical identification of low-affinity NTS2 neurotensin receptors in parietal cells of human gastric mucosa

Abstract

The biological effects of neurotensin (NT) are mediated by two distinct G protein-coupled receptors, NTS 1 and NTS 2 . Although it is well established that neurotensin inhibits gastric acid secretion in man, the plasma membrane receptor mediating these effects has not been visualized yet. We developed and characterized a novel antipeptide antibody to the carboxy-terminal region of the human NTS 2 receptor. The cellular and subcellular distribution of NTS 2 receptors was evaluated in various human gastrointestinal tissues. Specificity of the antiserum was demonstrated by (1) detection of a broadband migrating at M r 90 000-100 000 in Western blots of membranes from NTS 2 -expressing tissues; (2) cell-surface staining of NTS 2 -transfected cells; (3) translocation of NTS 2 receptor immunostaining after agonist exposure; and (4) abolition of tissue immunostaining by preadsorbtion of the antibody with its immunizing peptide. In the gastrointestinal tract, NTS 2 receptor immunoreactivity was highly abundant in parietal cells of the gastric mucosa, in neuroendocrine cells of the stomach small and large intestine, and in cells of the exocrine pancreas. NTS 2 receptors were clearly located in the plasma membrane and uniformly present on nearly all target cells. The presence of NTS 2 receptors was rarely detected in human tumors. This is the first localization of NTS 2 receptors in human formalin-fixed, paraffin-embedded tissues at the cellular level. The abundant expression of low-affinity NTS 2 receptors on the plasma membrane of human parietal cells provides a morphological substrate for the direct inhibition of gastric acid secretion observed after i.v. administration of neurotensin.

The Physiology of the Gastric Parietal Cell

“…Vagotomy abolishes the antisecretory effect of (Gln4)-neurotensin, which has a glutamine residue at position 4 instead of glutamic acid in the natural form ( 14 ), and neurotensin-binding neurons were identified in rat nodose ganglia ( 198 ), suggesting the remarkable contribution of a vagal reflex. NTS 1 R, which is equally activated by neurotensin and xenin, is distributed in sensory neurons ( 300 ), and NTS 2 R is localized on basolateral membranes of parietal cells in human gastric mucosa ( 342 ). Both neuronal pathways and direct effects on parietal cells likely mediate postprandial antisecretory effects of neurotensin-related peptides.…”

Xenin-25 induces anion secretion by activating noncholinergic secretomotor neurons in the rat ileum

“…Therefore, we have also examined whether xenin-25-evoked Cl Ϫ /HCO 3 Ϫ secretion in the ileum required NTSR1. Furthermore, NTSR2 expression has also been detected on enteroendocrine cells in the stomach and small and large intestine (48). Thus we used NTSR antagonists SR48692 for NTSR1 and NTRC824 for NTSR2, as described in previous studies (29,35).…”

Neurotensin and its high affinity receptor 1 as a potential pharmacological target in cancer therapy

“…NTRS2 expression also occurs in the gastric mucosa, in neuroendocrine cells of the stomach, and the small and large intestine, and in cells of the exocrine pancreas. NTSR2 is rarely detected in human-derived tumors (Schulz et al, 2006). Recently, NTSR2 was found overexpressed in B cell leukemia patient’s cells (Saada et al, 2012), and upregulated in prostate cancer cells luminal phenotype (Swift et al, 2010).…”