A. Sengupta

Esterase inhibitors prevent lysosomal enzyme redistribution in two noninvasive models of experimental pancreatitis

Earlier studies have indicated that lysosomal enzymes such as cathepsin B become redistributed within pancreatic acinar cells during the early stages of both diet- and secretagogue-induced acute pancreatitis. As a result, cathepsin B and digestive zymogens became colocalized within large cytoplasmic vacuoles. As cathepsin B can activate trypsinogen, this colocalization could result in intracellular digestive enzyme activation. The present study investigates the protective effects of gabexate mesilate (FOY) and camostate (FOY 305) on both of these noninvasive models of experimental pancreatitis. These esterase inhibitors prevented the hyperamylasemia, pancreatic edema, and acinar cell vacuolization that characterize secretagogue-induced pancreatitis and the hyperamylasemia and mortality that characterize diet-induced pancreatitis. In addition, FOY and FOY 305 were found to significantly decrease the subcellular redistribution of cathepsin B that occurs in both models. These findings indicate that enzyme activity sensitive to inhibition by FOY and FOY 305 may be critical to the redistribution phenomenon that characterizes both of these models of pancreatitis.

Localization of calcitonin gene-related peptide in human esophageal langerhans cells

Previously undescribed calcitonin gene-related peptide-immunoreactive intraepithelial cells were seen in specimens of esophageal mucosa obtained by biopsy or surgical resection from 14 individuals. These calcitonin gene-related peptide-immunoreactive cells were sparsely seen in normal mucosa but increased markedly in esophagitis. They were inaccessible to routine histological stains, but osmication showed them as dendritic forms resembling Langerhans cells of the skin. Their cytological identity was determined with immunocytochemical tests for human antigenic markers such as Ia, HLA-DR, and OKT6 for Langerhans cells, Leu-M5 and Leu-M3 for intraepithelial macrophages, CD3 and TCR-1 for T-lymphocytes, Leu-14 for B-lymphocytes, S-100 for Merkel cells, and chromogranin for amine precursor uptake and decarboxylation cells. Double localization showed that calcitonin gene-related peptide immunoreactivity colocalized with Ia, HLA-DR, and OKT6 but not with the other markers. These studies show that intraepithelial Langerhans cells in the esophageal mucosa contain calcitonin gene-related peptide, which may serve as an immunomodulator.

Peptidergic innervation of the human esophageal smooth muscle

Studies were performed to define the peptidergic nature of intramural nerves in the human esophagus. Cryosections of uninvolved surgically resected tissues from 14 individuals were studied by immunofluorescence for the localization of 10 neuropeptides. Myenteric neurons showed bombesin-, calcitonin gene-related peptide-, galanin-, substance P-, vasoactive intestinal polypeptide-, leucine-enkephalin-, methionine-enkephalin-, neuropeptide Y-, and somatostatin-like immunoreactivity. Submucous neurons had all the above except neuropeptide Y, methionine-enkephalin, leucine-enkephalin, and bombesin. Both groups of neurons received nerve terminations positive for calcitonin gene-related peptide, galanin, neuropeptide Y, substance P, and vasoactive intestinal polypeptide. Myenteric neurons additionally received terminations positive for neuropeptide Y, methionine-enkephalin, and somatostatin. All muscle layers had varicose fibers that reacted for calcitonin gene-related peptide, galanin, neuropeptide Y, and substance P. Longitudinal and circular muscle received few nerves reactive for leucine-enkephalin, whereas methionine-enkephalin was localized in a few nerve endings in the circular muscle. Somatostatin- and bombesin-reactive nerves occurred in longitudinal muscle. No cholecystokinin-reactive nerves were found. This study extends the results of previous studies and shows the previously undescribed presence of calcitonin gene-related peptide- and galanin-reactive nerves in the human esophagus and identifies neuropeptides that may serve as motor, sensory, and modulatory neurotransmitters of esophageal nerves.

Failure of a potent cholecystokinin antagonist to protect against diet-induced pancreatitis in mice.

The effects of a potent cholecystokinin (CCK) receptor antagonist, L-364,718, on two forms of experimental acute pancreatitis in mice were evaluated. The antagonist prevented the hyperamylasemia, pancreatic edema, and acinar cell vacuolization that followed administration of a supramaximally stimulating dose of the cholecystokinin analogue cerulein. In contrast, the same dose of L-364,718 (1 mg/kg/6h) and an even higher dose (10 mglkg/6 h) failed to prevent the hyperamylasemia, acinar cell necrosis, and mortality that followed administration of a choline-deficient ethionine-supplemented diet. These observations are at variance with those previously reported to follow administration of the relatively weak cholecystokinin antagonist proglumide (Niederau C et al. J Clin Znvest 1986;78: 10.5643). The observations reported in this communication suggest that cholecystokinin does not play an important role in diet-induced pancreatitis and that CCK receptor antagonists are unlikely to be of benefit in the treatment of clinical acute pancreatitis.

Localization of galanin immunoreactivity in the opossum esophagus.

Galanin-like immunoreactivity was studied at 7 levels of the opossum esophagus, lower esophageal sphincter (LES) and adjacent portion of the stomach by indirect immunofluorescence; it was restricted to nervous structures. The majority of myenteric and submucous neurons were galanin-positive and received positive axo-somatic terminations. They also sent out axons staining positively. Galanin-positive fibers and a few atypically located neurons formed a mucous plexus at the bases of mucous glands. Varicose galanin fibers innervated the muscularis mucosae, circular and longitudinal muscle layers, while thick fascicles traversed the muscularis mucosae and circular muscle, possibly interconnecting the myenteric, submucous and mucous plexuses. Galanin-positive fibers did not supply blood vessels. There was no obvious gradient of innervation density along the esophagus, but the sphincter appeared to be more densely innervated than the esophageal body. There was no galanin-positive input to striated muscle. In view of its widespread distribution, this neuropeptide may serve multiple functions in the esophagus.

Mucosal peptidergic innervation of the opossum esophagus and anal canal: a comparison with snout skin

Nerves within and under the esophageal epithelium of the opossum esophagus were investigated morphologically with osmication and immunohistochemically for ten neuropeptides. The structurally similar but functionally diverse epithelia of the anal canal and snout skin, on which no immunohistochemical information exists, were similarly investigated for comparison. Total innervation was estimated from osmication, which revealed intraepithelial nerves in all three tissues in the following order of density: snout skin greater than anal canal greater than esophagus. Calcitonin gene-related peptide and substance P occurred in all three organs. The snout skin had intraepithelial galanin nerves but not vasoactive intestinal polypeptide, while conversely the esophagus and anal canal had vasoactive intestinal polypeptide but not galanin. All peptides found intraepithelially also occurred subepithelially. Calcitonin gene-related peptide, galanin, neuropeptide Y, substance P and vasoactive intestinal polypeptide subepithelial nerves occurred in all the tissues, while gastrin releasing peptide nerves occurred infrequently in the subepithelial regions of the esophagus and anal canal, but not the snout skin. As these epithelia neither secrete nor absorb, their nerves are presumably sensory. The peptides investigated could not account for all intraepithelial nerves demonstrated by osmium. Differences in the innervation of these epithelia may result from their differing sensory requirements.

Effects of hemorrhagic shock, aspirin, and ethanol on secretagogue-induced experimental pancreatitis

SummaryThe effects of hemorrhagic shock, aspirin, and ethanol on the biochemical and morphologic changes of experimental pancreatitis were evaluated. Pancreatitis was induced by infusing rats with a supramaximally stimulating dose (5 µg/kg/h) of caerulein. Hemorrhagic shock was established by removing sufficient blood to reduce mean arterial pressure by 30%, where it was maintained for 30 min. Aspirin (25 mg/kg) and ethanol (2 g/kg) were administered through an orogastric tube at 8-h intervals for 48 h.Hemorrhagic shock did not alter the degree of hyperamylasemia, pancreatic edema, cathepsin subcellular redistribution, or in vitro LDH leakage that characterize this model of pancreatitis. Hemorrhagic shock did, however, worsen the morphologic evidence of pancreatic injury. Administration of aspirin with ethanol did not alter the degree of hyperamy-lasemia, pancreatic edema, or subcellular cathepsin redistribution. Aspirin-ethanol pretreatment also did not alter the morphologic severity of pancreatitis.These observations indicate that hemorrhagic shock worsens the microscopic evidence of pancreatitis induced by supramaximal secretagogue stimulation. In contrast, aspirin-ethanol pretreatment, which might have been expected to increase pancreatic ductal permeability, did not alter the severity of this model of experimental pancreatitis.

HISTOPATHOLOGY OF THE ENTERIC NEUROPATHIES : From Silver Staining to Immunohistochemistry

The gut is abundantly supplied with neurons, extrinsic and intrinsic nerve fibers. Knowledge regarding the structure of the enteric nervous system derives principally from the classic silver-staining methods. Because silver stains do not provide information on the molecular constituents of neurons, these data only facilitate classification and may have diagnostic significance. Studies using histochemistry and immunohistochemistry are now completing the morphologic picture and laying the groundwork for the formulation of therapeutic strategies based upon demonstrable chemical defects in enteric disease.