Transcytosis of gastric leptin through the rat duodenal mucosa

Leptin is secreted into the gastric juice by epithelial Chief cells and reaches the duodenum in a biologically intact active form. We assessed the possibility that this gastric leptin crosses the intestinal mucosa by transcytosis through enterocytes to reach blood circulation. Endogenous gastric leptin secretion was triggered by cholinergic stimulation. In another set of experiments, recombinant leptin was inserted in vivo into the duodenal lumen. Plasma levels of leptin were assessed by enzyme immunoassay and Western blot, and duodenal tissue was processed for immunocytochemistry. We first observed that leptin was found inside duodenal enterocytes from fed rats but not inside those from fasted ones. Stimulation of gastric secretion by a cholinergic agent led to rapid increases in plasma leptin levels (202 +/- 39%) except when the pylorus was clamped. Insertion of recombinant leptin into the duodenal lumen raised plasma leptin concentrations (558 +/- 34%) quite rapidly, whereas carrier solution without leptin had no effect. The use of FITC-tagged leptin reinforced these results. Light and electron microscopy revealed the cellular compartments involved in its transcytosis, namely, the enterocyte microvilli, the endocytotic vesicles, the Golgi complex, and the basolateral interdigitations. Leptin was also present in the lamina propria, in capillary endothelial cell plasmalemmal vesicles, and in capillary lumina. These results demonstrate that gastric exocrine leptin is internalized by duodenal enterocytes and delivered to the lamina propria and blood circulation. It may thus be able to play important paracrine and endocrine functions for the control of gastric emptying and nutrient absorption.     

Species-related variations in antioxidant components of gastric and duodenal mucosa

Enzymatic and non-enzymatic antioxidant profiles of the gastric and duodenal mucosa of rat, rabbit, cat and pig were investigated and found to exhibit significant variations. Rat gastric and duodenal mucosa exhibited the highest levels of basal glutathione of the various tissues examined. The highest activity of glutathione reductase was found in the gastric and duodenal mucosa of rat as compared with that in these tissues from the other species. The gastric mucosa of cat and pig showed similar activities of glutathione peroxidase, which was significantly lower than those in rat or rabbit gastric mucosa. The activity of this antioxidant enzyme was similar in rat, rabbit and pig duodenal mucosa and lower than that in cat duodenal mucosa. Strong correlations were found between activities of the functionally coupled antioxidant enzymes glutathione peroxidase and glutathione reductase in gastric but not in duodenal mucosa. The activity of superoxide dismutase showed negligible regional or species-related variations in activity.     

Structural changes in the gastric mucosa in experimental hyperthyroidism

Using a structural and functional analysis experiments on rats have shown the morphological substrate of the impaired pepsin secretion in experimental hyperthyroidism. It has been established that enhancement of the proteolytic activity of gastric juice at early times of hyperthyroidism is linked with activation of biosynthetic processes in the chief gastric cells. Under the conditions of prolonged hyperthyroidism, the reduced proteolytic activity of gastric juice is caused by inhibition of both bioenergetic and biosynthetic processes in the chief cells.     

Effect of intermittent normobaric hypoxia on gastric and duodenal mucosa in man]

Clinical and laboratory examinations of 11 patients with peptic ulcer have shown that combined treatment using sessions of intermittent normobaric hypoxytherapy (10% of oxygen in 90% of nitrogen, length of respiration is 7 min., respiration of free air 3 min., such 6 cycles for 1 hour) promotes healing of ulcers, decreases dyspepsic and astheno-neurotic symptoms of disease. The method can be recommended for treating the patients with peptic ulcer and for preventing seasonal acute attacks in patients with relapses of this disease.     

Endocrine cells of the gastric mucosa in patients with duodenal ulcer after vagotomy]

Bioptates of the stomach mucous membrane (SMM) have been investigated in 169 patients suffering from duodenal ulcer (DU). According to the nocturnal gastric secretion test among them there are "hypersecretors" and persons with moderate elevation of acid formation. In conformity with the efficiency of the operative treatment among the patients examined, groups are defined: those with recurrent disease and those recovered after vagotomy. The DU endocrine apparatus undergoes both qualitative and quantitative alterations after vagotomy. When recovery after vagotomy takes place, the number of endocrine cells only slightly exceeds these parameters in the patients with a moderately manifested acid production. These alterations are adaptive. The recurrence of DU in patients with moderately manifested acid production before the operation can be explained by hyperplasia of G-cells. A high degree of hyperplasia of all elements of the endocrine apparatus in the "hypersecretors" can be one of the causes of the DU recurrence. The data about the state of G-, Ec- and EcL-cells before and after vagotomy can be used at prognostication the results of surgical treatment of patients with DU.     

The morphometric and immunohistochemical characteristics of the gastric and duodenal mucosa in systemic lupus erythematosus]

Histological, morphometric, and immunohistochemical studies of biopsy specimens from the mucosa of the body and antral portion of the stomach, the bulb and descending portion of the duodenum were performed in 27 children with systemic lupus erythematosis (SLE) and in 12 with chronic gastroduodenitis. The inflammatory infiltrate from SLE patients was found to contain higher levels of young and mature fibroblasts than that from patients with chronic gastroduodenitis, mature fibroblasts being prevalent. The inflammatory changes in the gastric and duodenal mucosa were ascertained to be associated with the progression of SLE. In exacerbation of SLE, the walls of vessels (arterioles) exhibited immune complexes classified mainly as IgG and, to a lesser degree, as IgM. In remission, the luminescence of the vessels decreased. The serum level of immunoglobins did not correlate with their regional production in the gastric and duodenal mucosa.     

Histochemical findings in the rat gastric mucosa during starvation

Summary The influence of starving on the activity of enzymes of the rat gastric mucosa was investigated by selected histochemical methods. Beside the conventional methods of enzymatic histochemistry the technique of semipermeable membranes was used in the proof of lysosomal enzymes. Dehydrogenases were proved in aqueous and also in gel media with PMS.During the starvation in the parietal cells a marked increase took place in the activity of acid phosphatase, E-600 resistant esterase, less in -glucuronidase. High activity of the lysosomal enzymes in macrophages did not change during starvation. Nor did any changes took place in the activity of alkaline phosphatase in the endothelium of the capillaries. The chief cells in the control and starving animals, in contrast to the human gastric mucosa, did not contain any non-specific esterase. Concerning dehydrogenase, parietal cells with a different activity of these enzymes were observed both in starved and control animals.In the rat gastric mucosa starving induced changes in the activity of the enzymes which mark important organelles of the cells. Thus it is possible to consider the observed histochemical changes as a functional manifestation of morphological damage of cellular structures which are affected during starvation.