Histochemically Demonstrable Enzymes in the Organs of the Digestive System of the Newborn Rat

Circadian rhythms of oxidoreductases in the rat gastric mucosa. Histochemical study

Examination of selected oxidoreductases (succinate dehydrogenase, mitochondrial glycerol-3-phosphate dehydrogenase, lactate dehydrogenase, NADH tetrazolium reductase) in the rat gastric mucosa revealed diurnal fluctation of enzyme activities with the most marked manifestation in succinate dehydrogenase. The maximum enzymatic activity found at 18.00 h and 24.00 h) points to the highest oxidoreductase capacity in the parietal cells just at the time when a rat usually expresses spontaneously the highest interest in food intake. The high activity of succinate dehydrogenase and other enzymes at that time is very likely the expression of a "fixed" metabolic adaptation of the parietal cells to the elevated production of hydrochloric acid, in connection with its role in the digestion of food in the stomach. The low enzymatic activity of most rat parietal cells during the day may represent the picture of "a resting afunctional".

Influence of starving on the rat gastric mucosa -- light and electron microscopical findings

The histology and ultrastructure of the rat gastric mucosa were investigated during 168 hours of starvation. An increased desquamation of individual foveolar cells was found. In the preserved cells of the foveolae, the content of the PAS positive mucosubstances did not change during starvation, and no changes took place in the appearance and in the amount of the mucous granules at the electron microscopic investigation. The number of lipid droplets increased in the mucous foveolar cells within 24 and 48 hours. During starvation the mitochondria (mainly in the parietal cells) were enlarged and contained rare mitochondrial cristae. Some mitochondria were distintegrated and removed by lysosomes. The number of lysosomes (mainly cytosergresomes) was markedly increased n parietal cells. A collapse of the intracellular canaliculi occurred as well as a narrowing in the tubulovesicular profiles. In chief cells the profiles of the granular endoplasmic reticulum and Golgi apparatus were reduced. It was shown that the ultrastructural changes induced by starvation can be interpreted functionally in changed histochemical parameters of the gastric mucosa.

Histochemical findings in the rat gastric mucosa during starvation

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 beta-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 dehydrogenases, 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.

Histochemical localization of enzymes in the normal rat gastric mucosa using the technique of the semipermeable membranes and the other methods

In the paper we observed histochemically the distribution and activity of 16 enzymes in the normal rat gastric mucosa. The lysosomal enzymes were demonstrated by the method of semipermeable membranes (LOJDA 1972). At the proof of dehydrogenases aqueous and gel media were used. The parietal cells of the gastric mucosa contained a moderate activity of acid phosphatase, E-600 resistant esterase, and only a very slight activity of beta-glucuronidase and N-acetyl-beta-D-glucosaminidase. The macrophages of the interstice contained a high activity of beta-glucruonidase, acid phosphatase, E-600 resistant esterase and a low activity of N-acetyl-beta-D-glucosaminidase. The chief cells of the rat gastric mucosa, in contrast to the human, did not contain nonspecific esterase and also in them acid phosphatase was mostly lacking. The alkaline phosphatase was found only in the endothelium of the capillaries of the gastric mucosa. The parietal cells contained high activities of succinate dehydrogenase, alpha-glycerophosphate dehydrogenase, beta-hydroxybutyrate dehydrogenase, NADH tetrazolium reductase, a lower activity of NADPH tetrazolium reductase, as well as other soluable dehydrogenases. At the examination of dehydrogenases using aqueous as well as gel media with PMS during optimal short incubation periods, we found more and less active forms of parietal cells. The different oxidoreductase capacity of parietal cells in normal rat gastric mucosa can point to their unequal-functional load at the production of hydrochloric acid. The findings obtained are compared with the findings in older papers concerning different experimental animals and with the distribution of enzymes in the human gastric mucosa.