Functional and structural changes in the small intestine during experimental hypercholesteremia

Functional and structural changes that occurred in the small intestine and liver of rabbits with alimentary hypercholesterolemia have been studied. Maximal rise of peripheral blood cholesterol after a single exposure to cholesterol was coupled with an increased penetration of chylomicrons and low and very low density lipoproteins from the intestine to the circulation. The decrease of cholesterol excretion along the whole length of the small intestine was accompanied by activation of the release of high density lipoproteins into the blood outflowing from the intestine. The decay of chylomicrons in the liver was restricted during the first days of hypercholesterolemia. Cholesterol concentration in the bile was decreased. The microvessels of the small intestine demonstrated the dilatation of the postcapillary-venular component erythrocyte aggregates and capillarostases.     

Functional changes of the small intestine in over- and undernourished suckling rats support the development of obesity risk on a high-energy diet in later life

To investigate the relationship between early nutritional experience, ontogeny of the small intestinal functions and predisposition to obesity development, the following experimental models of male Sprague-Dawley rats were used: 1) rats in which the quantity of nutrition was manipulated from birth to weaning (day 30) by adjusting the number of pups in the nest to 4 (SL), 10 (NL) and 16 pups (LL) and 2) littermates of SL, NL and LL rats fed either a standard or a hypercaloric diet from days 80 to 135 of age. The overfed SL pups were overweight after day 15 and became permanently obese, whereas the underfed smaller LL pups, due to accelerated growth and enhanced food intake from day 30 to day 35, attained a body fat level that did not differ from normally fed NL rats. Moreover, a significantly increased duodenal and jejunal alkaline phosphatase (AP) activity was found in SL and LL rats and these acquired somatic and intestinal characteristics persisted from weaning throughout life. Eight weeks of high-energy diet feeding elicited a similar pattern of intestinal response in SL and LL rats that was clearly different from NL rats. Despite energy over-consumption in these three groups, both SL and LL rats still displayed enhanced AP activity and showed a significant increase in protein/DNA ratio accompanied with a significant body fat accretion. These results indicate that the postnatally acquired small intestinal changes induced by over- and undernutrition could be involved in the similar predisposition to obesity risk in later life when caloric density of the diet is raised.     

Functional reentry and circus movement arrhythmias in the small intestine of normal and diabetic rats

In a few recent studies, the presence of arrhythmias based on reentry and circus movement of the slow wave have been shown to occur in normal and diseased stomachs. To date, however, reentry has not been demonstrated before in any other part of the gastrointestinal system. No animals had to be killed for this study. Use was made of materials obtained during the course of another study in which 11 rats were treated with streptozotocin and housed with age-matched controls. After 3 and 7 mo, segments of duodenum, jejunum, and ileum were isolated and positioned in a tissue bath. Slow wave propagation was recorded with 121 extracellular electrodes. After the experiment, the propagation of the slow waves was reconstructed. In 10 of a total of 66 intestinal segments (15%), a circus movement of the slow wave was detected. These reentries were seen in control (n = 2) as well as in 3-mo (n = 2) and 7-mo (n = 6) diabetic rats. Local conduction velocities and beat-to-beat intervals during the reentries were measured (0.42 ± 0.15 and 3.03 ± 0.67 cm/s, respectively) leading to a wavelength of 1.3 ± 0.5 cm and a circuit diameter of 4.1 ± 1.5 mm. This is the first demonstration of a reentrant arrhythmia in the small intestine of control and diabetic rats. Calculations of the size of the circuits indicate that they are small enough to fit inside the intestinal wall. Extrapolation based on measured velocities and rates indicate that reentrant arrhythmias are also possible in the distal small intestine of larger animals including humans.     

The therapeutic properties of an alcohol extract of plasma in a combined radiation-thermal lesion

The intravenous injection of an alcoholic plasma extract to mice after the combined exposure to radiation and heat decreases lethality, restores the investigation-and-orientation activities and oxygen consumption, favors the growth of body mass and healing of burns. The antioxidant effect of the extract manifests itself by the decreased rate of formation of lipid peroxidation products in the liver and the suppressed spontaneous and latex-induced chemiluminescence of neutrophils.     

Morphological changes in the small intestine of rats after its temporary exclusion from blood circulation]

The experiments were performed in 56 albino rats (15of them served as a control. The small intestine was excluded from the blood circulation for 45minutes and then pieces of the proximal and distal parts of the intestine were taken forhistological and histochemical study. It was shown that such a term of anemia resulted indeep but reversible changes in the mucous sheath and in the intramural nervous apparatus of thesmall intestine. The state of the organ wall became normal in 15 days after operation.     

Age-related changes in antioxidant enzyme activities in the small intestine and liver from Wistar rats.

The present study was designed to determine age-related changes in intestinal and hepatic antioxidant enzymes including superoxide dismutase (SOD), glutathione peroxidase (GSH-PX), and glutathione-S-transferase (GST), and lipid peroxidation in male Wistar rats (n = 8) aged 2 wk, 2.5 mon, 5 mon, 10 mon, and 23 mon. In the small intestine, cytosolic SOD, GSH-PX activities and lipid peroxidation were not affected by age, but intestinal GST activity was noticeably enhanced as age increased. In particular, intestinal GST activity in 23 mon old rats was 3 times as strong as that in 2 wk old rats. In the liver, the activity of hepatic cytosolic SOD was not affected by age, whereas GSH-PX and GST activities in rats aged 10 mon and 23 mon were much stronger than those in rats aged 2 wk, 2.5 mon, and 5 mon. The increased lipid peroxidation in 2.5 mon and 5 mon old rats was observed when compared with that of other groups. It is therefore concluded from the results presented here that age greatly increases GST activity in the small intestinal mucosae and increasing GSH-PX, GST activities and lipid peroxidation in the liver from male Wistar rats.     

Developmental changes in galactosyltransferase activity in the rat small intestine

During postnatal development, UDP-Gal: GlcNAc(beta 1-4)-galactosyltransferase (4 beta-GT) and UDP-Gal:GalNAc(beta 1-3)-galactosyltransferase (3 beta-GT) activities were increased by 17- and 24-fold, respectively, in the rat small intestine. The injection of cortisone into suckling rats resulted in precocious induction of distal 4 beta- and 3 beta-GT activities by 2.7- and 1.8-fold, respectively. Injection of phorbol-12-myristate-13-acetate (PMA) resulted in precocious induction of distal 3 beta-GT by 2.7-fold. These results suggest that intestinal galactosyltransferase activities are under developmental regulation and can be modified by cortisone and PMA.