Age influences on intestinal sugar absorption

Quinidine, but not eicosanoid antagonists or dexamethasone, protect the gut from platelet activating factor-induced vasoconstriction, edema and paralysis

Intestinal circulatory disturbances, atony, edema and swelling are of great clinical relevance, but the related mechanisms and possible therapeutic options are poorly characterized, in part because of the difficulties to comprehensively analyze these conditions. To overcome these limitations we have developed a model of the isolated perfused rat small intestine where all of these symptoms can be studied simultaneously. Here we used this model to study the role of eicosanoids, steroids and quinidine in platelet-activating factor (PAF)-induced intestinal disorders. A vascular bolus of PAF (0.5 nmol) triggered release of thromboxane and peptidoleukotrienes into the vascular bed (peak concentration 35 nM and 0.8 nM) and reproduced all symptoms of intestinal failure: mesenteric vasoconstriction, translocation of fluid and macromolecules from the vasculature to the lumen and lymphatics, intestinal edema formation, loss of intestinal peristalsis and decreased galactose uptake. All effects of PAF were abolished by the PAF-receptor antagonist ABT491 (2.5 μM). The COX and LOX inhibitors ASA and AA861 (500 μM, 10 μM) did not exhibit barrier-protective effects and the eicosanoid antagonists SQ29548 and MK571 (10 μM, each) only moderately attenuated the loss of vascular fluid, the redistribution to the lumen and the transfer of FITC dextran to the lumen. The steroid dexamethasone (10 μM) showed no barrier-protective properties and failed to prevent edema formation. Quinidine (100 μM) inhibited the increase in arterial pressure, stabilized all the intestinal barriers, and reduced lymph production and the transfer of FITC dextran to the lymph. While quinidine by itself reduced peristalsis, it also obviated paralysis, preserved intestinal functions and prevented edema formation. We conclude that quinidine exerts multiple protective effects against vasoconstriction, edema formation and paralysis in the intestine. The therapeutic use of quinidine for intestinal ailments deserves further study.

Effects of age and reproductive stage on certain serum biochemical parameters of chios sheep under greek rearing conditions

The aim of the present study was to determine the normal ranges of the most commonly used serum biochemical parameters of sheep reared under Greek breeding conditions, as well as to test for the effects of the age and reproductive status of the animals on the normal values of these parameters. In total, 200 clinically healthy Chios sheep from 10 farms were used in the experiment. For the determination of the effect of age 150 sheep were assigned in three groups. Group A consisting of 50 lambs aged 2-6 months (mean +/- SD: 4.15 +/- 1.08), group B of 50 non-pregnant ewes into lactation aged 1-3 years (mean +/- SD: 2.12 +/- 0.86) and group C of 50 non-pregnant ewes into lactation aged more than 3 years (mean +/- SD: 5.98 +/- 1.66). For evaluating the effect of reproductive status 50 pregnant ewes in dry period were used, 15-30 days before the expected day of lambing (group D), along with the 100 non-pregnant ewes into lactation of groups B and C (group E). Blood sampling was performed once, in dry ewes from December to January, and in lambs and lactating ewes from March to May. The results showed that of the 14 biochemical parameters determined in serum, six were significantly affected by the age and eight by the reproductive stage of the animals.

Changes in the levels of enzymes which modulate the antioxidant balance occur during aging and correlate with cellular damage

Oxidative metabolism produces a flux of superoxide anions that must be removed from the cellular environment if the cell is to survive. The levels of antioxidant enzyme involved in the elimination of superoxide anions and/or hydrogen peroxide were investigated in an attempt to correlate any changes in the levels of these enzymes during aging with changes in free radical mediated cellular damage. Cu/Zn superoxide dismutase (Sod1), glutathione peroxidase (Gpx1) and catalase levels were measured in a number of organs during murine aging. Sod1 enzyme activity rose during aging in all organs studied, while the levels of both Gpx1 and catalase showed organ specific profiles. Both organs in which lipid peroxidation damage (which was used as a marker of free radical mediated damage) increased with age, namely the brain and small intestine, also showed a significant increase in the ratio of Sod1 to Gpx1 enzyme activity. In organs where either the ratio of Sod1/Gpx1 activity or Sod1/catalase levels (in the lung only) ratios were maintained during aging, no increased lipid peroxidation damage was detected. In the lung where Sod1/Gpx1 ratio did increase, Sod1/catalase remained constant and this was able to provide protection during aging. Thus our data shows that alterations in the balance between first and second steps of the antioxidant pathway correlate with cellular damage, and that this may contribute to the aging changes seen in some organs.

Manipulation of gastrointestinal nutrient delivery in livestock

Discussed herein are the constraints of nutrient delivery from the gastrointestinal tract that are placed on postabsorptive synthetic processes in highly selected strains of domestic livestock or livestock treated with growth promotants exogenously or via transgenic manipulation. Emphasis is placed on the discussion of recent advances in the knowledge of the regulation and manipulation of digestion and the absorption by the intestinal epithelium. Slaframine, a muscarinic exocrine secretagogue with a high affinity for the gastrointestinal tract, and epidermal growth factor may have practical potential for the manipulation of digestion and absorption, respectively. Special consideration is given to energetic considerations that must accompany any manipulation of gastrointestinal function. Down-regulation and up-regulation of mechanisms must be equally considered as this area is explored further.

Effect of aging on glycogen synthesis in liver of starved-refed rats

Glycogen content in the livers of young, adult and old rats starved for 40 h and refed with a standard diet for 1, 2 or 4 h was determined. In the fed animals the amount of liver glycogen was similar in all the age groups. Fasting depleted liver glycogen almost completely. Chow refeeding led to glycogen synthesis in the livers of young and adult rats; however, glycogen deposition in the livers of old animals was delayed by 1 h. The amount of liver glycogen replenished in the rats refed for 4 h was similar in all the age groups. Plasma glucose concentrations were similar in all age groups of the fed, starved and refed rats. The mechanisms of age-dependent delay of glycogen synthesis in the liver of starved-refed rats are discussed.