Histochemical characterization of myenteric plexus in domestic fowl small intestine

The myenteric plexus of the domestic fowl (Gallus domesticus) small intestine was studied by means of silver staining, glyoxylic acid-induced fluorescence, the modified Koelle-Friedenwald method for the detection of acetylcholinesterase, NADH-diaphorase techniques and the unlabelled antibody method involving the use of an antiserum raised against GABA conjugated by glutaraldehyde to bovine serum albumin. The majority of the perikarya were in the ganglia, with an average density of 3370 +/- 942 nerve cells/cm2. Cholinesterase-positive and a few GABA-immunoreactive nerve cell bodies were seen in the myenteric ganglia, while fluorescent ganglion cells were not observed. In addition to AChE and GABA-positive nerve fibres, a rich fluorescent network of varicose and nonvaricose nerve fibres was detected, pointing to the presence of an extrinsic aminergic system in the domestic fowl myenteric plexus. Electron microscopic observations on nerve cells, axon profiles and varicosites with various vesicle populations were in good agreement with the histochemical findings.     

Myo-inositol transport in the small intestine of the domestic fowl

• 1.1. Myo-inositol is transported in chicken small intestine by a mediated route with an apparent K_m of 0.1 mM and by a diffusion mechanism.
• 2.2. The mediated route is susceptible to inhibition by sugars, though sugars are not transported by this process, nor is myo-inositol transported by the sugar transport system.
• 3.3. Myo-inositol influx is inhibitable by phlorizin, sulfhydryl reagents, removal of Na⁺ from the incubation medium, and preloaded sugar; it can be stimulated by theophylline.
• 4.4. The ability to absorb this nutrient varies greatly between individual animals.

     

Sterol absorption by the small intestine

PURPOSE OF REVIEW: Cholesterol absorption is a selective process in that plant sterols and other non-cholesterol sterols are absorbed poorly or not at all. Recent research on the sterol efflux pumps adenosine triphosphate-binding cassette transporter G5 and adenosine triphosphate-binding cassette transporter G8 has not only provided an explanation for this selectivity, but also, together with the discovery of a new class of cholesterol absorption inhibitor, has yielded new insights into the mechanisms that potentially regulate the flux of cholesterol across the enterocyte. This review discusses these recent developments and their importance to the regulation of whole body cholesterol homeostasis. RECENT FINDINGS: Adenosine triphosphate-binding cassette transporters G5/8 regulate plant sterol absorption and also the secretion into bile of cholesterol and non-cholesterol sterols. Loss of adenosine triphosphate-binding cassette transporter G5/8 function results in sitosterolemia. Ezetimibe, a novel, potent and selective inhibitor of cholesterol absorption which is effective in milligram doses, lowers plasma plant sterol concentrations in sitosterolemic subjects, thus suggesting that this drug might be inhibiting the activity of a putative sterol permease in the brush border membrane of the enterocyte that actively facilitates the uptake of cholesterol as well as other non-cholesterol sterols. SUMMARY: Intestinal cholesterol absorption represents a major route for the entry of cholesterol into the body's miscible pools and therefore can potentially impact the plasma LDL-cholesterol concentration. The combined use of agents that inhibit the absorption and synthesis of cholesterol provides a powerful new approach to the prevention and treatment of atherosclerosis.     

Histochemical features of the Muscovy duck small intestine during development

We demonstrated for the first time the distribution and morphology of argyrophil and of goblet cells in the mucosa of the small intestine of the Muscovy duck during development using the Grimelius silver staining and alcian blue/periodic acid-Schiff (AB/PAS) staining technique. The argyrophil cells distribution was variable over the length of the small intestine from embryonic day 24 (24E) to post-hatching day 13 (13d). In the villi most argyrophil cells belonged to the open-type, while in the crypts they belonged to the closed-type. In the duodenum the density of argyrophil cells was highest at hatching, while in the jejunum and in the ileum the highest density value was at hatching and 13d. AB/PAS-positive goblet cells appeared on the villi and crypts of the duodenum and jejunum at 30E, and in the ileum at hatching. The density of AB/PAS-positive cells was the highest in the three segments at hatching. The AB-positive cells, compared with the PAS-positive cells, predominated in villi and crypts of the three segments, moreover the rate of AB-positive cells to PAS-positive cells significantly decreased from 30E to 9d. An increase in argyrophil and goblet cells number during the later incubation and at hatching, could indicate the small intestine in that period is being prepared to face a new diet.     

Prolonged changes in hormonal homeostasis after brief circulatory arrest in the small intestine

It has been established that temporary cessation of blood circulation in the rat small intestine induces alterations in the levels of thyroid and glucocorticoid hormones. These alterations are of the wavy character and can be traced up to 2 weeks after the operation that correlates with duration of previously found functional biochemical, and morphological changes.     

Stability and absorption of liposomes with incorporated insulin in the small intestine

Lecithin-cholesterol liposomes with the incorporated insulin were studied in vitro for their stability to the action of some factors of gastrointestinal tract--hydrochloric acid, gastric juice, pepsin, trypsin, bile. A considerable destructive action of bile on liposomes is established. Modification of the lipid composition of liposomes makes it possible to increase their stability to the bile action. Suction of liposomes from the isolated sites of rat small intestine is studied. Insulin from liposomes is established to be sucked most intensive from the initial parts of small intestine. In this case it penetrates into the blood bed not in a free state but in the composition of liposomes.     

Structural changes in the small intestine wall and its lymphatic bed after gastrectomy

Morphologically and histochemically structural changes of the small intestine wall and its lymphatic bed have been studied in 104 dogs after the stomach resection. After the operation an increase in the diameter of the lymphatic capillaries and vessels takes place. Lateral dilatations and protrusions in the capillary walls appear, new anastomoses in all the membranes are formed, they are mostly manifested in the mucous membrane. Histopathological rearrangement in the small intestine wall is demonstrated as edema of the mucous membrane, as plethora of the vessels, as lymphoid infiltration and as changes of the villi forms.     

Morphofunctional changes in the endocrine system of the small intestine after its proximal resection

The influence of 50% proximal resection of the small intestine on the intestinal endocrine system was investigated on white male rats. The quantitative changes of argyrophil and argentaffin cells correlated with their secretory activity changes. The opposite character of secretory function synchronization was revealed on the 7th and 30th days along the length of the small intestine (proximo-distal sinusoid phenomenon). The secretory function normalization of the endocrine system is carried out in the distal and proximal direction along the length of the small intestine.