Dehydration inhibits suckling behavior in weanling rats.

Determined the relation between dehydration and suckling behavior in 567 Sprague-Dawley weanling rats 15, 20, and 23 days of age. After 15 days of age, intra- and extracellular dehydration sharply reduced both the number of Ss that suckled and the amount of milk consumed. Rehydration returned both behaviors to control levels. Thus, during the weaning period, the internal determinants of suckling are not homologous with those of drinking, but are more homologous with those governing feeding. (29 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Some determinants of milk ingestion in suckling rats.

Eight experiments were conducted to examine several possible determinants and controls of milk intake in 10-day-old preweanling Sprague-Dawley rats. Results indicate that while the amount of milk the mother provides is a major determinant of milk consumption, pups will individually adjust their intake in response to certain treatments. Deprived pups ingested more milk than nondeprived littermate controls if given access to enough milk. Intragastric intubations of skimmed milk or distilled water reduced milk intake; heavy cream or isotonic saline did not. Injections of polyethylene glycol or formalin, which produced hypovolemia, increased milk consumption, and hypertonic saline decreased it. Results indicate that preweanling rats are behaviorally responsive to certain changes in body fluids and suggest that milk intake involves more than an invariant reflex. (30 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Fluid intake and behavioral changes in rats associated with the distension of the small and large intestine.

Effects of volumetric distension of the small and the large intestine on rats' behavior were compared. Rats were stimulated by a rubber balloon inserted into chronic isolated intestinal loops prepared from the lower duodenum-upper jejunum and from the upper colon in the same animal. Thresholds of 3 reaction classes (weak, strong, and painful) were not different from each other in the 2 loops. Distension decreased fluid intake in an intensity-dependent way, with weak and painful stimuli being less effective in the large intestine and strong stimuli less effective in the small bowel. Behavioral indexes supported intake data, satiety indexes were similar to each other and changed in time, whereas aversivity indexes differed in the 2 loops and as a function of intensity but not time. The author suggests that mild discomfort is a physiological satiety factor whereas strong and painful stimuli signal danger and induce aversivity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cinnamate uptake by rat small intestine: transport kinetics and transepithelial transfer

Due to their ubiquitous occurrence in the plant kingdom, plant phenolics, including monomeric cinnamic acids, are ingested by man and animals in variable amounts with their natural diets. Recently, Na(+)-dependent saturable transport of cinnamic acid across the brush-border membrane of rat jejunum has been described. It was the aim of the present study to characterize this mechanism in more detail. We therefore determined the transport kinetics of mucosal uptake of radioactively labelled cinnamic acid under various conditions using a short-term mucosal uptake technique. In addition, the transfer of cinnamic acid across the jejunal wall was investigated using everted intestinal sacs. Investigations of the kinetics of cinnamic acid uptake by the mid-jejunal mucosa revealed the involvement of two transport components, a diffusive Na(+)-independent mechanism and a saturable Na(+)-dependent mechanism. The results obtained with everted sacs provided further evidence of the existence of an active Na+ gradient-driven transport of cinnamic acid across the intestinal epithelium. In the presence of Na+, a significant accumulation of cinnamate occurred inside the serosal compartment and this was strongly inhibited by serosal ouabain. A decrease in the extracellular pH stimulated mucosal cinnamate uptake by increasing the apparent affinity (1/km). This may be attributable to the involvement of a transmembrane H+ gradient in Na(+)-dependent cinnamate transport because the protonophore FCCP caused a significant reduction of cinnamate uptake only in the presence of Na+. The kinetics of cinnamate transport in the absence or presence of a surplus of either unlabelled cinnamate or unlabelled butyrate indicates a reduction in the apparent affinity of the Na(+)-dependent mechanism involved in cinnamate uptake. These results may be explained by a modification of the mechanism by the intracellular pH. Additionally, competitive inhibition of cinnamate uptake by substances structurally related to cinnamic acid may also be involved.     

The effect of dexamethasone treatment on the expression of the regulatory genes of ketogenesis in intestine and liver of suckling rats

The influence of the injection of dexamethasone on ketogenesis in 12 day old suckling rats was studied in intestine and liver by determining mRNA levels and enzyme activity of the two genes responsible for regulation of ketogenesis: carnitine palmitoyl transferase I (CPT I) and mitochondrial HMG-CoA synthase. Dexamethasone produced a 2 fold increase in mRNA and activity of CPT I in intestine, but led to a decrease in mit. HMG-CoA synthase. In liver the mRNA levels and activity of both CPT I and mit. HMG-CoA synthase decreased. Comparison of these values with the ketogenic rate of both tissues following dexamethasone treatment suggests that mit. HMG-CoA synthase could be the main gene responsible for the regulation of ketogenesis in suckling rats. The changes produced in serum ketone bodies by dexamethasone, with a profile that is more similar to the ketogenic rate in the liver than that in the intestine, indicate that liver contributes more to ketone body synthesis in suckling rats. Two day treatment with dexamethasone produced no change in mRNA or activity levels for CPT I in liver or intestine. While mRNA levels for mit. HMG-CoA synthase changed little, the enzyme activity is decreased in both tissues.     

Glucose transport in the small intestine of rats following section of the pancreatico-biliary duct]

Decoquinate administered orally in a grain mix at dosages of 0.5, 0.538, 0.7, and 0.8 mg/kg of body weight suppressed oocyst discharge and bloody diarrhea in calves inoculated 3 days later with 100,000 oocysts of Eimeria bovis (experiment 1, n = 12 calves) or with 100,000 oocysts each of E bovis and Eimeria zuernii (experiment 2, n = 16 calves). Doses of 0.1, 0.163, 0.243, 0.3, and 0.362 mg/kg of body weight gave only partial suppression of oocyst discharge and diarrhea. Clinical signs of coccidiosis did not recur for 23 days after the treatment was discontinued.     

How I explore.... The small intestine using double-lumen enteroscopy

A 14-year 4-month-old boy sustained a triplane fracture of the distal radius. Reduction and maintenance of reduction were achieved by closed manipulation and cast. The triplane fracture can occur in areas other than the distal tibia and distal humerus and can be successfully treated nonoperatively.     

Surgery of the small intestine

Although earlier reports describe a poor prognosis for small intestinal surgery in the horse, there is growing evidence that the short-term survival rate can exceed 80%. In addition to advancements in surgery and aftercare, early referral contributes considerably to the improved prognosis. Surgical procedures that restore anatomic and physiologic continuity to close to normal can minimize postoperative complications. Jejunojejunostomy carries a better prognosis than jejunocecostomy, probably because the latter involves anastomosis between two intestinal segments with dissimilar functions. Careful technique can reduce the prevalence of complications, such as postoperative ileus and serosal adhesions.     

Perforations of the small intestine

Six cases of perforation of the small intestine, one secondary to anaphylactoid purpura and five spontaneous, are reported. Ingestion of an iced drink acted as a trigger in two cases. A vascular genesis is put forward to explain the aetiopathogenesis of two cases and it is noted that perforation of this type is present in the final ileal ansa, at the mesenterial margin. In three cases, histology revealed the presence of double refraction crystal. These came from vegetal residues and are probably capable of penetrating from the lumen into the mucosa causing a foreign body reaction, abscess and subsequent perforation. In these cases, perforation occurred in an ansa located further away than the last ileal ansa (about 3 m) and on the mesenterial margin. Intestinal resection and subsequent end-to-end, single layer anastomosis were performed in all cases.     

Ganglioneuroma of the small intestine

The ganglioneuroma is a rare, benign tumor of the small bowel. The clinical symptomatology and morphology of the tumor are presented in detail. The differences in histopathology between ganglioneuroma and eosinophilic granulomatous polyp are discussed. Therapy should be resection of the tumor.     

Influence of ischaemia-reperfusion injury on CD44 expression in rat small intestine

BACKGROUND: CD44 is an adhesion molecule expressed by neutrophils and lymphocytes which is involved in cell-cell and cell-matrix binding. In this study, the effect of ischaemia-reperfusion injury on CD44 messenger RNA (mRNA) and cell surface immunohistochemical expression of CD44 in the rat small intestine was evaluated. METHODS: Wistar rats (n=16) were randomized to either serve as controls (sham surgery) or to be subjected to a standardized ischaemia-reperfusion injury (suprarenal aorta occluded for 1 h followed by 1 h of reperfusion). Standardized segments of jejunum were harvested after ischaemia-reperfusion injury (ischaemic and reperfused samples) to measure the mucosal protein and DNA content, mRNA expression of CD44 and the immunohistochemical expression of CD44. RESULTS: Reperfusion significantly damaged the jejunal mucosa, e.g. mucosal protein content was lower after reperfusion compared with that in the control group (z=-2.31, P=0.02) and the ischaemic samples (z=-2.52, P=001). The expression of cell surface CD44 protein was also significantly decreased after ischaemic injury (z=-1.99, P=0.04); this coincided with a decrease in the amount of cytoplasmic CD44 mRNA within isolated enterocytes (z=-2.31, P=0.02). CONCLUSION: Ischaemia-reperfusion injury decreases the expression of CD44 within the jejunal mucosa. This may contribute to the failure of the gut barrier after such injury.     

Malignant melanoma in the small intestine

A case story of malignant melanoma is presented. The tumour was localised to the jejunum. The symptoms, diagnosis and treatment are described and the pathogenesis is discussed.     

Deprivation of dietary nucleotides decreases protein synthesis in the liver and small intestine in rats

BACKGROUND & AIMS: Dietary nucleotides are reported to influence the growth and functioning of the liver and small intestine. The aim of this study was to examine the mechanism by which nucleotides exert their effects in these tissues by assessing protein synthesis activity and related parameters in the presence or absence of dietary nucleotides. METHODS: Rats were fed a purified diet with or without nucleotides for 10 days. Fractional protein synthesis rate, RNA and DNA concentrations, polysome size distribution, and number of ribosomes were assessed. RESULTS: Fractional protein synthesis rates of the liver and small intestine were lower in the nucleotide-deprived group than in the control group. In the liver, RNA concentration was also lower in the nucleotide-deprived group, but values in the small intestine were similar in the two groups. In the liver, deprivation of nucleotides resulted in a reduction in the number of ribosomes and in polysome breakdown. Protein and DNA concentrations did not vary in the liver; however, the concentration of DNA was lower in the small intestine of the nucleotide-deprived group than in the control group. CONCLUSIONS: Dietary nucleotides can modulate protein synthesis in the liver and small intestine as a result of tissue-specific nucleic acid changes.     

The role of experience in suckling maintenance in albino rats.

In Exp I nipple-attachment behavior in Sprague-Dawley albino rats was disrupted by raising rat pups in isolation from their mother and siblings on the 3rd–5th day after birth. In Exp II nipple attachment was maintained, however, in isolation-reared pups that received, on Days 3 and 4 postnatally, either 6 or 12 opportunities to search for, locate, and attach to the nipples of an anesthetized mother. Suckling remained severely disrupted on Day 5 in pups whose experiences on Days 3 and 4 were restricted to either nipple search alone or nipple attachment without previous search. Findings focus attention on the role of experience in suckling maintenance and suggest that in rats the suckling system is not fully specified at birth. (35 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ontogeny of suckling in rats: Transitions toward adult ingestion.

Studied the suckling behavior of neonatal Sprague-Dawley rats on their own anesthetized mother from the day of birth until after weaning (35 days). Even newborn Ss were capable of nipple attachment without maternal assistance. Before 11–23 days of age, pups deprived of suckling for 22 hrs and nondeprived pups quickly attached to their mother's nipples, sucked, and remained attached to the nipple though no milk delivery occurred. Then behavior underwent at least 3 changes: (a) After 11–23 days of age, latency to attach became considerably elevated in nondeprived pups; (b) a 2nd change in latency occurred at 23–25 days of age, when nondeprived pups no longer even attached to the nipples of anesthetized mothers; and (c) about 14 days of age, deprived pups began to shift from 1 nipple to the next after initial attachment. These developmental changes were seen in other test situations in which pups were placed directly on a nipple and not required to search and when various periods of deprivation were utilized. These transitions were not critically dependent on the onset of visual function or on the pup's experience with food other than mother's milk. Suckling, therefore, in not an unmodified reflex but is an appetitive behavior that undergoes a series of changes during development. These transitions constitute major developmental events in the ontogeny of rat ingestive behavior. (48 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Primary adenocarcinoma of the small intestine

Eighteen cases of primary adenocarcinoma of the small intestine have been reviewed, which demonstrated the relative frequency of symptoms common to this disease. The clinical features, pathology, and treatment of small bowel adenocarcinoma have been presented and the literature reviewed.