Acute hormonal response to glucose, lipids and arginine infusion in overweight cats.

In cats, the incidence of obesity and diabetes is increasing, and little is known about specific aspects of the endocrine control of food intake in this species. Recent data suggest that ghrelin has an important role in the control of insulin secretion and vice versa, but this role has never been demonstrated in cats. Here we aimed to improve our understanding about the relationship between insulin, amylin and ghrelin secretion in response to a nutrient load in overweight cats. After a 16 h fast, weekly, six overweight male cats underwent randomly one of the four testing sessions: saline, glucose, arginine and TAG. All solutions were isoenergetic and isovolumic, and were injected intravenously as a bolus. Glucose, insulin, acylated ghrelin (AG), amylin and prolactin were assayed in plasma before and 10, 20, 40, 60, 80 and 100 min after the nutrient load. A linear mixed-effects model was used to assess the effect of bolus and time on the parameters. A parenteral bolus of glucose or arginine increased insulin and ghrelin concentrations in cats. Except for with the TAG bolus, no suppression of ghrelin was observed. The absence of AG suppression after the intravenous load of arginine and glucose may suggest: (1) that some nutrients do not promote satiation in overweight cats; or that (2) AG may be involved in non-homeostatic consumption mechanisms. However, the role of ghrelin in food reward remains to be assessed in cats.

Postprandial response of plasma insulin, amylin and acylated ghrelin to various test meals in lean and obese cats.

The propensity of diets of different composition to promote obesity is a current topic in feline medicine. The effects of three meals with different protein:fat ratios on hormones (insulin, acylated ghrelin and amylin) involved in the control of food intake and glucose metabolism were compared. Five lean (two females and three males, 28.6 (sd 3.4) % body fat mass (BFM), mean body weight (BW) 4590 g) and five obese (two females and three males, 37.1 (sd 4.1) % BFM, mean BW 4670 g) adult cats were studied. Only BFM differed significantly between obese and lean cats. The cats were fed a high-protein (HP), a high-fat and a high-carbohydrate diet in a randomised cross-over design. Food intake did not differ between cats fed on the different diets, but obese cats consumed significantly more energy, expressed as per kg fat-free mass, than lean cats. After a 6-week adaptation period, a test meal was given and blood samples were collected before and 0, 30, 60 and 100 min after the meal. Baseline concentrations of glucose, amylin and acylated ghrelin were higher in obese cats than in lean cats, and obese cats showed the highest postprandial responses of glucose and amylin. The HP diet led to higher postprandial amylin concentrations than the other diets, indicating a possible effect of amino acids on beta-cell secretion. Postprandial ghrelin concentrations were unaffected by diet composition. The relationship between insulin, amylin and ghrelin secretion and their relevant roles in food intake and glucose metabolism in cats require further study.

Spontaneous hormonal variations in male cats following gonadectomy.

The increased prevalence of obesity after neutering in cats is problematic in veterinary practice. Although many factors seem to be involved, the role of prolactin (PRL) and insulin-like growth factor-I (IGF-I), both implicated in adipose tissue development and glucose intolerance, should be considered. Seven male cats were castrated when 11 months old. Body weight was then recorded for 56 weeks and PRL, IGF-I and leptin assayed for 44 weeks. Body weight increased steadily but only significantly after 36 weeks. It stabilised after 44 weeks, and the cats then gained about 20% of their initial body weight. IGF-I increased rapidly and was significantly higher by week 3. PRL and leptin increased with initial peaks during the eighth and eleventh weeks, respectively. This study confirms that castration rapidly modifies the hormonal balance, partly explaining the body weight increase, and that hormonal changes precede this body weight increase. Hyperleptinaemia is apparently a consequence of excess weight.

Evaluation of association between body size and large intestinal transit time in healthy dogs.

OBJECTIVE: To compare large intestinal transit time (LITT) in dogs of various body sizes and determine whether fecal quality was correlated with LITT. ANIMALS: 6 Miniature Poodles, 6 Standard Schnauzers, 6 Giant Schnauzers, and 6 Great Danes. PROCEDURE: LITT was calculated as the difference between total (TTT) and orocecal transit time (OCTT). Minimum and mean OCTTs were determined by use of the sulfasalazine-sulfapyridine method. Minimum TTT was estimated by use of chromium and ferric oxide as color markers, and mean TTT was calculated from the recovery from feces of ingested colored plastic beads. Fecal moisture content was determined and fecal consistency was scored during the same period. RESULTS: Large-breed dogs had higher fecal moisture content and more watery fecal consistency. No association between body size and OCTT was detected, but there was a positive correlation between body size and mean TTT. Mean LITT increased significantly with body size, from 9.1 +/- 1.1 hours in Miniature Poodles to 39.4 +/- 1.6 hours for Giant Schnauzers. Significant correlations were detected among mean LITT, mean TTT, and fecal scores, whereas no correlation was observed between fecal moisture content and TTT or LITT. CONCLUSIONS AND CLINICAL RELEVANCE: LITT was correlated with fecal consistency in dogs of various body sizes. Mean LITT can be predicted from values for mean TTT in healthy dogs.

Resistant starch modulates in vivo colonic butyrate uptake and its oxidation in rats with dextran sulfate sodium-induced colitis.

We previously demonstrated improvements of colonic lesions due to dextran sulfate sodium (DSS) in rats after 7 d of supplementation with resistant starch (RS) type 3, a substrate yielding high levels of butyrate (C(4)), a colonic cell fuel source. In the present study, we hypothesized that if inflammation is related to decreased C(4) utilization by the colonic mucosa, RS supplementation should restore C(4) use simultaneously with an increase in the amount of C(4) present in the digestive tract. Hence, we compared, in vivo, the cecocolonic uptake of C(4) and its oxidation into CO(2) and ketone bodies in control and DSS-treated rats fed a fiber-free basal diet (BD) or a RS-supplemented diet. Sprague-Dawley rats (n = 60) were used. DSS treatment was performed to induce acute colitis and then to maintain chronic colitis. After cecal infusion of [1-(13)C]-C(4) (20 micro mol in 1 h), concentrations and (13)C-enrichment of C(4), ketone bodies, and CO(2) were quantified in the abdominal aorta and portal vein. Portal blood flow was recorded. During acute colitis, (13)C(4) uptake and (13)CO(2) production were lower in DSS rats than in controls. During chronic colitis, DSS rats did not differ from controls. After 7 d of chronic colitis, RS-DSS rats exhibited the same C(4) uptake as BD-DSS rats in spite of higher C(4) cecocolonic disposal. After 14 d, C(4) uptake was higher in RS-DSS than in BD-DSS rats. Thus, the increased utilization of C(4) by the mucosa is subsequent to evidence of healing and appears to be a consequence rather than a cause of this RS healing effect.

Influence of age and body size on orocecal transit time as assessed by use of the sulfasalazine method in healthy dogs.

OBJECTIVE: To compare orocecal transit time (OCTT) as assessed by use of the sulfapyridine appearance time in plasma after oral administration of sulfasalazine in dogs of varying age and body size and determine whether OCTT correlates with fecal quality. ANIMALS: 6 Miniature Poodles (MP), 6 Standard Schnauzers (SS), 6 Giant Schnauzers (GS), and 6 Great Danes (GD). PROCEDURE: Determinations of OCTT were made at 12, 22, 36, and 60 weeks of age. Dogs were fed sulfasalazine mixed with a meal. Blood samples were then collected for 6 hours. The OCTT was the time from ingestion of the meal to detection of sulfapyridine in plasma. Fecal moisture content and consistency were recorded during the same periods. RESULTS: Mean OCTT decreased during growth of GS and GD dogs. No correlation was found between OCTT and fecal variables during growth in the 4 breeds. Effect of body size was observed at 12 and 22 weeks of age, with a longer OCTT in GS and GD than in MP and SS dogs. Similar OCTTs were observed at 36 and 60 weeks of age in all breeds, although GS and GD dogs had poorer fecal quality during those periods. CONCLUSIONS AND CLINICAL RELEVANCE: An effect of age on OCTT was observed only in large-breed dogs, with longer transit times in puppies (12 weeks old) than in adults (60 weeks old). Mean OCTT is not correlated with body size in adult dogs. No relationship was detected between OCTT and fecal variables in healthy dogs.

Restoration of the integrity of rat caeco-colonic mucosa by resistant starch, but not by fructo-oligosaccharides, in dextran sulfate sodium-induced experimental colitis.

Butyrate is recognised as efficient in healing colonic inflammation, but cannot be used as a long-term treatment. Dietary fibre that produces a high-butyrate level when fermented represents a promising alternative. We hypothesised that different types of dietary fibre do not have the same efficiency of healing and that this could be correlated to their fermentation characteristics. We compared short-chain fructo-oligosaccharides (FOS) and type 3 resistant starch (RS) in a previously described dextran sulfate sodium (DSS)-induced colitis model. Seventy-two Sprague-Dawley rats received water (control rats) or DSS (50 g DSS/l for 7 d then 30 g DSS/l for 7 (day 7) or 14 (day 14) d). The rats were fed a basal diet (BD), or a FOS or RS diet creating six groups: BD-control, BD-DSS, FOS-control, FOS-DSS, RS-control and RS-DSS. Caeco-colonic inflammatory injuries were assessed macroscopically and histologically. Short-chain fatty acids (SCFA) were quantified in caeco-colon, portal vein and abdominal aorta. At days 7 and 14, caecal and distal macroscopic and histological observations were improved in RS-DSS compared with BD-DSS and also with FOS-DSS rats. Caeco-colonic SCFA were reduced in FOS-DSS and RS-DSS groups compared with healthy controls. The amount of butyrate was higher in the caecum of the RS-DSS rats than in the BD-DSS and FOS-DSS rats, whereas distal butyrate was higher in FOS-DSS rats. Partially explained by higher luminal levels of SCFA, especially butyrate, the healing effect of RS confirms the involvement of some types of dietary fibre in inflammatory bowel disease. Moreover, the ineffectiveness of FOS underlines the importance of the type of dietary substrate.

Influence of age and body size on intestinal permeability and absorption in healthy dogs.

OBJECTIVE: To evaluate effects of age and body size of dogs on intestinal permeability (unmediated diffusion) as measured by the ratio of urinary lactulose to L-rhamnose (L:R) and absorption (carrier-mediated transport) as measured by the ratio of urinary D-xylose to 3-O-methyl-D-glucose (X:MG) and to determine whether these variables correlated with fecal quality. ANIMALS: 6 Miniature Poodles, 6 Standard Schnauzers, 6 Giant Schnauzers, and 6 Great Danes. PROCEDURE: A solution that contained lactulose and rhamnose or xylose and 3-O-methyl-D-glucose was administered orally to dogs that were 12, 22, 36, and 60 weeks old. Urine was collected 6 hours later, and urinary L:R and X:MG were calculated. Fecal moisture and scoring were recorded during the same periods. RESULTS: Age and breed did not affect intestinal absorption, and we did not detect a relationship between X:MG and fecal variables. In contrast, we detected significant effects of age and body size on intestinal permeability. Puppies (12 weeks old) and large dogs had higher intestinal permeability than adult (60 weeks old) and small dogs. The increased intestinal permeability in large dogs was associated with lower fecal quality as indicated by the significant positive correlations between L:R and fecal moisture (r, 0.61) and L:R and fecal scores (r, 0.86) in adult dogs. CONCLUSIONS AND CLINICAL RELEVANCE: These results indicate that age and body size should be considered when assessing intestinal permeability by use of the L:R urinary excretion test in dogs. High intestinal permeability could be a possible cause of poor fecal quality in large dogs.

Influence of age and body size on gastrointestinal transit time of radiopaque markers in healthy dogs.

OBJECTIVE: To compare gastric emptying time, small-intestinal transit time (SITT), and orocecal transit time (OCTT) of radiopaque markers in dogs varying in age and body size and to determine whether fecal variables (ie, consistency and moisture content) are related to gastrointestinal tract transit times in dogs. ANIMALS: 24 eight-week-old female puppies, including 6 Miniature Poodles, 6 Standard Schnauzers, 6 Giant Schnauzers, and 6 Great Danes. PROCEDURE: Gastrointestinal tract transit time experiments were performed at 12, 22, 36, and 60 weeks of age. Dogs were fed 30 small radiopaque markers mixed with a meal. Abdominal radiographs were taken. The time at which 50% of the markers had left the stomach (T50) and the time at which the first marker reached the colon were calculated. Fecal moisture content and scoring on the basis of fecal consistency were recorded during the same periods. RESULTS: Puppies had a shorter mean T50 than adults, and mean OCTT decreased significantly only during growth of large-breed dogs. However mean fecal moisture content significantly increased with age, except in Giant Schnauzers. No effect of body size on T50 was found regardless of age, and no difference was observed between OCTT of small- and large-breed adult dogs. The effect of age on the mean SITT was not significant for any breed. However, a strong positive correlation was recorded between body size and fecal moisture content (r2 = 0.77) or fecal scores (r2 = 0.69) in adult dogs. CONCLUSIONS AND CLINICAL RELEVANCE: Age affects T50 in small- and large-breed dogs and OCTT in large-breed dogs. However, body size does not affect T50 or OCTT. A relationship does not exist between gastrointestinal tract transit time and fecal variables in healthy dogs.

Predominance of caecal injury in a new dextran sulphate sodium treatment in rats: histopathological and fermentative characteristics.

OBJECTIVES: Cyclic administrations of dextran sulphate sodium (DSS) alternating with distilled water usually induce chronic colitis after a few weeks. In order to obtain stable chronic colitis (without recovery or relapse) in a few days, a new continuous DSS treatment was tested and characterized. Short-chain fatty acids (SCFAs), which remain poorly documented in experimental colitis, were also investigated. METHODS: Thirty-six Sprague-Dawley rats were treated with 5% DSS for 7 days (DI) followed by 3% DSS for 7 days (DM) or 14 days (DF). Control rats received only water. Inflammatory injuries in the caecum and the colon were assessed by macroscopic (colon length, caecum weight, damages score) and histological parameters. SCFAs (acetate, propionate, butyrate) were quantified individually in caecal, proximal and distal contents. RESULTS: Macroscopic and histological observations revealed that this continuous DSS treatment induced acute inflammation (DI) followed rapidly by chronic active colitis. The latter was uncommonly predominant in the caecum and the distal colon, and was also associated with some fermentative disturbances. Caecal SCFA concentrations decreased with DSS at DI and DM. The molar ratio of caecal butyrate increased with DSS. Acetate decreased in the colon while propionate increased. CONCLUSION: This new DSS treatment is able to induce in a few days stable chronic inflammation with caecal and distal predominant injuries, and mild fermentative caeco-colonic alterations. This model could contribute to the study of potential anti-inflammatory effects of prebiotics.

Rate of carbon dioxide production and energy expenditure in fed and food-deprived adult dogs determined by indirect calorimetry and isotopic methods.

OBJECTIVE: To evaluate energy expenditure (EE) in dogs by estimating rate of CO2 production (rCO2). ANIMALS: 15 Beagles. PROCEDURE: Food was withheld for 24 hours, and all dogs received an IV infusion of 13C sodium bicarbonate for 8 hours. Breath samples were collected before infusion and at 30-minute intervals from 4 to 8 hours, and 13C enrichment in breath CO2 was measured, using gas chromatography-isotopic ratio mass spectrometry. Food was withheld from 6 dogs, and rCO2 and O2 consumption were measured, using a conventional indirect calorimeter. The CO2 production and O2 consumption were measured by use of indirect calorimetry in 6 other fed dogs that were injected with 2H2O and H2(18)O. Blood samples were collected before tracer injection, 4 hours later, and on days 4, 7, and 11. Deuterium and 18O enrichments in plasma water were determined. RESULTS: Mean rCO2 measured by indirect calorimetry was 516 +/- 34 and 410 +/- 16 micromol/kg(0.75)/min in 6 fed and 6 food-deprived dogs, respectively. The rCO2 calculated from 13C-bicarbonate dilution was 482 +/- 30 micromol/kg(0.75)/min. Mean rCO2 determined by use of the double-labeled water method was 1,036 +/- 46 mmol/kg(0.75)/d. Mean energy expenditure calculated from rCO2 determined by infusion of 13C bicarbonate, indirect calorimetry in fed and food-deprived dogs, and infusion of double-labeled water was 386 +/- 39, 379 +/- 25, 338 +/- 14, and 552 +/- 25 kJ/kg(0.75)/d, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Energy expenditure calculated by indirect calorimetry in unfed dogs can be considered representative of basal metabolic rate.