Circulating direct infusion MS and NMR metabolomic profiles of post-gonadectomy kittens with or without additional dietary choline supplementation

Choline is beneficial for energy metabolism and growth in various species. Choline may work similarly in kittens at risk of obesity. Direct infusion MS (Di-MS) and NMR spectroscopy were used to investigate the metabolomic signatures of kittens supplemented with or without additional dietary choline for 12 weeks. Fifteen intact male kittens consumed a base diet (3310 mg choline/kg DM) to their daily metabolisable energy requirement (DER) over an 11-week acclimation. Kittens were gonadectomised and assigned, based on body weight, to the base diet (CONTROL, n 7) or the base diet with 300 mg/kgBW0·75 additional choline as choline chloride (CHOLINE, n 8) and offered three times their individual energy requirement divided into three meals. At weeks −1 and 12, fasted blood was sampled and serum analysed for 130 metabolites via Di-MS and fifty-one metabolites via NMR spectroscopy. Changes in fasted metabolites were assessed using a repeated-measures GLIMMIX procedure with time and group as fixed effects, and time as a repeated measure. Metabolites of one-carbon metabolism and lipids increased, and medium-chain acyl carnitines decreased from week −1 to 12 for CHOLINE (P < 0·05), but not CONTROL (P > 0·05). Increases in amino acid, biogenic amine and organic compound concentrations were observed in both groups (P < 0·05). The results suggest impacts of dietary choline at greater intakes than currently recommended on one-carbon metabolism and fatty acid oxidation, and these may promote healthy growth in post-gonadectomy kittens.

Dose-response relationship between dietary choline and serum lipid profile, energy expenditure, and respiratory quotient in overweight adult cats fed at maintenance energy requirements

Choline is an essential nutrient linked to hepatic lipid metabolism in many animal species, including cats. The current study investigated the serum lipid profiles, serum liver enzymes, respiratory quotients, and energy expenditures of overweight cats fed maintenance diets, in response to graded doses of supplemental dietary choline. Overweight (body condition score [BCS]: ≥6/9) adult male neutered cats (n = 14) were supplemented with five choline chloride doses for 3-wk periods, in a 5 × 5 Latin square design. Doses were based on individual body weight (BW) and the daily recommended allowance (RA) for choline (63 mg/kg BW0.67) according to the National Research Council. Doses were control (no additional choline: 1.2 × RA, 77 mg/kg BW0.67), 2 × RA (126 mg/kg BW0.67), 4 × RA (252 mg/kg BW0.67), 6 × RA (378 mg/kg BW0.67), and 8 × RA (504 mg/kg BW0.67). Choline was top-dressed over the commercial extruded cat food (3,620 mg choline/kg diet), fed once a day at maintenance energy requirements (130 kcal/kgBW0.4). Body weight and BCS were assessed weekly. Fasted blood samples were taken and indirect calorimetry was performed at the end of each 3-wk period. Serum was analyzed for cholesterol, high-density lipoprotein cholesterol (HDL-C), triglycerides, non-esterified fatty acids, glucose, creatinine, blood urea nitrogen (BUN), alkaline phosphatase (ALP), and alanine aminotransferase. Very low-density lipoprotein cholesterol (VLDL) and low-density lipoprotein cholesterol were calculated. Data were analyzed via SAS using proc GLIMMIX, with group and period as the random effects, and treatment as the fixed effect. Statistical significance was considered at P < 0.05. Body weight and BCS did not change (P > 0.05). Serum cholesterol, HDL-C, triglycerides, and VLDL increased with 6 × RA (P < 0.05). Serum ALP decreased with 8 × RA (P = 0.004). Choline at 4 × and 6 × RA decreased serum BUN (P = 0.006). Fed or fasted respiratory quotient and energy expenditure did not differ among dietary choline doses (P > 0.05). These results suggest that dietary choline supplementation at 6 × RA may increase hepatic fat mobilization through increased lipoprotein transport and beneficially support hepatic health in overweight cats. Future studies that combine these results with existing knowledge of feline weight loss and hepatic lipidosis are warranted.

Acute pancreatitis induces cytokine production in endotoxin-resistant mice

OBJECTIVE

The purpose of this study was to determine whether pathologic progression and cytokine responses in acute pancreatitis (AP) are altered in the absence of endotoxemia.

SUMMARY BACKGROUND DATA

Previous studies have demonstrated that AP is characterized by rapid production and release of inflammatory cytokines, which play a major role in the local pancreatic and systemic complications of this disease. Infection and endotoxemia have been implicated as a major source of morbidity and death in AP and as possible stimuli for the overwhelming cytokine response seen in this disease.

METHODS

AP was induced by a choline-deficient and ethionine-supplemented diet for 4 days in normal C57BL/6J mice (controls, n = 23) and in CD14 knockout mice (CD14KO, n = 23), which cannot produce circulating cytokines in response to endotoxin. Control and endotoxin-resistant mice were killed at time 0, then at 24, 48, 72, and 96 hours after the start of the diet. At each time point serum was collected for amylase, glucose, and cytokine measurements (tumor necrosis factor-alpha [TNFalpha] and interleukin-1beta [IL1beta]), and the pancreas was removed for histologic examination. TNFalpha was measured with a bioassay using WEHI-2F cells and IL1beta with a bioassay using D10.G4.1 cells.

RESULTS

CD14KO mice developed biochemical manifestations of AP with alterations in amylase levels, hypoglycemia, weight loss, and histologic changes of pancreatitis similar to the pattern seen in control mice. TNFalpha and IL1beta production had similar kinetics in both groups, with significant peak TNFalpha serum levels at 72 hours and a progressive rise of IL1beta levels throughout the study period. Histologic changes appeared earlier and were more pronounced in the control versus the CD14KO mice. However, the mortality rate was identical (20% at 96 hours) for both groups.

CONCLUSIONS

These results demonstrate that the progression of AP, the cytokine response associated with the disease, and early death are independent of endotoxin action. These findings, which suggest that an uncharacterized stimulus is responsible for triggering the cytokine cascade in this disease, may have significant implications for the management of patients with AP.

New insight into the biochemical pathology of liver in choline deficiency

A diet deficient in choline can cause liver cancer in rats. The previous work since 1932 emphasized the fat-removing ability of choline from the liver. There are other dietary factors, including methionine, which, like choline, can remove fat from the liver. These factors were termed as lipotropes. Since then, choline deficiency and lipotrope deficiency are used synonoumously. Recent work since 1980 has clearly demonstrated that choline deficiency (CD) and lipotrope deficiency (LD) are not the same. Generation of free radicals, DNA alterations, liver cell death, and liver cancer that occur due to CD are not generated by LD. Generation of free radicals due to CD diet and some of the agents that counteract free radical action also prevent CD effects except for lipid accumulation in the liver. Despite the recent observations on the role of phospholipase A2 (PLA2) as the protector of the membranes, it has been found that by preventing the rise of PLA2 in the liver, cell death can be prevented. These new findings give choline a distinct role in liver cell death and cancer rather than the role of lipotrope. A new hypothesis linking dietary choline deficiency and liver cancer has been discussed.

Effects of a choline-deficient diet and a hypolipidemic agent on single glutathione S-transferase placental form-positive hepatocytes in rat liver

Using the placental form of glutathione S-transferase (GST-P) as a marker of carcinogen-initiated hepatocytes, we investigated how a choline-deficient (CD) diet and BR931, a carcinogenic hypolipidemic agent, modify populations of single GST-P-positive hepatocytes. The liver of male Fischer rats (6-7 weeks old) fed a CS or basal diet contained mostly single or double GST-P-positive hepatocytes. Feeding a CD diet for 2-4 weeks led to increases in the number of aggregates of two and three GST-P-positive hepatocytes. By 8-12 weeks, there was an emergence of discrete foci of GST-P-positive hepatocytes consisting of more than 20 hepatocytes. Feeding a BR931 diet for 4-8 weeks resulted in no significant change in the number of single GST-P-positive hepatocytes in the liver as compared to feeding a basal diet. It is suggested that single GST-P-positive hepatocytes in the liver of relatively young rats maintained on a commercial diet may represent endogenously initiated cells. A CD diet promotes endogenously initiated cells to form larger aggregates or foci of GST-P-positive cells.

The methionine and choline status of rat diets and their effects on nutrition and myocardial lesions

This study evaluated for rats the nutritional adequacy of casein-based diets routinely used to test the cardiopathogenicity of vegetable oils. Diets were formulated containing 20% by weight casein, 20% soybean oil and graded levels of choline with and without methionine and were fed to male Sprague-Dawley rats for 16 weeks. Rats fed methionine-supplemented diets had improved growth and food consumption, increased liver lipids mainly in the form of triglycerides and normal amino acid metabolism. On the other hand, choline supplementation reduced liver lipids but had no effect on growth and feed consumption. The results would indicate that diets including 20% casein and 20% oil require methionine supplementation to assure the nutritional adequacy of this high caloric diet. However, in this study there was no evidence to indicate that choline or methionine supplementation affected the heart lesion incidence in male rats. It was therefore concluded that the amount and type of fat in the diet, not the choline and methionine status of the diet, is related to heart lesions in male rats.