Serum metabolites, ghrelin and leptin are modified by age and/or diet in weanling kittens fed either a high- or moderate-protein diet.

The objective of this study was to evaluate the effects of in utero and postnatal exposure of a high-protein (HP; n=9) or moderate-protein (MP; n=16) diet on growth, and serum metabolite, ghrelin and leptin concentrations during the first 4 months of life in kittens. It was hypothesized that blood indices would be modified due to diet. Blood samples were collected from kittens at 4, 8, 12 and 16 weeks of age. Kittens were weaned at 8 weeks of age onto the same diet as the dam. Body weight was measured weekly from birth and daily food intake for each litter was recorded post-weaning. Serum concentrations of urea nitrogen, total protein and triglycerides were greater (P<0.05) in kittens fed the HP diet. Serum cholesterol concentrations were greater (P <0.05) in MP-fed kittens at 4 weeks of age. Moderate-protein fed kittens tended to have greater (P < 0.10) serum ghrelin concentrations. Leptin concentrations were not affected by diet, but changed over time (P<0.05). Our data indicate that diet and age of kittens affect circulating concentrations of peptides important in appetite regulation. Further research testing the effects of in utero and early postnatal nutrient exposure on feline obesity risk in adulthood is needed.

Adipose tissue gene expression profiles of healthy young adult and geriatric dogs.

Obesity is a major problem in today's dog population, with aged animals having an increased susceptibility to obesity-related comorbidities. A molecular approach to studying adipose tissue may enhance our understanding of its role in energy homeostasis and the disease process. Thus, the objective of this study was to use canine microarrays to compare gene expression profiles of adipose tissue from geriatric and young adult dogs. Adipose tissue samples were collected from six geriatric (12 year-old) and six young adult (one-year-old) female beagles after being fed one of two diets (animal protein-based vs. plant protein-based) for 12 months. RNA samples were hybridised to canine microarrays. Statistical analyses indicated that age had the greatest impact on gene expression, with 65 differentially expressed gene transcripts in geriatric dogs. Diet had a minor impact on gene expression, altering the expression of only 19 gene transcripts. In general, adipose tissue of geriatric dogs had increased expression of genes associated with cell cycle and growth, cell development and structure, cellular trafficking and protein processing, immune function, metabolism, and transcription and translation, as compared with that of young adults. Overall, our mRNA data suggest either an increased population of macrophages or increased inflammatory nature of adipocytes in adipose tissue of aged dogs.

Short-chain fructooligosaccharides influence insulin sensitivity and gene expression of fat tissue in obese dogs.

Dietary fibers may modulate insulin resistance and glucose homeostasis in dogs. Their efficacy is, however, dependent on their origin, physical properties, and fermentability in the large bowel. Eight healthy Beagle dogs were fed a commercial diet at twice their maintenance requirements until they became obese. They were then maintained in the obese state and used in a cross-over design study to evaluate the effects of short-chain fructooligosaccharide (scFOS) supplementation (1% wt:wt dry matter in the diet). The euglycemic hyperinsulinemic clamp technique was performed before and after fattening and at the end of each 6-wk cross-over period. Fat tissue biopsies were taken in food-deprived and postprandial phases to measure mRNA abundance of genes involved with fatty acid, glucose metabolism, or inflammation. Insulin resistance appeared progressively with fattening and the rate of glucose infusion during euglycemic clamp was lower (P < 0.05) at the end of the fattening period (7.39 mg.kg(-1).min(-1)) than at baseline (21.21 mg.kg(-1).min(-1)). In stable obese dogs, scFOS increased (P < 0.05) the rate of glucose infusion compared with control (7.77 vs. 4.72 mg.kg(-1).min(-1)). Plasma insulin and triglyceride concentrations were greater in obese than in lean dogs but were not altered by scFOS. Whereas mRNA was not affected in food-deprived dogs, scFOS increased uncoupling protein 2 (P = 0.05) and tended to increase carnitine palmitoyl transferase 1 adipose mRNA levels during the postprandial period (P = 0.09). Adding 1% scFOS to the diet of obese dogs decreases insulin resistance and appears to modulate the transcription of genes involved in fatty acid or glucose metabolism.