BACKGROUND: Leucine is one of the subgroups of amino acids, which play an important role in the anabolism of muscles, adipose tissue, and the liver by stimulating insulin secretion.OBJECTIVES: Effects of different levels of leucine were investigated on carcass yield, characteristics, and quality, and expression of insulin-like growth factor (IGF-1) and insulin genes in male broilers.METHODS: Five levels of L-leucine (100, 110, 120, 130, and 140 % of Ross strain requirements) were tested with 250 male one-day-old chicks in a completely randomized design with five treatments and five replicates (containing 10 chicks each). On day 42 of their age, the blood samples of two birds from each replicate (10 birds per treatment) were taken to determine serum IGF-1 gene expression. Subsequently, these birds were slaughtered for analysis of carcass characteristics and quality, and collecting the samples of liver and breast for expression of IGF-1 and insulin genes.RESULTS: Body weight increased by consumption of 140 % of leucine as compared to 100 %. Reduction in feed conversion ratio was observed by feeding 140 % of leucine level. The IGF-1 gene expression of breast and liver increased by 110 % of leucine level. Moreover, feeding 110 % of leucine level caused a higher expression of insulin gene in breast and liver. Consumption of 130 % of leucine improved the meat protein, fat, and ash contents. Furthermore, consumption of 110 % of leucine increased the serum IGF-1 concentration.CONCLUSIONS: Consumption of leucine in broiler diets was found to increase the expression of IGF-1 and insulin genes and consequently, improve the performance and carcass quality. It also decreased the abdominal fat in broiler chickens.

OBJECTIVE To develop a technique for isolation and culture of canine insulinoma cells and assess expression of cellular hexokinases (glucokinase and hexokinase I) and expression and secretion of insulin from these cells in vitro. SAMPLE Pancreatic insulinomas and normal pancreatic tissue from 4 and 3 dogs, respectively. PROCEDURES Tissues were collected by surgical excision or at necropsy. Insulinoma cells from 2 dogs were cultured for up to 10 weeks with standard techniques; insulin synthesis in vitro was confirmed by immunohistochemical analysis of freshly prepared slides of cultured cells, and insulin secretion was assessed by measurement of insulin concentrations in culture medium with an ultrasensitive mouse insulin ELISA. Expression of cellular hexokinases in insulinomas and adjacent normal (nontumor) pancreatic tissue from the same dog (n = 3) was examined by quantitative reverse transcriptase PCR assay. RESULTS Insulinoma cells survived for up to 10 weeks but did not proliferate in culture. Insulin was detected in isolated cells and secreted into culture medium for up to 10 weeks. Both cellular hexokinases were expressed; glucokinase appeared to be overexpressed in insulinomas, compared with normal pancreatic tissue from the same dogs. CONCLUSIONS AND CLINICAL RELEVANCE Canine insulinomas expressed hexokinases responsible for glucose responsiveness. Insulinoma cells were successfully maintained in short-term culture; cultured cells remained functional for 10 weeks as evidenced by cellular insulin content and had detectable secretion of insulin into the culture medium for ≥ 5 weeks. Apparent glucokinase overexpression by insulinomas suggested a possible mechanism underlying excessive insulin release by these tumors.

From 50 to 60% of companion animals in the United States are overweight or obese and this obesity rate is rising. As obesity is associated with a number of health problems, an agent that can help weight loss in pets and assist in clinically managing obesity through veterinary prescription foods and medication would be beneficial. Many studies have shown that celastrol, a phytochemical compound found in Celastrus orbiculatus extract (COE), has anti-obesity and anti-inflammatory effects, although these effects have not yet been determined in canine or canine-derived cells. The objective of this study was to investigate the effects of celastrol on the adipogenic differentiation and lipolysis of canine adipocytes. Primary preadipocytes were isolated from the gluteal region of a beagle dog and the primary adipocytes were differentiated into mature adipocytes by adipocyte differentiation media containing isobutylmethylxanthine, dexamethasone, and insulin. In a water-soluble tetrazolium (WST) assay, the cell viability of mature adipocytes was decreased after treatment with COE (0, 0.93, 2.32, and 4.64 nM celastrol) in a concentration-dependent manner, although preadipocytes were not affected. Oil Red O (ORO) staining revealed that COE inhibited the differentiation into mature adipocytes and lipid accumulation in adipocytes. In addition, treatment with COE significantly reduced triglyceride content and increased lipolytic activities by 1.5-fold in canine adipocytes. Overall, it was concluded that COE may enhance anti-obesity activity in canine adipocytes by inhibiting lipid accumulation and increasing lipolytic activity.