ABSTRACT. Plasma lipoprotein cholesterol in 64 clinically healthy Shetland sheepdogs was evaluated to assess whether the breed is more susceptible to hypercholesterolemia. The incidence of hypercholesterolemia was clearly higher in Shetland sheepdogs and mean plasma cholesterol level was significantly higher in Shetland sheepdogs than in control dogs. Blood biochemical examinations did not evidence the abnormalities, which imply the causative disorders, and thyroid hormone levels were not significantly different from the controls. These results suggest that the cholesterolemia is a primary disorder. Cholesterol fractionation by agarose gel electrophoresis and ultracentrifugation revealed that accumulation of α 2 -migrating lipoproteins was the common characteristic of dogs showing cholesterol level over 250 mg/dl in the breed. Increase in preβ~β-lipoproteins was also found in Shetland sheepdogs with marked hypercholesterolemia over 500 mg/dl. Therefore, Shetland sheepdogs may include more dogs with primary disorders in lipoprotein metabolism, which cause hypercholesterolemia, at least in Japan. KEY WORDS: cholesterol, high density lipoprotein, low density lipoprotein, Shetland sheepdog.

The effects of several factors related to lipids on bovine adipocyte differentiation were investigated in primary culture. Adipocyte differentiation was assessed by development of glycerol-3-phosphate dehydrogenase (GPDH) activity and morphological observation. Addition of triglyceride mixture (Intralipid), caprylic acid and very low-, low- and high-density lipoproteins (VLDL, LDL and HDL) stimulated bovine preadipocyte differentiation in serum-free condition. Especially, VLDL strongly increased both cell protein contents and GPDH activity, suggesting that it stimulated both proliferation and differentiation of bovine preadipocytes. Under Intralipid-induced condition, differentiation of preadipocytes from subcutaneous adipose tissues was more evident than those from omental adipose tissues. However, such depot difference was not observed in medium supplemented with indomethacin, which is a peroxisome proliferator-activated receptor (PPAR) gamma agonist. This suggests that the differentiation capacity of bovine preadipocytes was different between depots and such difference is dependent on the ability to utilize lipids as endogenous PPARgamma ligands. Therefore, lipid metabolites have the stimulatory effects on bovine adipocyte differentiation in vitro, and lipoproteins, especially VLDL, may play an important role in development of bovine adipose tissues in vivo.

Canine red cells have a high affinity Na؉ /K ؉ -dependent glutamate transporter. We herein demonstrate that this transport is mediated by the canine homologue of glutamate/aspartate transporter (GLAST), one of the glutamate transporter subtypes abundant in the central nervous system. We also demonstrate that GLAST is the most ubiquitous glutamate transporter among the transporter subtypes that have been cloned to date. The GLAST protein content was extremely reduced in variant red cells, low glutamate transport (LGlut) red cells characterized by an inherited remarkable decrease in glutamate transport activity. All LGluT dogs carried a missense mutation of Gly 492 to Ser (G492S) in either the heterozygous or homozygous state. The GLAST protein with G492S mutation was fully functional in glutamate transport in Xenopus oocytes. However, G492S GLAST exhibited a marked decrease in activity after the addition of cycloheximide, while the wild type showed no significant change, indicating that G492S GLAST was unstable compared with the wild-type transporter. Moreover, LGluT dogs, but not normal dogs, heterozygous for the G492S mutation showed a selective decrease in the accumulation of GLAST mRNA from the normal allele. Based on these findings, we conclude that a complicated heterologous combination of G492S mutation and some transcriptional defect contributes to the pathogenesis of the LGluT red cell phenotype.

ABSTRACT. A culture condition supporting adipocyte differentiation of stromal-vascular (S-V) cells isolated from canine adipose tissues was established. Morphological observation and determination of glycerol-3-phosphate dehydrogenase (GPDH) activity were used as the criteria for adipocyte differentiation. After reaching confluence, the cells were able to undergo terminal adipocyte differentiation by treatment with 100 µM indomethacin, 10 µg/ml insulin and 0.5 mM 1-methyl-3-isobutylxanthine (MIX) in medium supplemented with 5% fetal calf serum (FCS). In the absence of either indomethacin or insulin, the S-V cells did not undergo adipose conversion and GPDH activity was not increased, indicating that both indomethacin and insulin play essential roles in this culture system. The S-V cells from inguinal adipose tissues exhibited the greatest increase in GPDH activity among the four depots (inguinal > abdominal-subcutaneous > perirenal > omental), demonstrating that adipocyte differentiation was also intensely dependent on anatomic sites from which the S-V cells were derived. Interestingly, dimethylsulfoxide (DMSO) was found to accelerate adipocyte differentiation in combination with indomethacin and insulin. Under this condition, up to 90% of the cells displayed adipocyte phenotypes and the GPDH activity reached 1288 ± 441 mU/mg protein. This culture system may be useful for investigating other adipogenic factors as well as anti-adipogenic factors involved in the regulation of canine adipose tissue development. KEY WORDS: adipocyte differentiation, canine, cell culture, dimethylsulfoxide, indomethacin.J. Vet. Med. Sci. 63(1): 17-23, 2001 In 1974 Green and Kehinde reported that sublines of 3T3 cells underwent adipose differentiation in vitro [19], and since then many other adipogenic cell lines have been established [7,30,34,36]. The development of culture conditions supporting the proliferation and differentiation of adipogenic cell lines or stromal-vascular (S-V) cells from adipose tissues has provided interesting models to study the nature and mechanisms of factors which control the process of adipocyte differentiation. In primary culture, cells carry physiological host factors from the donor animal to the culture [4]. This fact might be an advantage in the study of the physiological regulatory mechanisms when compared with other adipose precursor cells in established cell lines [40]. In recent years, primary culture systems have been established for rat, mouse, sheep, pig, cattle and human preadipocyte differentiation [3,4,6,10,23,37]. However, such culture conditions developed for one species cannot be simply applied to other species, because the specific properties of preadipocytes are different among animal species. In addition, obesity due to excessive formation of adipose tissue is the most common nutritionally related-health problem for dogs and cats [15], and 25 to 44% of pet dogs are obese [16,29]. Therefore, in order to gain a better understanding of factors involved in the regulation of canine adipo...

Pathological and biochemical studies were performed on a 9-month-old boxer dog with progressive neurological abnormality. Histological examination revealed marked neuronal storage throughout the central nervous system and histiocytic storage in the reticuloendothelial system. Ultrastructurally, the neuronal storage consisted of accumulation of concentric membranous inclusions and clusters of dense bodies. The biochemically unesterified cholesterol content was high in the liver and spleen. The brain showed increased levels of lactosylceramide and two gangliosides, GM3 and GM2. These findings indicate that this dog was affected with a heterogeneous lipid storage disease similar to the human Niemann-Pick type C disease.