Rat pancreatectomy combined with isoprenaline or uninephrectomy as models of diabetic cardiomyopathy or nephropathy.

Cardiovascular and renal complications are the predominant causes of morbidity and mortality amongst patients with diabetes. Development of novel treatments have been hampered by the lack of available animal models recapitulating the human disease. We hypothesized that experimental diabetes in rats combined with a cardiac or renal stressor, would mimic diabetic cardiomyopathy and nephropathy, respectively. Diabetes was surgically induced in male Sprague Dawley rats by 90% pancreatectomy (Px). Isoprenaline (Iso, 1 mg/kg, sc., 10 days) was administered 5 weeks after Px with the aim of inducing cardiomyopathy, and cardiac function and remodeling was assessed by echocardiography 10 weeks after surgery. Left ventricular (LV) fibrosis was quantified by Picro Sirius Red and gene expression analysis. Nephropathy was induced by Px combined with uninephrectomy (Px-UNx). Kidney function was assessed by measurement of glomerular filtration rate (GFR) and urine albumin excretion, and kidney injury was evaluated by histopathology and gene expression analysis. Px resulted in stable hyperglycemia, hypoinsulinemia, decreased C-peptide, and increased glycated hemoglobin (HbA1c) compared with sham-operated controls. Moreover, Px increased heart and LV weights and dimensions and caused a shift from α-myosin heavy chain (MHC) to ß-MHC gene expression. Isoprenaline treatment, but not Px, decreased ejection fraction and induced LV fibrosis. There was no apparent interaction between Px and Iso treatment. The superimposition of Px and UNx increased GFR, indicating hyperfiltration. Compared with sham-operated controls, Px-UNx induced albuminuria and increased urine markers of kidney injury, including neutrophil gelatinase-associated lipocalin (NGAL) and podocalyxin, concomitant with upregulated renal gene expression of NGAL and kidney injury molecule 1 (KIM-1). Whereas Px and isoprenaline separately produced clinical endpoints related to diabetic cardiomyopathy, the combination of the two did not accentuate disease development. Conversely, Px in combination with UNx resulted in several clinical hallmarks of diabetic nephropathy indicative of early disease development.

Impact of sex on diabetic nephropathy and the renal transcriptome in UNx db/db C57BLKS mice.

Diabetic nephropathy (DN) is associated with albuminuria and loss of kidney function and is the leading cause of end-stage renal disease. Despite evidence of sex-associated differences in the progression of DN in human patients, male mice are predominantly being used in preclinical DN research and drug development. Here, we compared renal changes in male and female uninephrectomized (UNx) db/db C57BLKS mice using immunohistochemistry and RNA sequencing. Male and female UNx db/db mice showed similar progression of type 2 diabetes, as assessed by obesity, hyperglycemia, and HbA1c. Progression of DN was also similar between sexes as assessed by kidney and glomerular hypertrophy as well as urine albumin-to-creatinine ratio being increased in UNx db/db compared with control mice. In contrast, kidney collagen III and glomerular collagen IV were increased only in female UNx db/db as compared with respective control mice but showed a similar tendency in male UNx db/db mice. Comparison of renal cortex transcriptomes by RNA sequencing revealed 66 genes differentially expressed (p < .01) in male versus female UNx db/db mice, of which 9 genes were located on the sex chromosomes. In conclusion, male and female UNx db/db mice developed similar hallmarks of DN pathology, suggesting no or weak sex differences in the functional and structural changes during DN progression.

Towards a standard diet-induced and biopsy-confirmed mouse model of non-alcoholic steatohepatitis: Impact of dietary fat source.

BACKGROUND: The trans-fat containing AMLN (amylin liver non-alcoholic steatohepatitis, NASH) diet has been extensively validated in C57BL/6J mice with or without the Lepob/Lepob (ob/ob) mutation in the leptin gene for reliably inducing metabolic and liver histopathological changes recapitulating hallmarks of NASH. Due to a recent ban on trans-fats as food additive, there is a marked need for developing a new diet capable of promoting a compatible level of disease in ob/ob and C57BL/6J mice. AIM: To develop a biopsy-confirmed mouse model of NASH based on an obesogenic diet with trans-fat substituted by saturated fat. METHODS: Male ob/ob mice were fed AMLN diet or a modified AMLN diet with trans-fat (Primex shortening) substituted by equivalent amounts of palm oil [Gubra amylin NASH, (GAN) diet] for 8, 12 and 16 wk. C57BL/6J mice were fed the same diets for 28 wk. AMLN and GAN diets had similar caloric content (40% fat kcal), fructose (22%) and cholesterol (2%) level. RESULTS: The GAN diet was more obesogenic compared to the AMLN diet and impaired glucose tolerance. Biopsy-confirmed steatosis, lobular inflammation, hepatocyte ballooning, fibrotic liver lesions and hepatic transcriptome changes were similar in ob/ob mice fed the GAN or AMLN diet. C57BL/6J mice developed a mild to moderate fibrotic NASH phenotype when fed the same diets. CONCLUSION: Substitution of Primex with palm oil promotes a similar phenotype of biopsy-confirmed NASH in ob/ob and C57BL/6J mice, making GAN diet-induced obese mouse models suitable for characterizing novel NASH treatments.