High-fat diet-induced obesity Rat model: a comparison between Wistar and Sprague-Dawley Rat

Abstract

In the past decades, obesity and associated metabolic complications have reached epidemic proportions. For the study of these pathologies, a number of animal models have been developed. However, a direct comparison between Wistar and Sprague-Dawley (SD) Rat as models of high-fat (HF) diet-induced obesity has not been adequately evaluated so far. Wistar and SD rats were assigned for 2 experimental groups for 17 weeks: standard (St) and high-fat (HF) diet groups. To assess some of the features of the metabolic syndrome, oral glucose tolerance tests, systolic blood pressure measurements and blood biochemical analysis were performed throughout the study. The gut microbiota composition of the animals of each group was evaluated at the end of the study by real-time PCR. HF diet increased weight gain, body fat mass, mesenteric adipocyte's size, adiponectin and leptin plasma levels and decreased oral glucose tolerance in both Wistar and SD rats. However, the majority of these effects were more pronounced or earlier detected in Wistar rats. The gut microbiota of SD rats was less abundant in Bacteroides and Prevotella but richer in Bifidobacterium and Lactobacillus comparatively to the gut microbiota of Wistar rats. Nevertheless, the modulation of the gut microbiota by HF diet was similar in both strains, except for Clostridium leptum that was only reduced in Wistar rats fed with HF diet. In conclusion, both Wistar and SD Rat can be used as models of HF diet-induced obesity although the metabolic effects caused by HF diet seemed to be more pronounced in Wistar Rat. Differences in the gut microbial ecology may account for the worsened metabolic scenario observed in Wistar Rat.

Keywords: animal models; diet-induced obesity; high-fat diet; metabolic syndrome; microbiota; obesity.

Figure 1.

Energy ingestion (A) and body weight (B) of Wistar and Sprague-Dawley (SD) rats fed either with standard (St) or high-fat (HF) diet along the 17 weeks of the study. Data are presented as mean ± SEM (n = 6 rats per group).^£P < 0.05 between St and HF diet groups of both strains and^δ P < 0.05 between St and HF diet groups of Wistar rats.

Figure 2.

Glycaemic response during oral glucose tolerance test (A), total area under the curve (AUC) (B), fasting insulin plasma levels (C) and homeostasis model assessment (HOMA) (D) of Wistar and Sprague-Dawley (SD) rats after 9 weeks of feeding either with standard (St) or high-fat (HF) diet. HOMA was calculated using the formula: fasting glucose (mg/dl) × fasting insulin (ng/ml)/405. Data are presented as mean ± SEM (n = 5–6 rats per group). *P < 0.05 vs respective St diet group and ^†P < 0.05 between HF diet groups.

Figure 3.

Glycaemic response during oral glucose tolerance test (A) and total area under the curve (AUC) (B) of Wistar and Sprague-Dawley (SD) rats after 16 weeks of feeding either with standard (St) or high-fat (HF) diet. Data are presented as mean ± SEM (n = 6 rats per group).

Figure 4.

Systolic blood pressure (A) and serum endotoxin levels (B) of Wistar and Sprague-Dawley (SD) rats fed either with standard (St) or high-fat (HF) diet during 17 weeks. SBP measurements were recorded at 15^th week of the study. Data are presented as mean ± SEM (n = 5–6 rats per group).

Figure 5.

Adiponectin (A) and leptin plasma levels (B) of Wistar and Sprague-Dawley (SD) rats fed either with standard (St) or high-fat (HF) diet during 17 weeks. Data are presented as mean ± SEM (n = 6 rats per group). *P < 0.05 vs respective St diet group, ^‡P < 0.05 between St diet groups and ^†P < 0.05 between HF diet groups.

Figure 6.

Mesenteric adipocyte's area (A) of Wistar and Sprague-Dawley (SD) rats fed either with standard (St) or high-fat (HF) diet during 17 weeks. Data are presented as mean ± SEM (n = 6 rats per group). (B) Representative images of hematoxylin and eosin stained-adipose tissue sections for each experimental group.

Figure 7.

Correlations between gut microbiota and host metabolic parameters. Data of all experimental groups were gathered and analyzed by SPSS software (20.0 version) using 2-tailed Pearson's correlation test. The scores of Pearson's correlation were figured by PermutMatrix software (Version 1.9.3 EN) using heatmap plots. As shown by the colors scale, green color indicates a negative correlation while red color indicates a positive correlation. The symbol (*) indicates a statistical significant correlation (P < 0.05).