Analysis of the Effect of the TRPC4/TRPC5 Blocker, ML204, in Sucrose-Induced Metabolic Imbalance

Abstract

Sugar-induced metabolic imbalances are a major health problem since an excessive consumption of saccharides has been linked to greater obesity rates at a global level. Sucrose, a disaccharide composed of 50% glucose and 50% fructose, is commonly used in the food industry and found in a range of fast, restaurant, and processed foods. Herein, we investigated the effects of a TRPC4/TRPC5 blocker, ML204, in the metabolic imbalances triggered by early exposure to sucrose-enriched diet in mice. TRPC4 and TRPC5 belong to the family of non-selective Ca⁺² channels known as transient receptor potential channels. High-sucrose (HS)-fed animals with hyperglycaemia and dyslipidaemia, were accompanied by increased body mass index. mesenteric adipose tissue accumulation with larger diameter cells and hepatic steatosis in comparison to those fed normal diet. HS mice also exhibited enhanced adipose, liver, and pancreas TNFα and VEGF levels. ML204 exacerbated hyperglycaemia, dyslipidaemia, fat tissue deposition, hepatic steatosis, and adipose tissue and liver TNFα in HS-fed mice. Normal mice treated with the blocker had greater hepatic steatosis and adipose tissue cell numbers/diameter than those receiving vehicle, but showed no significant changes in tissue inflammation, glucose, and lipid levels. The results indicate that TRPC4/TRPC5 protect against the metabolic imbalances caused by HS ingestion.

Keywords: TRPC4 and TRPC5 channels; fat deposition; hepatic steatosis; high sucrose intake; metabolic changes.

Figure 1

Effects of high-sucrose (HS) diet on body weight, body mass (BMI), and Lee indexes, and glycaemia. Animals received either HS or standard diet for 20 weeks (n = 6/group). Body weight gain (A) and BMI (B) were registered once a week. Lee index (C) was measured once a week from the 18th week, and blood glucose levels (D) were recorded at every 5 weeks. Glucose was measured in non-fasted animals. * p < 0.05, differs from the standard diet group.

Figure 2

Repeated ML204 treatment increases blood glucose levels and impairs glucose tolerance. Animals received either a high-sucrose or standard diet for 20 weeks (n = 8/group). Body weight gain (A) and body mass index (BMI; (B)) were registered once a week. Lee index (C) was measured once a week from the 18th week. Blood glucose levels (D) were recorded at every 5 weeks and a glucose tolerance test (E) was performed at the 20th week. Glucose and glucose tolerance were measured in non-fasted and fasted animals, respectively. ML204 (2 mg/kg) or vehicle (3% dimethyl sulfoxide (DMSO) in phosphate-buffered saline (PBS)) was administered subcutaneously, once a day, for 7 days starting at the beginning of the 19th week. * p < 0.05, differs from the standard diet group; ^# p < 0.05, differs from the high-sucrose diet control group.

Figure 3

Repeated ML204 treatment causes hypertriglyceridaemia and exacerbates hypercholesterolemia in animals fed a high-sucrose (HS) diet. Animals received either HS or standard diet for 20 weeks (n = 8/group). Triglyceride (A) and total cholesterol (B) levels were measured at the end of the 20th week. ML204 (2 mg/kg) or vehicle (3% DMSO in PBS) was administered subcutaneously, once a day, for 7 days starting at the beginning of the 19th week. * p < 0.05, differs from the standard diet group; ^# p < 0.05, differs from the high-sucrose diet control group.

Figure 4

Repeated ML204 treatment enhances inflammation in the adipose and liver tissues of animals fed a high-sucrose (HS) diet. Animals received either HS or standard diet for 20 weeks (n = 8/group). TNFα was measured in (A) adipose tissue, (C) liver, and (E) pancreas. Adipose (B), liver (D), and pancreas (F) VEGF tissue levels. Samples were collected at the end of the 20th week. ML204 (2 mg/kg) or vehicle (3% DMSO in PBS) was administered subcutaneously, once a day, for 7 days starting at the beginning of the 19th week. * p < 0.05, differs from the standard diet group; ^# p < 0.05, differs from the high-sucrose diet control group.

Figure 5

Repeated ML204 treatment causes fat accumulation in animals fed high-sucrose (HS) diet and the size of adipocytes in those receiving standard diet. (A) Representative H&E histology sections of adipose tissue (20 and 50 µm areas) from animals fed either HS or standard diet for 20 weeks (n = 8/group). Mesenteric fat/body weight ratios (B), adipocyte area (C), and size (D) measured at the end of the 20th week. ML204 (2 mg/kg) or vehicle (3% DMSO in PBS) was administered subcutaneously, once a day, for 7 days starting at the beginning of the 19th week. Samples were stained by haematoxylin and eosin (H&E). * p < 0.05, differs from the standard diet group; ^# p < 0.05, differs from the high-sucrose diet control group.

Figure 6

Repeated ML204 treatment increases non-alcoholic fatty liver disease (NALFD) activity score (NAS) in high-sucrose (HS)-fed mice. (A) Representative H&E histology sections of liver (50 and 100 µm areas) from animals fed either HS or standard diet for 20 weeks (n = 8/group). NAS (B) and steatosis score (C) were measured at the end of the 20th week. ML204 (2 mg/kg) or vehicle (3% DMSO in PBS) was administered subcutaneously, once a day, for 7 days starting at the beginning of the 19th week. NAS was determined by the summation of hepatic steatosis (red arrows), ballooning (orange arrows), and inflammatory cell influx (dark green arrows) scores. Samples were stained by haematoxylin and eosin (H&E). * p < 0.05, differs from the standard diet group; ^# p < 0.05, differs from the high-sucrose diet control group.