Nuciferine prevents hepatic steatosis and injury induced by a high-fat diet in hamsters

Abstract

Background: Nuciferine is a major active aporphine alkaloid from the leaves of N. nucifera Gaertn that possesses anti-hyperlipidemia, anti-hypotensive, anti-arrhythmic, and insulin secretagogue activities. However, it is currently unknown whether nuciferine can benefit hepatic lipid metabolism.

Methodology/principal findings: In the current study, male golden hamsters were randomly divided into four groups fed a normal diet, a high-fat diet (HFD), or a HFD supplemented with nuciferine (10 and 15 mg/kg·BW/day). After 8 weeks of intervention, HFD-induced increases in liver and visceral adipose tissue weight, dyslipidemia, liver steatosis, and mild necroinflammation in hamsters were analyzed. Nuciferine supplementation protected against HFD-induced changes, alleviated necroinflammation, and reversed serum markers of metabolic syndrome in hamsters fed a HFD. RT-PCR and western blot analyses revealed that hamsters fed a HFD had up-regulated levels of genes related to lipogenesis, increased free fatty acid infiltration, and down-regulated genes involved in lipolysis and very low density lipoprotein secretion. In addition, gene expression of cytochrome P4502E1 and tumor necrosis factor-α were also increased in the HFD group. Nuciferine supplementation clearly suppressed HFD-induced alterations in the expression of genes involved in lipid metabolism.

Conclusions/significance: Nuciferine supplementation ameliorated HFD-induced dyslipidemia as well as liver steatosis and injury. The beneficial effects of nuciferine were associated with altered expression of hepatic genes involved in lipid metabolism.

Figure 1. Effects of nuciferine on serum lipid profile and free fatty acid.

(A) Serum triglyceride, (B) serum total cholesterol, (C) serum low-density lipoprotein cholesterol, (D) serum high-density lipoprotein cholesterol, and (E) serum free fatty acid. Values are means±SD, n = 10 hamsters in each group. ND: normal diet group, HFD: high-fat diet group, HFNL: low dosage nuciferine group (HFD+10 mg/kg·BW/day), HFNH: high dosage nuciferine group (HFD+15 mg/kg·BW/day). a, b, c: Means in the same row with different online letters differ significantly, p<0.05.

Figure 2. Effects of nuciferine on hepatic lipids and serum activities of ALT.

(A) hepatic triglyceride, (B) hepatic cholesterol, (C) hepatic free fatty acid, (D) serum activity of ALT. Values are means±SD, n = 10 hamsters in each group. ND: normal diet group, HFD: high-fat diet group, HFNL: low dosage nuciferine group (HFD+10 mg/kg·BW/day), HFNH: high dosage nuciferine group (HFD+15 mg/kg·BW/day). a, b, c, d: Means in the same row with different online letters differ significantly, p<0.05.

Figure 3. Effects of nuciferine on liver histology.

(A) Liver sections from hamsters fed the normal diet showed normal liver histology. (B) In HFD fed hamsters, numerous macrovesicular fat droplets (arrow head) and mild necroinflammatory foci (arrows) were present. (C) and (D) Treatment with nuciferine (10 and 15 mg/kg·BW/day) for 8 weeks resulted in prevention of hepatic fatty deposition in hepatocytes and infiltration of the inflammatory cells in the hepatic parenchyma. The tissues were surgically excised and subjected to histological study by staining with hematoxylin and eosin. All the magnification is 200×.

Figure 4. Effecs of nuciferine on hepatic protein levels of PPAR-α, CD36, FAS and SREBP-1c in high-fat fed hamsters.

(A) Representative immunoblot showing the analysis of each protein. (B) Data graphed from image densitometric analysis of blots obtained from tissues of 10 separate animals (n = 10). ND: normal diet group, HFD: HFD group, HFNL: low dosage nuciferine group (HFD+10 mg/kg·BW/day), HFNH: high dosage nuciferine group (HFD+15 mg/kg·BW/day). a, b, c, d: Means in the same row with different online letters differ significantly, p<0.05.