Fig 1.
High-fat diet induced insulin resistance in tga20 mice.
(A) Left: Body weight of tga20 mice fed with either high-fat diet (HFD) or normal diet (ND). After 4 weeks, HFD-fed mice gained significantly more body weight than ND-fed mice after 4 weeks. (n = 6; ***: p<0.001). Right: appearance of mice fed with ND or HFD for 4 weeks. (B) Fasting glucose and insulin level in HFD-fed and ND-fed mice. HFD-fed mice had similar levels of fasting glucose, but showed significantly higher fasting insulin levels. (n = 6; n.s: p>0.05; **: p<0.01). (C) glucose tolerance test and (D) insulin tolerance test of HFD-fed and ND-fed mice. HFD-fed mice showed impaired response to intraperitoneally injected glucose and insulin (n = 6; ***: p<0.001; ****: p<0.0001).
Fig 2.
Dysregulated insulin signaling but unchanged PrPC expression in HFD-fed mouse brains.
(A) Left: Western blot of pSer473-Akt and total Akt in ND- or HFD-fed mouse brains. Right: densitometric quantification of the Western blot showed significantly lower pSer473-Akt/Akt ratio in HFD-fed mouse brains (n = 3, *, p = 0.0280) (B) Left: Western blot of pSer9-GSK3β and total GSK3β in ND- or HFD-fed mouse brains. Right: densitometric quantification of the Western blot revealed a trend of reduced lower pSer9-GSK3β/ GSK3β ratio in HFD-fed mouse brains (n = 3, n.s p = 0.0890). (C) qRT-PCR of Prnp expression in HFD-fed and ND-fed mouse brains showed similar levels of Prnp mRNA (n = 3, n.s p>0.05). (D) Left: Western blot of PrPC in HFD-fed and ND-fed mouse brains. Right: densitometric quantification of the Western blot demonstrated a similar level of PrPC expression (n = 3, n.s p>0.05). (E) ELISA of PrPC showed similar level of PrPC expression in HFD-fed and ND-fed mouse brains (n = 3, n.s p>0.05).
Fig 3.
Unaltered prion pathogenesis in HFD-fed tga20 mice.
(A) Survival curve of HFD-fed and ND-fed tga20 mice intracerebrally inoculated with RML6. There was no significant difference in survival between the two groups (n = 6 per group; n.s.: p>0.05). (B) Left: Western blot for proteinase K resistant PrPSc in terminally sick mouse brains. Right: densitometric quantification of the Western blot revealed no significant difference between HFD-fed and ND-fed tga20 mouse brains (n = 3, n.s p>0.05). (C) Representative histology of terminally sick HFD-fed and ND-fed tga20 mouse brains stained for H&E and SAF84. There was no obvious difference between the two groups in lesion pattern, vacuolation, and PrPSc deposition. Scale bar = 200μm.
Fig 4.
Similar level of astrogliosis and microglial activation in terminally sick HFD- and ND-fed tga20 mice.
(A) Representative immunohistochemical staining for GFAP and Iba1 in brains of terminally sick HFD-fed and ND-fed tga20 mice. There was no detectable difference between the two groups in astrogliosis or microglial activation. Scale bar = 100μm. (B) Left: Western blot for Iba1 in terminally sick mouse brains. Right: densitometric quantification of the Western blot revealed no significant difference of Iba1 levels between HFD-fed and ND-fed tga20 mouse brains (n = 3; n.s.: p>0.05). (C) Left: Western blot for GFAP in terminally sick mouse brains. Right: densitometric quantification of the Western blot showed no significant difference of GFAP levels between HFD-fed and ND-fed tga20 mouse brains (n = 3; n.s.: p>0.05). (D) qRT-PCR of cytokines TNFα, IL-6 and IL-1β expression revealed similar expression levels of these cytokines in terminally sick HFD-fed and ND-fed mouse brains (n = 3; n.s.: p>0.05).