Chronic Administration of Methamphetamine Aggravates Atherosclerotic Vulnerable Plaques in Apolipoprotein E Knockout Mice Fed with a High-cholesterol Diet.

Background: It has been observed previously that chronic methamphetamine (METH) administration could upregulate neuropeptide Y (NPY) expression and promote atherosclerotic formation in apolipoprotein E knockout (ApoE-/-) mice fed with a normal cholesterol or high diet and NPY might be involved in the pathogenesis of METHinduced atherogenic effects through NPY Y1 receptor pathway. Vulnerable coronary atherosclerotic plaque (VP) is a critical pathological finding responsible for the acute coronary syndrome (ACS). In this study, we explored whether METH abuse could aggravate the formation of VP in ApoE-/- mice fed with high cholesterol diet.

Objective: The purpose of this study was to observe if chronic METH administration could aggravate vulnerable plaque (VP) formation in ApoE-/- mice fed with a highcholesterol diet.

Methods: Male ApoE-/- mice fed with a high-cholesterol diet were intraperitoneally injected with normal saline (NS) or 8 mg/kg/day METH (M8) for 24 weeks. Body weight was monitored from baseline to 24 weeks at 2 weeks intervals. After 24 weeks of treatment, plasma lipid variables were measured. Movat's staining and immunohistochemical staining were performed on frozen sections of the aortic roots to calculate VP percentage and intraplaque hemorrhage (IPH) percentage and detect expression of NPY, vascular endothelial growth factor (VEGF), and CD31. In vitro, the expressions of Y2R, VEGF, and CD31 were detected by immunofluorescence staining in aortic endothelial cells incubated with PBS, 100μM METH, 10nmol NPY, or 100μM METH plus 10nmol NPY for 12 hours.

Results: The CD31 positive area, percentage of IPH, VP, and the expressions of NPY and VEGF were significantly increased in the M8 group than in the NS group. In vitro, the expressions of Y2R, VEGF, and CD31 were significantly increased in the METH+NPY group than in the PBS, METH, and NPY groups and these effects could be blunted by treatment with a Y2R antagonist or DPPIV inhibitor.

Conclusion: Chronic METH administration could aggravate VP in ApoE-/- mice fed with a high-cholesterol diet, possibly through upregulating vascular NPY and VEGF expression and promoting angiogenesis and vessel rupture in atherosclerotic plaques. Our findings indicated that increased VP formation might contribute to the development of acute coronary syndrome post-chronic METH abuse by activating DPPIV/NPY/Y2R pathway.