Effects of prolonged cold stress on vascular function in guinea pigs with atherosclerosis.

Research objective: This study explored the effects of long-term cold stress on aortic vascular function in guinea pigs. Research Methods: Hartley guinea pigs (n=32) were divided into following groups: atherosclerosis (AS), cold stress (CS), and menthol-stimulated (M) and control (C). On days 1, 15, 30, 45, and 60, guinea pigs in the AS, CS, and M groups were intraperitoneally injected with bovine serum albumin. The C group was provided with maintenance feed and room-temperature water. The AS group was provided with a high-fat diet and room-temperature water. The CS group was maintained in a refrigerator at 4 °C，while providing a high-fat diet and iced water. The M group was administered menthol solution, and provided with a high-fat diet and room-temperature water. The modeling period lasted for 120 days. On day 121, abdominal aortic sera and aortic samples were obtained after intraperitoneal injection of sodium pentobarbital. Blood rheology tests were conducted to assess blood adhesion, biochemical tests to assess lipid levels, and enzyme-linked immunosorbent assays to detect serum nuclear factor-κB, tumor necrosis factor-α, and interleukin-1β, and endothelial nitric oxide (NO) synthase, NO, and endothelin-1(ET-1) in aortic tissue. Hematoxylin and eosin and Oil Red O staining were used to examine pathologic changes in the aorta, western blotting to detect TRPM8 and PKG protein expression, qPCR was used to measure VCAM-1 mRNA expression level. Research findings: Prolonged exposure to cold stress exacerbated lipid-metabolism disorders in guinea pigs fed a high-fat diet, increased aortic vascular cell adhesion, and exacerbated vascular inflammation, leading to endothelial injury, ultimately worsening pathologic changes associated with aortic atherosclerosis.