Rationale: Psychological stress is associated with an increased risk of cardiovascular diseases. However, the connecting mechanisms of the stress-inducing activation of the hypothalamic-pituitary-adrenal axis with atherosclerosis are not well-understood.
Objective: To study the effect of acute psychological stress on reverse cholesterol transport (RCT), which transfers peripheral cholesterol to the liver for its ultimate fecal excretion.
Methods and results: C57Bl/6J mice were exposed to restraint stress for 3 hours to induce acute psychological stress. RCT in vivo was quantified by measuring the transfer of [(3)H]cholesterol from intraperitoneally injected mouse macrophages to the lumen of the small intestine within the stress period. Surprisingly, stress markedly increased the contents of macrophage-derived [(3)H]cholesterol in the intestinal lumen. In the stressed mice, intestinal absorption of [(14)C]cholesterol was significantly impaired, the intestinal mRNA expression level of peroxisome proliferator-activated receptor-α increased, and that of the sterol influx transporter Niemann-Pick C1-like 1 decreased. The stress-dependent effects on RCT rate and peroxisome proliferator-activated receptor-α gene expression were fully mimicked by administration of the stress hormone corticosterone (CORT) to nonstressed mice, and they were blocked by the inhibition of CORT synthesis in stressed mice. Moreover, the intestinal expression of Niemann-Pick C1-like 1 protein decreased when circulating levels of CORT increased. Of note, when either peroxisome proliferator-activated receptor α or liver X receptor α knockout mice were exposed to stress, the RCT rate remained unchanged, although plasma CORT increased. This indicates that activities of both transcription factors were required for the RCT-accelerating effect of stress.
Conclusions: Acute psychological stress accelerated RCT by compromising intestinal cholesterol absorption. The present results uncover a novel functional connection between the hypothalamic-pituitary-adrenal axis and RCT that can be triggered by a stress-induced increase in circulating CORT.