Effects of acute stress on cardiac endocannabinoids, lipogenesis, and inflammation in rats

Objective: Trauma exposure can precipitate acute/post-traumatic stress responses (AS/PTSD) and disabling cardiovascular disorders (CVD). Identifying acute stress-related physiologic changes that may increase CVD risk could inform development of early CVD-prevention strategies. The endocannabinoid system (ECS) regulates hypothalamic-pituitary-adrenal (HPA) axis response and stress-related cardiovascular function. We examine stress-related endocannabinoid system (ECS) activity and its association with cardiovascular biochemistry/function following acute stress.

Methods: Rodents (n=8-16/group) were exposed to predator odor or saline; elevated plus maze (EPM), blood pressure (BP), serum and cardiac tissue ECS markers, and lipid metabolism were assessed at 24h and 2wks post-exposure.

Results: At 24h the predator odor group demonstrated anxiety-like behavior and had (a) elevated serum markers of cardiac failure/damage (brain natriuretic peptide [BNP]: 275.1 vs. 234.6, p=0.007; troponin-I: 1.50 vs. 0.78, p=0.076), lipogenesis (triacylglycerols [TAG]: 123.5 vs. 85.93, p=0.018), and inflammation (stearoyl delta-9 desaturase activity [SCD-16]: 0.21 vs. 0.07, p<0.001); (b) significant decrease in cardiac endocannabinoid (2-arachidonoyl-sn-glycerol, 2-AG: 29.90 vs. 65.95, p<0.001) and fatty acid ethanolamides (FAE: oleoylethanolamide, OEA: 114.3 vs. 125.4, p=0.047; palmitoylethanolamide, PEA: 72.96 vs. 82.87, p=0.008); and (c) increased cardiac inflammation (IL-1β/IL-6 ratio: 19.79 vs.13.57, p=0.038; TNF-α/IL-6 ratio: 1.73 vs. 1.03, p=0.019) and oxidative stress (thiobarbituric acid reactive substances [TBARS]: 7.81 vs. 7.05, p=0.022), that were associated with cardiac steatosis (higher TAG: 1.09 vs. 0.72, p<0.001). Cardiac lipogenesis persisted, and elevated BP emerged two weeks after exposure.

Conclusions: Acute psychological stress elicits ECS-related cardiac responses associated with persistent, potentially-pathological changes in rat cardiovascular biochemistry/function.