i.r. Beta-endorphin, corticosterone, cholesterol and triglyceride concentrations in rat plasma after stress,...

Plasma i.r. beta-endorphin, corticosterone, cholesterol and triglyceride concentrations were determined in male Sprague-Dawley rats after exposure to running or swimming stressors or after surgical ablation of the cingulum bundle. While cingulotomy alone altered only the plasma triglyceride concentrations, the combination of cingulotomy plus running stress significantly increased plasma i.r. beta-endorphin and triglyceride concentrations above those seen in animals receiving only a running stress. Triglyceride concentrations in cingulotomy plus swimming stress were significantly elevated above those in animals receiving a severe stress only. While the exposure to running and swimming increased plasma beta-endorphin significantly above control levels, plasma corticosterone was not affected by these stressors. Changes in plasma cholesterol and triglycerides were also differentially affected by cingulotomy or stress exposure. These results indicate that various stress hormones are affected differentially by exposure to various experimental procedures which are employed as stressors.