Serum corticosterone and blood glucose in rats after two jugular vein blood sampling methods: Comparison of the stress response

The purpose of this study was to evaluate stress by comparing blood glucose and serum corticosterone levels after repeated blood sampling over 2 h (fi ve time points) in anesthetized noncannulated rats to those of nonanestheti zed jugular-cannulated animals. Noncannulated rats underwent isofluorane an esthesia for the duration of the blood sampling at each time point. For bot h sampling methods, blood glucose concentrations increased after the initia tion of blood sampling, peaked at significantly increased (noncannulated ra ts, P < 0.01; cannulated rats, P < 0.01) concentrations at 0.5 h, and decre ased thereafter until the end of the assessment period. Despite the observe d fluctuations, blood glucose concentrations remained within normal ranges. Similarly, corticosterone concentrations increased significantly (noncannu lated rats, P < 0.01; cannulated rats, P<0.001) to peak values at 0.5 h. Ho wever, corticosterone was significantly lower at the 1- (P < 0.01) and 2-h (P < 0.05) time points in cannulated rats compared with anesthetized rats. Therefore, although both sampling methods are similar regarding blood gluco se and corticosterone peak concentrations and time-to-peak, stress was slig htly less in the cannulated rats than the rats that underwent repeated anes thesia.