Measurement of Serum Corticosterone

Serum corticosterone of rats was measured using commercial ELISA kits (Cayman Chemical Company, Ann Arbor, MI). In order to explore long-term effects of repeated neonatal sevoflurane exposures on endocrine responses to stress during juvenile period, a subgroup rats of each experiment group (n = 6) were used for measurement of basal serum levels of corticosterone 30 min before the process of CFTS at P45. Another subgroup rats of each experiment group (n = 6) were used for measurement of serum levels of corticosterone 5 min after establishment of model of CFTS. Blood sampling was collected using the “tail clip” method. Specifically, the distal 0.5 mm of the tail was removed using a sterile scalpel blade, and blood was allowed to drain directly into a microcentrifuge tube. These rats used for for measurement of serum levels of corticosterone were not used in any other experiments since the blood sampling was a terminal procedure.