Anesthesia of rats on postnatal days (P) 4, 5, or 6 with propofol results in long-term heightened endocrine activity. Histograms show serum levels of corticosterone in >P80 rats of both sexes during stress (5 min after completion of the prepulse inhibition [PPI] test) and at rest (3 to 5 days after completion of the PPI test). Numbers of animals per treatment group: (A) negative control (n = 4), saline (n = 10), intralipid (n = 5), and propofol (n = 15). *P < 0.001 versus all other groups. (B) Propofol-exposed males (n = 5), propofol-exposed females (n = 10). (C) Negative control (n = 4), saline (n = 6), and propofol (n = 7). *P = 0.038 versus other groups. (D) Histograms showing serum levels of corticosterone under stress in rats that received bumetanide (1.82 mg/kg, intraperitoneally) before anesthesia with propofol at P4 to P6 (n = 13, *P = 0.015). The rats in the propofol group were the same as those in A. (E) Histograms showing serum levels of corticosterone under stress in rats that received corticosterone (0.2 mg/kg, intraperitoneally) at P4 to P6 (n = 6). The rats in the negative control and saline groups were the same as those in A. *P < 0.01 versus all other groups.