Fig. 4. Tuberomamillary nucleus (TMN) orexin-saporin lesion did not change anesthetic sensitivity to propofol, pentobarbital, or ketamine. The dose–response curve for TMN orexin-saporin–lesion rats (blue lines ) and sham-lesion rats (red lines ) showing the percentage of animals that lost their righting reflex with intraperitoneally administered propofol (40–220 mg/kg) (A ), pentobarbital (15–55 mg/kg) (B ), and ketamine (40–220 mg/kg) (C ). There were no statistical differences in the ED50between orexin-saporin–lesion (crosses ) and sham-lesion (open circles ) rats (orexin-saporin: n = 12, sham: n = 8, P > 0.05). Effect of a single intraperitoneal injection of propofol (200 mg/kg) (D ), pentobarbital (40 mg/kg) (E ), and ketamine (200 mg/kg) (F ) on time to loss of righting reflex and time to return of righting reflex. There were no statistical differences between the orexin-saporin–lesion and sham-lesion rats (orexin-saporin: n = 10, sham: n = 7, P > 0.05). Ore-Sap = orexin-saporin.