Effect of Propofol on ERK1/2 expression during day times in the rat hippocampus

Background: Anesthetics are responsible for imparting many effects on the central nervous system. We hypothesized that short duration anesthetics may have varied effects at different time of the day. Propofol (short duration anaesthesia) has showed circadian variation in loss of righting reflex during 24 hours of the day.Methods: Characterization of the effects of propofol anaesthesia on ERK1/2 in hippocampus at two different times of the day was performed. Male rats received either an intra-peritoneal injection of 120 mg/kg of propofol to set short-duration anaesthesia state (20-30 minutes) or the equivalent amount of the lipidic solvent as controls. For both groups of animals, anaesthesia or control, the injections were performed either at ZT0 or at ZT12. One hour following the injection, the animals were euthanized; the brains were removed and immediately frozen. The amount of ERK1/2 was assessed by using immunohistochemistry on brain sections.Results: The amount of ERK1/2 density was significantly decreased (P