title: Biphasic effect of citral, a flavoring and scenting agent, on spatial learning and memory in rats.
abstract: Although some central effects of citral have been reported, cognitive effects on spatial memory have not been investigated. The evidence showed that citral can regulate the synthesis of retinoic acid (RA), which exerts a vital function in the development and maintenance of spatial memory. In this study, we applied Morris water maze to test the effect of citral on animals' spatial learning and memory. To elucidate the mechanism of this effect, we also measured the retinoic acid concentration in rats' hippocampus by high performance liquid chromatography (HPLC). Our data implied biphasic effects of citral. The low dose (0.1 mg/kg) of citral improved the spatial learning capability, and enhanced the spatial reference memory of rats, whereas the high dose (1.0 mg/kg) was like to produce the opposite effects. Meanwhile, the low dose of citral increased the hippocampal retinoic acid concentration, while the high dose decreased it. Due to the quick elimination and non-bioaccumulation in the body, effects of citral on spatial memory in this study seemed to be indirect actions. The change in hippocampal retinoic acid concentration induced by different doses of citral might be responsible for the biphasic effect of citral on spatial learning and memory.
authors.affiliation: Department of Pharmacology, Wuhan University School of Basic Medical Science, Wuhan, Hubei 430071, China. yang_zheqiong@yahoo.com
authors.forename: Zheqiong
authors.initials: Z
authors.lastname: Yang
authors.forename: Jinlei
authors.initials: J
authors.lastname: Xi
authors.forename: Jihong
authors.initials: J
authors.lastname: Li
authors.forename: Wen
authors.initials: W
authors.lastname: Qu
mesh_terms: D000080462:Acyclic Monoterpenes; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D003627:Data Interpretation, Statistical; D004305:Dose-Response Relationship, Drug; D005421:Flavoring Agents / Q000008:administration & dosage / Q000494:pharmacology*; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism; D007202:Indicators and Reagents; D008297:Male; D018782:Maze Learning / Q000187:drug effects*; D008568:Memory / Q000187:drug effects*; D039821:Monoterpenes / Q000008:administration & dosage / Q000494:pharmacology*; D009812:Odorants; D051381:Rats; D017207:Rats, Sprague-Dawley; D014212:Tretinoin / Q000378:metabolism
chemical_list: D000080462:Acyclic Monoterpenes; D005421:Flavoring Agents; D007202:Indicators and Reagents; D039821:Monoterpenes; D014212:Tretinoin; C007076:citral