title: The effect of ghrelin on MK-801 induced memory impairment in rats.
abstract: Accumulating evidence indicates that the brain-gut peptide ghrelin which is expressed in hippocampus improves memory and learning processes. The MK-801, a noncompetitive NMDA receptor antagonist, has also shown amnesic properties in animal model. The current study was to find out whether intracerebroventricular administration of ghrelin can prevent amnesia induced by MK-801 in rats. A week after the surgery, during which cannuals were implanted in the lateral ventricular, the animals were trained and tested in a step-through type passive avoidance task. Memory retrieval was measured by step-through latency (STL) and total time in dark compartments (TDC). In the first series of experiments, we established a dose-response relationship for ghrelin on the passive avoidance paradigm. In the second set of experiments, animals were divided to two groups. In the first group, MK-801 (0.075, 0.15 and 0.3mg/kg) was injected intraperitoneally (i.p.) immediately after the acquisition session and in the second group MK-801 (same doses) was injected (i.p.) 30 min before the retention session. Analysis of data showed that in both groups, MK-801 impaired learning and memory. In the third set of experiments, administration of ghrelin (200 ng/rat) right after the acquisition session (i.e. before MK-801 injection) improved the MK-801 induced memory impairment, but administration of ghrelin before retrieval session did not affect the MK-801 induced memory impairment. These results show an interaction between ghrelin and glutamatergic system. A novel finding in this study is that ghrelin can prevent amnesia produced by NMDA antagonist in rats when injected in post-training phase.
authors.affiliation: Physiology Department, Faculty of Paramedical Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran. fgoshadrou@yahoo.com
authors.forename: Fatemeh
authors.initials: F
authors.lastname: Goshadrou
authors.forename: Mojtaba
authors.initials: M
authors.lastname: Kermani
authors.forename: Abdolaziz
authors.initials: A
authors.lastname: Ronaghi
authors.forename: Samad
authors.initials: S
authors.lastname: Sajjadi
mesh_terms: D000647:Amnesia / Q000139:chemically induced / Q000517:prevention & control*; D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects; D016291:Dizocilpine Maleate; D004305:Dose-Response Relationship, Drug; D054439:Ghrelin / Q000008:administration & dosage* / Q000502:physiology; D007276:Injections, Intraventricular; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism; D012153:Retention, Psychology / Q000187:drug effects
chemical_list: D054439:Ghrelin; D016194:Receptors, N-Methyl-D-Aspartate; D016291:Dizocilpine Maleate