Expeirmental Research Of Rosemary Essential Oil On Improving Learning And Memory In C57BL/6Mice Through Olfactory Pathway

ObjectivesIn this study, we established the olfactory epithelium damage model using zincsulfate(ZnSO4). In order to study the effect of rosemary essential oil of volatile aromaticsubstances treated on learning and memory through olfactory pathway in C57BL/6mice.On the other hand, in order to detect changes the amount of c-fos,thecholinesterase (AchE), glutamate receptors (GluR1) in the hippocampal CA1region ofmice after treated by the rosemary essential oil using immunohistochemistry method.Providing experimental basis for rosemary essential oils improving abilities of learningand memory,and Preliminary study the possible mechanism of rosemary essential oil toimprove learning and memory.MethodsThe C57BL/6mice were selected by neuroethology methods,and then some of themwere selected to be established the olfactory epithelium damage model. The C57BL/6mice were randomly divided into five groups: control group;sham operationgroup;model group (olfactory epithelium damage group); olfactory epithelium integrity+rosemary essential oil group and model+rosemary essential oil group. The medicinewas given via inhalation, by detected behavioral methods with water maze test andolfactory recognition memory experiment observate rosemary essential oils to the effectof the spatial learning and memory and olfactory recognition memory in mice. Andusing immunohistochemical methods to detect the hippocampal CA1region of mice ineach group c-fos, AchE and GluR1expression, and analysis the results of the grey value and the average absorbance values.Results1In the water maze test, compared to control group,sham operation group,modelgroup,olfactory epithelium integrity+rosemary essential oil group and model+rosemary essential oil group before sniffing, the latency was not statisticallysignificant (P>0.05). The latency of olfactory epithelium integrity+rosemaryessential oil group was cut down to sniff the7th and14th days, compared withcontrol group, there had statistically significance(P <0.05); Compared to shamoperation group, model group and model+rosemary essential oil group, in the7thand14th days the latency of control group was not statistically significant (P>0.05).2. In the olfactory recognition memory experiments, compared to control group,shamoperation group,model group,olfactory epithelium integrity+rosemary essentialoil group and model+rosemary essential oil group before sniffing, the latencywas not statistically significant (P>0.05). The latency of olfactory epitheliumintact+rosemary essential oil group was cut down to sniff the7th and14th days,compared with control group, there had statistically significance(P<0.05);Compared to sham operation group, model group and model+rosemary essentialoil group, in the7th and14th days the latency of control group was not statisticallysignificant (P>0.05).3The expression of c-fos in hippocampal CA1region in groups: With reference toThe Mice Brain Stereotaxic Coordinates,in hippocampal CA1region the c-fospositive cells were dyed in brown or brown punctate,and immunoreactive productswere mainly deposited in the nucleus. Compared with model group, sham operation group, model+rosemary essential oil group, in control group the differences ofpositive cells and the grey value were not statistically significant (P>0.05);Compared with control group, for olfactory epithelium integrity+rosemaryessential oil group the differences of positive cells and the grey value werestatistically significant (P <0.05).4The expression of AchE and GluR1in hippocampal CA1region in groups: Withreference to The Mice Brain Stereotaxic Coordinates, in the CA1region of thehippocampus AchE positive cells were brown, mainly located in the cytoplasm ofneurons and axons and dendrites,and proximal projections within the nucleus,uncolored or colored lighter. Compared with model group, sham operation group,model+rosemary essential oil group, the number of positive cells and the averageabsorbance values of control group were not significantly reduced (P>0.05);Compared to control group, the positive cell count and the averageabsorbance values of olfactory epithelium integrity+rosemary essential oil groupwere significantly reduced (P <0.05). Glutamate-positive cells were dark brownwithin the cytoplasm in the hippocampal CA1region, mainly located in thecytoplasm, cellular membrane,axons and dendrites,and proximal projections ofneurons within nucleus uncoloredand. Compared with model group, sham operationgroup, model+rosemary essential oil group, the number of positive cells and theaverage absorbance values of control group were not significantly up (P>0.05);Compared with control group, the number of positive cells and the averageabsorbance values of olfactory epithelium integrity+rosemary essential oil groupwere significantly up (P <0.05).Conclusions1.Rosemary essential oils improve the ability of learning and memory in C57BL/6 mice through the olfactory pathways.2.Inhalation rosemary essential oils improving abilities of learning and memory may beclosely related to the hippocampal CA1region in C57BL/6mice.3. Changes in the hippocampal CA1region of AchE and GluR1may mediate rosemaryessential oils to improve learning and memory in C57BL/6mice...