Effect Of Orange Essential Oil On The Relieving Of Depression In Mice

Most essential oils have their special chemical composition and fragrance.They have a wide range of applications in many fields,such as food,medicine,cosmetics and so on.It is reported that rosemary and lemon grass play a critical role in the anti-depressant.Similarly,lemon essential oil was also reported with the same functions.While the effects of sweet orange essential oil(EO)on alleviating depression have not been reported.In this paper,the alleviation effect of EO on the model of depression in mice was investigated.The antagonistic effects and intake modes(gavage,sniffing and feeding)of EO on chronic mild unpredictable stress model(CUMS)and reserpine model.The indexs of the behavior test(sucrose preference test,open field test,forced swimming test),serum cholesterol,brain monoamine neurotransmitters(5-hydroxytryptamine,dopamine)were determined.Different intake methods of EO on the remission of mental depression in mice were analyzed.Additionally,the antagonistic effect of D-limonene on the reserpine model was also studied.The main contents and results are as follows:1.Study on the relieving effect of sniffing sweet orange essential oil on depressive symptoms in CUMS model mice.The depression in mice was induced using CUMS and up-alone model.The sucrose preference test,open field test and forced swimming test were performed to test the model.Then the CUMS model mice were processed by EO sniffing treatment.The results showed that the decrease on weight growth,curiosity and mobility,and struggle behavior in the desperate situation of CUMS model mice were observed.These depressive-like behaviors could also be relieved after the treatments of long-term sniffing(7 consecutive days)and short-term sniffing(1.5 h per day).In addition,symptoms of high TC,low HDL-C and high LDL-C of the CUMS model mice were also observed.This indicated that these negative effects on lipid metabolism in CUMS model mice could be slightly alleviated by sniffing EO.2.Study on the effects of three intake methods of EO on the antagonistic of reserpine model.The experimental group were treated with EO in three different ingestion methods:intragastric(0.1 m L/kg,0.05 m L/kg,0.025 m L/kg),sniffing,feeding(0.5% w/w,1% w/w,2% w/w).And then they were treated with intraperitoneal injection of reserpine(1 mg/kg).The antagonistic effect of ingestion methods,doses and feeding time on reserpine model(body temperature decrease,degree of eyelid drooping)was studied.Serum cholesterol and brain monoamine neurotransmitters were measured in the mice which were fed with EO feeds for 4 weeks.The results showed that specific symptoms of hypothermia and ptosis,as well as behavior inhibition,brain monoamine neurotransmitter depletion,dyslipidemia and other symptoms in reserpine model mice were observed.In addition,the antagonistic effects intragastric(0.05 m L/kg),sniffing and feeding(1% w/w,0.5% w/w)on reserpine model and depressive-like symptoms were observed.And the strongest alleviation fuction of EO on mental depression were observed in the intragastric group.A strong antagonistic effect of the reserpine model was obtained after four weeks' feeding with EO.The serum cholesterol levels decreased to reach the normal values.And the increase of the levels of 5-HT and dopamine were observed.This indicated that lipid metabolism could be benign regulated and the release of monoamine neurotransmitters were accelerated which could relive depression after EO feeding.3.Study on antagonistic effect of D-limonene on the mice's reserpine model.The mice were treated with sniffing or intragastric treatment at high(75 mg/kg),medium(50 mg/kg)and low doses(25 mg/kg)of D-limonene.And then they were treated with intraperitoneal injection of reserpine(1 mg/kg)to construct a mouse reserpine model.The effects of intragastric and sniffing treatments on antagonistic characteristics(body temperature decrease,degree of eyelid drooping)and behavior tests(open field test,forced swimming test)were analyzed.The contents of monoamine neurotransmitters and corresponding hormones in the brain were detected subsequently.The changes of hypothalamic lesions and paraventricular nucleus CRF immunohistochemistry were also analyzed.The results showed that a strong effect of intragastric and sniffing D-limonene on the antagonistic characteristics of reserpine model and remission of depressive-like behavior in the mice were observed,The body temperature decreased and the degree of eyelid drooping were restored to normal values(blank control group),and the mobility and curiosity increased.The contents of 5-HT,dopamine increased.While ACTH and TH decreased after the treatment.CRF content has downregulated,and experiment group showed a protective effect from hypothalamus lesions which was caused by reserpine model.What's more,the result indicated that depressive-like behaviors could be efficiently relieved by intragastric with low and medium dose(25 mg/kg,50 mg/kg)of D-limonene.4.Determination of aroma compounds in the sniffing environment and the absorption of aromas in the mice brain.Volatile aroma components in the sniffing atmosphere were measured by headspace direct injection and solid phase microextraction.Four characteristic aroma components in the EO(D-limonene,?-pinene,linalool,?-myrcene)were measured in the mice's brain after sniffing or intragastric treatments for 1 week.The results showed that the main volatile substances in the sniffing atmosphere were D-limonene(90%),followed by ?-pinene(5.98%)and ?-terpinene(2.97%).The content of D-limonene(main compounds in sniffing atmosphere)had a sharp decline at the first day and maintained balance at the following 4 days.Strong absorption on the content of the four compounds were observed in the intragastric group.In addition,the highest contents of D-limonene and relative lower contents of linalool in the brain were observed.