The Retardation Of Nervous Development Of Eugenol Or Toluene Olfactory Imprinting And The Related Mechanisms

Backgrounds and ObjectivesThe nervous development could get influenced by the surroundings during the early infancy and thus, the life-long behavior alterations could be observed. Some examples could be come up with. Visual deprived mice or the neonatal maternal separation mice could be observed with alteration of brain function. Sensory experience or deprivation during an early critical period results in substantial plasticity and is a crucial factor in establishing the mature circuitry. Basically, the complex exposure experience could benefit the brain plasiticiy and development, the poor or deprived experience could retard the CNS development. Based on the importance of infant exposure surroundings , the odor exposure may also influence the adult performances.Olfactory imprinting theory was based upon the infant exposure surroundings. For example, the supernatural sense of smell of salmon is crucial in the maintance of their life cycle,callow birds'odor-related imprinting memory after their mothers'incubation. The mechanisms involves the role of memory on the odor during early infancy. Thus, the olfactory imprinting theory was come up with by the neurobiologists.Based upon the theories of olfactory imprinting and the special olfactory pathway, we come up a hypothesis that if a single given odor could be transmitted into certain limited brain area. Considering it is just during the very early life when the odor imprinting could make a life-long effect on the life-long behavior alterations , the single odor should be given during the neonatal stage to keep the other odorant gene in a state of silence. We were wondering how the single odor could influence the adult behavior performances and if the single odor during the early infancy could make a imprinting trace. These may help us make a further understanding on the relationship between the odorant stimulus during the early infancy and the cerebral development. To observe the neuroethological performance of the adult mice , which had inhaled a given odor-eugenol or toluene at new-born stage.The first part: The given odor imprinting model: two groups of the infant mice forced to inhale the single, given odorMethods The new-born mice were divided into three groups : The Positive eugenol group inhaling eugenol,the negative toluene group inhaling toluene and the control breathing into nature air. Both the positive eugenol group and the negative toluene group were divided into three subgroups according to the different time interval:1w,2w,3w. Six weeks later, several neuroethology experiments were done.Results The distinguishing odor experiment was to observe the olfactory imprinting performance . If the olfactory imprinting performances could be observed, the model could be judged as a correct one.The second part: The neuroethological performances on the adult miceMethods: Six weeks later, several neuroethology experiments were done. The odor preference test was to test the odor imprinting towards the given odor during the early infancy. Other learning ability-related ethological experients such as : the distinguishing odor experiment,the six-arms maze and Morris water maze were to evaluate the learning and memory ability of the mice forced to inhale the given odor during the early infancy.Results: From the results of the odor preference test, we could know that the proportions of mice in preferring to the eugenol odor of eugenol group were higher than that of control group showing the eugenol preference performance;The proportions of mice in preferring to the toluene odor of toluene group were higher than the control group showing the toluene preference performance.The adult mice showed fiece preference to the odor that had been inhaled during the neonatal stage and they had special ability to distinguish the given odor ,however, week learning-and-memory ability compared to the control group;From the comparsion of the datas in the distingusihing odor experiment and six-arms experiment, both the negative groups and the positive groups had weaker ability (p<0.05) to identify and memory pepper smelled chocolate compared with the control group.From the comparsion of the the morris maze, both the negative groups and the positive groups showed that weaker space learning& memory ability(p<0.05) compared with the control group.The third part : The mechanisms involving the retardation of ethology performances in adult mice induced by a given,single odor during early infancy.Methods: The test of electrophysiology is used to detect olfactory nerve-evoked field potentials by eugenol-inhaling in different concentration and compare the spontaneous potential with the induced potential after inhaling different eugenol, air, toluene. Then, each mouse was sacrificed and brains were removed. The slices of hippocampus and cortex were stained with HE's staining, Nissl's staining and detected the expression of ChAT, GABA and Glu by immunohistochemistry.Results: The consequence of electrophysiology test is that OB,hippocampus,amygdala,hypothalamus can bring out different olfactory nerve-evoked field potentials when the mice forced to inhale eugenol during early infancy. The amygdala;septal nuclei,hippocampus,hypothalamus could bring out different odor nerve-evoked field potentials when the mice forced inhale toluene during early infancy mice inhaling toluene. According to the immunohistochemistry results, the mechanisms involving the retardation of ethology performances in adult mice is known to relate to the decrease of SYP,NMDAR and other such as ChAT, Glu. However, the GABA could be observed with an increase.Conclusions1. The life performance of a single olfactory imprinting, no matter what charcteristic of the odor is, could be observed .2. A poor odor environment , during the early infancy could block cerebral development while the environment teemed with plentiful odors could benefit it.3. The consequence of electrophysiology test showed that the eugenol imprinting may be based upon the special eugenol olfactory pathway that directed to hippocampus; the toluene imprinting may be based upon the special eugenol olfactory pathway that directed to the amygdala;septal nuclei,hippocampus,hypothalamus and other areas.4. The mechanisms involving the retardation of ethology performances in adult mice is known to relate to the changes of SYP,NMDAR and other such as ChAT,Glu,GABA when compared with the control group.