The Functions Of Urine In Social Recognition And Urine-induced Cellular Activation In Main Olfactory Bulbs And Accessory Olfactory Bulbs Of Mandarin Voles

Chemical communication is important for the animal survival and reproduction, chemical cue play significant roles in animal behavioral, especially for the rodents. In this dissertation, the function of urine in sex recognition and individual recognition, kin discrimination were studied using behavioral observation method in behavioral choice maze, the function of two olfactory systems(the main olfactory system and the vomeronasal organ system) in chemical communication were researched using Fos expression as indicator of cellular activation. The chemical components and characteristics of mandarin vole urine were analyzed using solvent extracting and gas chromatography-mass spectrometry (GC-MS). Experimental animals were F1-3 generation of mandarin voles (Microtus mandarinus).The main results and conclusion of this cissertation are follows:1.The function of mandarin voles (Microtus mandarinus) urine in sex recognition: Urine from conspecifics rodents, containing volatiles and involatiles ( such as major urinary proteins), were important chemosignals in social information communication. The functions of mandarin voles urine in sex recognition were investigated using behavioral observation method. Through discriminating urine of mandarin voles of different sexes , by detecting the involatile molecules of urine (direct model), or by detected volatile molecules of urine (indirect model), We observed behaviors and scent marking of mandarin voles in direct model and those in indirect model.The investigation showed that mandarin voles showed significantly more preferences to the urines of opposite sexes, when mandarin voles contacted the urines directly. When contact were prevented, mandarin voles did not showed significantly preference to the urine of different sexes. Those results show that urine was an important chemical cue in sex recognition. Maybe mandarin voles counld attract opposite sex through involatile or low volatile molecules in urines. The sexual dimorphism of the behavioral discrimination to fresh urine in sex recognition were discovered.2.The recognition of mandarin voles (Microtus mandarinus) to the urine of novel and familiar individual :the functions of non-volatiles and volatiles in individual recognition of mandarin voles (Microtus mandarinus) were studied. The behaviors ofmandarin voles in direct model (contacting urine directly) with those in indirect model (being prevented from contacting urine directly) were compared in present research. When mandarin voles contacted the urine directly, they showed significantly more preference to the urine of familiar voles than those of the novel voles. When the voles was prevented from contacting urine directly, although voles showed differences in the odour choice preferences, they did not showed significantly difference in some behaviors like direct contact model. When mandarin voles were prevented from contacting urine, they could still learn and remember volatile molecules of the opposite sex. It suggested that the chemical signal of urine in individual recognition of mandarin voles contained in the volatiles or the complex mixture of non-volatiles. Perhaps the involatile molecules of urine were also important for the individual recognition.3.The mechanisms of mandarin voles (Microtus mandarinus) kin discrimination: In order to research the mechanisms of kin discrimination of mandarin voles (Microtus mandarinus), discrimination behaviors of mandarin voles for the urine of the sibling in same nest and the urine of strange non-sibling ,the urine of the sibling in different nest and the urine of strange non-sibling were investigated in a behavioral choice maze, it was investigated that the behaviors differences of the pups(45d)mandarin voles that brought up by the mother singly visited the urines of male parent and the urines of non-kin male mature vole in a behavioral choice maze. The results show mandarin voles showed significantly more preference to the urine of sibling voles in the same nest than those of the nonsibling voles. It suggested that mandarin voles can discriminate the urine of sibling in same nest and the urine of strange non-sibling. Although mandarin voles showed preference to the urine of sibling voles and father in the different nest than those of the nonsibling voles, the preference were not significantly as same as those of mandarin voles for the urine of sibling in the same nest. It suggested that the ability of mandarin voles discrimination kin using urine were weak when they never encountered sibling or male parent, although they could recognize their kin.In conclusion, it was the mechanisms of mandarin voles kin discrimination that association or familiarity recognition and phenotype matching. Kin recognition was the result of the heredity factors together with social experience, the heredity factors was the foundation of kin recognition, social experience was very important in kin recognition. Mandarin voles could complete kin recognition through involatile and volatile molecules of urine. We supposed that kinship of mandarin voles were codedusing the quality and quantity of the compounds in the urine.4. The research of compounds of the urine of mandarin voles {Microtus mandarinus): the chemical component of the urine of mandarin voles {Microtus mandarinus) were sampled using solvent extraction and then analysed by gas chromatography-mass spectrometry(GC-MS). The result show that the urines of male and female mandarin voles included many compounds. Those compounds were tentatively identified through searching in NIST27 database. In GC-MS results, thirty-four compounds were identified in male urines, but didn't found in female urines. Thirty-eight compounds were identified in female urines, but didn't in male urines. It was found that C4H8O3S (Thiophene-3-ol, tetrahydro-, 1,1-dioxide) in male urine, and C24H50S2(Disulfide, di-tert-dodecyl), C18H30O2S (2-Thiopheneacetic acid, dodecyl ester), C16H26O2S (2-Thiopheneacetic acid, decyl ester) in female urines. The difference of compounds were identified in male and female urines ,mybe it was the basic of chemical cues of sex recognition and individual recognition.5.The functions of the main olfactory system and the accessory system of mandarin voles {Microtus mandarinus): We used immunostaining for Fos to study different odor-induced neuronal activation in the olfactory systems of mandarin voles. When mandarin voles were esposured to urine of mandarin voles(in indirect model), Fos expression in the main olfactory bulb significantly were augmented and the accessory bulb were not significantly augmented. When mandarin vole exposured urine(in direct model), Fos expression in both the main olfactory bulb and the accessory bulb were augmented. When mandarin vole were exposured to formaldehyde odor, Fos expression was greatly enhanced in the main olfactory bulb and the accessory bulb, but only Fos expression of the main olfactory bulb were significantly augmented. These results showed that volatile pheromone in the urine of mandarin vole detected by the main olfactory epithelium, maybe volatile chemical cue singly couldn't be detected through the vomeronasal organ. Involatile pheromone molecules were detected by the vomeronasal organ. Non-pheromone odor were detected through the main olfactory epithelium.