Effects Of The Animal Odors From Different Species On The Stress Hormone And Sex Hormone Of Norway Rats (Rattus Norvegicus)

Prey has acquired an innate response to their predators during the long evolutionary history. Odors from urine or fur of an animal contain a lot of information about this species. Prey may take odors from their predator as a predation risk and avoid being preyed by changing their behavioral and, consequently, physiological responses, which is one of the survival strategies. Wild Norway rats (Rattus norvegicus), the first generation of laboratory bred Norway rats, and Wistar rats were used to investigate the hormonal responses to the odors of rabbit (Lepus capensis), badger (Meles meles), domestic cat(Felis catus) and weasel(Mustela sibirica). Results showed that:1) There were no significant difference for the plasma CORT level (corticosterone) and ACTH (Adrenocorticotropic Hormone) of wild Norway rats between the rabbit odor and control conditions, but the plasma CORT and ACTH of wild Norway rats exposed to the three natural predator odors were significantly differ with control respectively. The plasma CORT and ACTH of wild Norway rats under badger、cat and weasel odor conditions were significantly higher than those under rabbit odor condition. The plasma CORT and ACTH of male wild Norway rats under cat and weasel odor conditions were significantly higher than those under badger odor condition; The plasma CORT and ACTH of female wild Norway rats under cat odor condition were significant higher than those under badger odor condition. Upon exposure to predator odor for10min, there were no significant difference for the plasma T (Testosterone) and E2(Estradiol) of the wild Norway rats among different odors. 2) Compared to the control odor condition, the plasma CORT and ACTH of the laboratory bred Norway rats under different odor conditions significantly increased; The plasma CORT and ACTH under cat odor condition were significant higher than those under rabbit and badger odor conditions. There were no significant difference for the plasma T and E2of the domestic Norway rats among the different odor conditions.3) Compared to the control odor condition, the plasma CORT and ACTH of Wistar rats under three odor conditions significantly increased. There were no significant difference for the plasma CORT and ACTH of the Wistar rats between different odors. Exposure to predator odor for10min, there were no significant difference for the plasma T and E2of Wistar rats among the different odor conditions.4) After odor exposure for different period, the plasma CORT and ACTH of Norway rats were significant higher than control condition, and the trends was first increased and then decreased. The plasma E2after1d、3d、6d and9d odor exposure of female Norway rats were significantly lower than the control condition. There were no significant difference for the plasma T between1d、3d、6d and9d odor exposure of male Norway rats and the control condition. Compared with the control condition, the plasma IgG of Norway rats significantly decreased.Form above; it is clear that PA axis is being stimulated upon exposure of Norway rats to different predator odors. The domestic Norway rats considered cat and weasel odor as a predator, and considered rabbit and badger odor as annoyer. Our experiments indicated that Wistar rats were very sensitive to external environment. The plasma stress hormone after different period of odor exposure were first increased and then decreased, but the plasma CORT and ACTH on day9still higher than those on control condition. This indicates that the endocrine response to cat odor didn’t habituate over time.