Analysis Of The Differential Protein Expression In Amygadaloid And Hypothalamic Regions Induced By Exposure To Cat Urine Odor For Norway Rats(Rattus Norvegicus)

Predation risk has direct and indirect effects on prey.Most rodents mainly rely on olfactory to sense chemical signals and appear differential defensive behavior and aggressive behavior.The neural circuit induced by predator odor is closely related to the hypothalamus,amygdala,nucleus terminalis,hippocampus regions.However,the proteins how to regulate the coordination of the internal loops in specific brain areas have not been reported yet.This study tried to analyse the differentially proteins expressed in the amygdala and the hypothalamus of Norway rats(Rattus norvegicus)and Wistar rats when they were acute or chronic exposed to rabbit urine odor and cat urine odor by two-dimensional gel electrophoresis and mass spectrometry.Meanwhile,some meaningful genes screened out were measured by fluorescence quantitative PCR and their functions were further clarified so as to supply the basical data for understanding the mechanism of prey responsing to the predator's odors.The following results were obtained:1)After acute exposure to urine odor,the levels of 14 proteins in amygdala tissue were significantly altered in cat urine odor exposure group compared with controls for Norway rats,while the levels of 17 proteins in amygdala tissue were significantly altered in cat urine odor exposure group compared with controls for Wistar rats.4 proteins were the same between two rats for Aspartate aminotransferase,Mitogen-activated protein kinase 1,Rieske Fe-S protein precursor,Ubiquitin carboxyl-terminal hydrolase;they were categorized into 3 classes including energy/metabolism,signal transduction and ubiquitin proteasome pathway.23 proteins were the different between two rats for Alpha-internexin,Triosephosphate isomerase 1,Ubiquitin-conjugating enzyme,Synapsin II,etc.;they were categorized into 5 classes including energy/metabolism,protein synthesis,cell structure,signal transduction and disease/denfence.The levels of 19 proteins in hypothalamus tissue were significantly altered in cat urine odor exposure group compared with controls for Norway rats,while the levels of 17 proteins in amygdala tissue were significantly altered in cat urine odor exposure group compared with controls for Wistar rats.3 proteins were the same between two rats for Tubulin beta-2B chain-like isoform X1,V-type proton ATPase catalytic subunit A,Creatine kinase U-type;they were categorized into 2 classes including energy/metabolism and cell structure.30 proteins were the different between two rats for Alpha-enolase,Rab GDP dissociation inhibitor alpha,Dihydropyrimidinase-related protein 2,etc.;They were categorized into 5 classes including energy/metabolism,cell structure,signal transduction,disease/denfence and ubiquitin proteasome pathway.2)After chronic exposure to urine odor,the levels of 26 proteins in amygdala tissue were significantly altered in cat urine odor exposure group compared with controls for Norway rats,while the levels of 33 proteins in amygdala tissue were significantly altered in cat urine odor exposure group compared with controls for Wistar rats.11 proteins were the same between two rats for ATP synthase alpha subunit precursor,Aspartate aminotransferase,Glial fibrillary acidic protein,Mitogen-activated protein kinase 1,Voltage-dependent anion-selective channel protein 1,Ubiquitin carboxyl-terminal hydrolase,Heat shock protein 72,NADH dehydrogenase,Phosphoglycerate mutase 1,Glutamine synthetase,Transcriptional activator protein;they were categorized into 5 classes including energy/metabolism,transcription,signal transduction,disease/denfence and ubiquitin proteasome pathway.43 proteins were the different between two rats for 14-3-3 protein zeta,4-aminobutyrate aminotransferase,6-Phosphogluconolactonase,Alpha-centractin,etc.;they were categorized into 5 classes including energy/metabolism,protein synthesis,protein destination/storage,cell structure,and disease/denfence.The levels of 36 proteins in hypothalamus tissue were significantly altered in cat urine odor exposure group compared with controls for Norway rats,while the levels of 33 proteins in amygdala tissue were significantly altered in cat urine odor exposure group compared with controls for Wistar rats.12 proteins were the different between two rats for Alpha-enolase,ATP synthase,Dihydropyrimidinase-related protein 2,Glial fibrillary acidic protein delta,Heat shock protein a8 protein,L-lactate dehydrogenase,NADH dehydrogenase,Neurofilament light chain protein,Peroxiredoxin 6,Phosphoglycerate mutase 1,Pyruvate dehydrogenase E1 component subunit alpha,Pyruvate kinase M,Ubiquitin carboxyl-terminal hydrolase PGP 9.5;they were categorized into 4 classes including energy/metabolism,cell structure,disease/denfence and ubiquitin proteasome pathway.45 proteins were the different between two rats for Phosphoglycerate kinase,Superoxide dismutase,Transcriptional activator protein,etc.;they were categorized into 6 classes including energy/metabolism,transcription,protein destination/storage,cell structure,signal transduction and disease/denfence.3)Among these identified proteins,Gfap and Mapk 1 in amygdala region and Prdx 6 and Ck in hypothalamus region were selected and their mRNA expression levels were measured by fluorescent quantitation PCR.In the amygdala region,the expression of Gfap was consistent in the expression of gene and protein level except in the Wistar rats group after chronic odor exposure and Norway rats group after chronic odor exposure.The expression of Mapk 1 was consistent in the expression of gene and protein level except in the male Norway rats group after chronic odor exposure.In the hypothalamus region,the expression of Prdx 6 was consistent in the expression of gene and protein level except in the male Norway rats and Wistar rats group after the acute and chronic odor exposure.The expression of Ck was consistent in the expression of gene and protein level except in the male Wistar rats group after the cat odor exposure.We concluded that both of Norway rats and Wistar rats produced the different proteins when whey exposed the odors of rabbit and cat,this meaned that both of rats could identify the rabbit urine odor and the cat urine odor,and produce oxidative stress to activate the defensive mechanism.So the down-regulation of the proteins related to energy metabolism and the up-regulation of the proteins related to oxidative stress could be the molecular basic for the prey initiating defensive strategy.