| Cricetulus barabensis,also known as Chinese striped hamster,is one of the dominant species of farmland rodents in northern China.It has caused great harm to agricultural production activities and participated in the spread of some epidemics,because of the strong reproductive capacity and large population.Therefore,it is necessary to strengthen prevention and control of its management.The Chinese striped hamster served as ideal experimental material in examining aggression behaviors is because which is a typical Palearctic fierce rodent and belongs to solitary animals.Investigating the behavioral regulation mechanism of striped hamsters has accumulated valuable information for studying the effects of striped hamster’s community structure,population density fluctuation and population diffusion mechanism,which is of great significance for the formulation of reasonable and efficient agricultural rodent control measures.5-hydroxytryptamine(5-HT) is an important signaling molecule and neurotransmitter regulating mental activities and animal behavior.It has been suggested relating to personalities in a wide range of species,such as hamster.Htr1 a and Htr1 b are two main receptors of 5-HT,which main expressed in the brain of mammalian.In order to explore the effects of 5-HT on the aggression behavior of different personality animals,explain its brain regulation mechanism from the receptor level,this study,used male striped hamsters as animal materials and Htr1 a and Htr1 b as the main target molecules,carried out the following experiments: to investigate the changes in aggression behavior of male hamsters with different personality and the differential expression of Htr1 a and Htr1 b mRNA in the brain,and to explanation the brain mechanism of Htr1 a and Htr1 b receptor regulation behavior.First,the striped hamsters captured in the farmland,Qufu City,Shandong Province were used as animal materials.Complete CDS region sequences of Htr1 a and Htr1 b of striped hamsters were cloned by RT-PCR,and Htr1 a and Htr1 b nucleic acid sequences and their amino acid sequence were analyzed by bioinformatics methods.The results of the study showed that: The clone of Htr1 a contained 1486bp(GenBank ID: MH169583) encoded 422 amino acids and Htr1 b contained 1414bp(GenBank ID: MH169584) encoded 386 amino acids in striped hamsters.The results of codon preference analysis indicated that Htr1 a and Htr1 b had unsynchronized use of synonymous codons but were not significant,indicating the conservation and func-tional stability of Htr1 a and Htr1 b.Physicochemical properties and functional sites analysis indicated that both Htr1 a and Htr1 b belonged to the G protein coupled receptor family.Both conform to the properties of membrane receptor proteins and are both hydrophobic proteins.They all have multiple protein binding sites and multiple functional sites.The predictions of second-level structure and three-level structure indicated that both of Htr1 a and Htr1 b had a highly conserved functional structure region.But Htr1 a is structurally stable,while Htr1 b is unstable.Homology alignment and cluster analysis showed that the sequences of Htr1 a and Htr1 b were all relatively conserved.The predictability analysis of the interaction between Htr1 a and Htr1 b indicated that the interaction between the two Htr structures may involved in the release of serotonin,thereby playing a role of regulating the 5-HT system.Second,under the laboratory conditions,the striped hamsters used in this study were purchased from Experimental Animal Center of Shanxi Medical University(license number: scxk(Jin) 2015-0001).The adult male Chinese striped hamsters were divided into two groups,the gentle group(n=12)and the violent group(n=12),based on their personalities by the times of bite and struggling in handling bag experiment.Used Panlab open field test experiment system to detect the opening behavior of animals,and used neutral arena video analysis system to detect the changes of the aggressive behavior between two individuals of the same personality.The results of the study showed that: between the gentle group and the violent group individuals,their Global Activity(P = 0.603),Maximum Velocity(P = 0.326),Resting Time(%)(P = 0.603),Moving Slow(%)(P = 0.488),Moving Fast(%)(P = 0.977),Hind limb standing times(P = 0.644),Central area residence time(P = 0.885),Number of modifications(P = 0.953) were no correlation.It shows that there are no differences in the opening behavior of striped hamsters with different personalities in the face of unfamiliar environments.The frequencies of fierce aggressive behavior(P = 0.001) and defensive aggressive behavior(P = 0.021) were significant higher in the violent group than that in the gentle group,while there was no significant difference in basic aggressive behavior(P=0.106) and social behavior(P=0.194) between gentle group and violent group.It shows that there are significant differences in the aggressive behavior of striped hamsters with different personalities.Spearman correlation analysis showed that the durations of animal struggling in Handling-bag experience was positively related to the frequencies of fierce aggression behavior(r = 0.686,P = 0) and defensive behavior(r = 0.482,P = 0.017).Finally,using the cloned Htr1 a and Htr1 b sequences to designed primers,and the relative expression of Htr1 a and Htr1 b mRNA in the brain of striped hamsters in different personality groups was detected by real-time PCR.The results showed that the durations of animal struggling in handling bag experiment is positively correlated with the expression of Htr1 a mRNA(r = 0.772,P = 0.003) in the brain respectively.And the relative expression of Htr1 a mRNA showed a significant positive correlation to the frequencies of fierce aggression behavior(r = 0.720,P = 0.008),nevertheless,there was no correlation was observed between the expression of Htr1 b mRNA and the frequencies of fierce aggression behaviorIn summary:(1)The complete CDS region sequences of Htr1 a and Htr1 b in striped hamsters were successfully cloned and the relationship between the two receptors was preliminarily predicted,to lay the foundation of the molecular biology for further exploring the function and mechanism of action of 5-HT system in striped hamsters.(2)The expression of Htr1 a mRNA was correlated with the aggressive behavior of male striped hamsters with different personality,which may be involved in the brain regulation of male animal aggression.The expression of Htr1 b mRNA was not related to the aggressive behavior of male striped hamsters with different personality.The result provides a new target for in-depth studies on the molecular mechanisms of brain regulation of animal aggression.Increase the understanding of the behavioral mechanism and life history of striped hamsters,and have important significance for the development of reasonable and efficient agricultural rodent control measures.It is of great significance to formulate reasonable and efficient agricultural rodent control measures,and has accumulated valuable information for studying the structure of striped hamsters’ community,population density fluctuation and population diffusion mechanism. |
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