Regulation Of Photoperiod On Testicular Structure And Function In Black-lined Hamsters

Background: The physiological characteristics and reproductive ability of seasonal breeding animals are regulated by many factors,such as light,temperature,food and so on,and the length of daily light(photoperiod)is one of the most important factors.The striped dwarf hamster(Cicetulus barabensis)is a small rodent living in the northern temperate zone.The reproduction of hamsters is regulated by seasonal rhythms strictly.And in the spring and autumn for the breeding peak,winter reproduction stagnation.The structure and function of the gonads are one of the most basic parameters for studying animal reproduction,and the development of the testis is very important for the reproduction of male animals.However,the specific mechanism by which the photoperiod affects the morphology and function of the testis is still unclear.The balance between autophagy and apoptosis is a key factor for maintaining tissue morphology and quality.Mitochondria perform multiple functions,and their functional changes affect various physiological and biochemical processes directly or indirectly in the body.To this end,this study used striped dwarf hamsters,an animal model,to study the effects of photoperiod changes on testicular morphology and function,and further explore whether these changes involve changes in apoptosis and autophagy levels,as well as the mitochondrial structure and changes in fission levels.Methods: Treated 20 males each group of three group adult striped dwarf hamsters separately under different photoperiods(short daylight,SD;moderate daylight,MD;long daylight,LD).After 8 weeks of light treatment,the hamsters were killed and dissected and took their testis:(1)Weigh the weight and the weight of the testis of striped dwarf hamsters,and calculate the organ coefficient of the testis at the same time.(2)Observe the tissue structure of the testis,use paraffin sections and HE staining techniques to detect the histological changes of the testis,and detect the development and degeneration of the testis by cell classification counting.(3)The apoptosisrelated proteins bax,bcl2,Cyto C,caspase3,and caspase9 of hamster testis were quantified to measure the changes in the level of testicular cell apoptosis.(4)Perform the protein quantification on the autophagy-related proteins LC3,P62,m TOR,and beclin1 of hamster testicular cells,and use frozen sections and immunofluorescence histochemistry(IFC)to detect the expression of LC3 and P62 to measure the changes in testicular cell autophagy levels.(5)Observe the structure of the cell nucleus and mitochondria by transmission electron microscopy(TEM).(6)Detect the content of FSH,LH and TTE related to reproduction by enzyme-linked immunoassay(ELISA).(7)Perform the protein quantification on testicular mitochondrial function and the fission-related proteins ATP synthase,CS,Drp1,Mff,Fis1 of hamsters,and measure the changes in mitochondrial function and the fission level.Results:(1)The weight and tissue quality of the hamsters in the SD group decreased,but there was no significant change in the tissue quality of the testes between the MD group and LD group,indicating that the testes atrophy under short light.(2)Serum LH,FSH and Fecal Testosterone in the LD group were decreased.(3)In the SD group,the diameter of the seminiferous tubules,the thickness of the seminiferous epithelium,the number of spermatogonia and Sertoli cells in a single tubule decreased in the SD group,it may be one of the reasons why the quality of testicles is decreased and the functional degradation of tissues and cells level in the SD group.(4)In the SD group of hamsters,the ratio of bax/bcl2 level increased in the testis,and the protein expression level of LC3?/LC3?remained unchanged,indicating that the apoptosis level in the testis increased under short light treatment,but the autophagy level maintaining stability indicates that the balance between apoptosis and autophagy has been broken,which may be one of the reasons for the decreased of testicular quality in the SD group.(5)In the LD group of hamsters,the ratio of bax/bcl2 and LC3?/LC3?levels were maintained stability in the testis,but the protein expression level of caspase3 increased,indicating that the mitochondrial apoptosis level and the autophagy level in the testes of the LD group remained unchanged,but the total level of apoptosis may be elevated.(6)In the SD and LD groups of hamsters,the protein expression levels of ATP synthase and citrate synthase(CS)remained unchanged in the testis,indicating that the mitochondrial function did not change.(7)In the SD group of hamsters,the protein expression levels of Drp1 and Mff increased,indicating that the level of mitochondrial fission increased at this time.Conclusion: The reproduction of the striped dwarf hamsters is tightly regulated by the photoperiod,and the development and degradation of the testicular structure determine the progress or stagnation of reproductive activities.Under long and short daylight,hamster reproduction stagnation or weakening is affected by different factors.Under short daylight,it is mainly manifested by the severe degradation of the testicular structure,while under long daylight,it is manifested by a large reduction in reproduction-related hormones.In addition,the balance between apoptosis and autophagy was broken.The changes in the level of apoptosis mediated the changes in the structure of the testis.At the same time,the mitochondria function in the testes was maintained under long and short light through the regulation of the level of mitochondrial fission.