| Background:As we all know,obesity and hyperlipidemia as important factors of metabolic syndrome,seriously affect human health,and have become the focus of public health concerns around the world,and the two are often accompanied by each other inseparably.In modern society,excessive energy intake,reduced physical activity,and irregular work and rest,these dietary variations and changes in lifestyle have led to the occurrence of obesity.In recent years,the prevalence of obesity has shown a rapid growth trend both in developed and developing countries.Obesity can cause complex metabolism,endocrine and hemodynamic changes,which can lead to a variety of adverse consequences.Nutritional obesity is prone to visceral obesity,easily leads to metabolic disorders,and hyperlipidemia is usually associated with obesity.Lipid metabolism disorders and obesity are associated with unhealthy lifestyles and dietary patterns,eating too high calories easily causes all kinds of metabolic disorders.Obesity affects humans through a variety of ways.At present,there are a large number of overweight and obese people in the 20-40 year olds and women worldwide.Thus,if fertility in high-income or low-income countries is declining,the possible cause is the increase in global prevalence of obesity.Overweight and obesity can lead to a variety of diseases,including diabetes,coronary heart disease,shock,hypertension and obstructive sleep apnea.All of these symptoms,in addition to their own serious obesity,can affect the reproductive health of men and women.Previous studies have focused too much on the effects of obesity and hyperlipidemia on female reproductive systems,Insulin resistance,irregular menstruation,infertility,polycystic ovary syndrome,etc,recently for the male reproductive system influence research has become a hot topic and has got more and more attention by the medical profession and society.Obesity causes complex changes that may lead to diverse adverse outcomes.Reproductive abnormalities are common in obese individuals;in fact,it has been consistently documented that testosterone concentrations are decreased in obese men and that weight loss can revert this abnormality.Normal cell apoptosis is the way that the body tissues remove damaged cells.From the embryogenesis to the next body growth and development process,apoptosis plays an irreplaceable role.Germ cell apoptosis could eliminate damaged or abnormal chromosome reproductive cells,so that to ensure the accurate transmission of genetic information.At the same time,the number of germ cells can be controlled within the scope of support cells to ensure that the reproductive cells get enough nutrition and support.Excessive apoptosis,on the other hand,can cause the decrease in the number of germ cells,make the generation reduce and the body's fertility begins to decline.At the time of apoptosis,mitochondria plays an important role.The activity of nitric oxide synthase(NOS)increased,and the activity of Adenosine Triphosphate(ATP)was significantly decreased,and the cytoplasmic cytochrome C(Cyt c)(Caspase-3)and other apoptosis-related factors,causing apoptosis.Obesity and lipid metabolism disorders can lead to male reproductive function related to many factors,including apoptosis,especially the factors of mitochondria in apoptosis are particularly important.Male reproductive function is a clinical syndrome,caused by the decline of testicular testosterone and sperm capacity.The gold standard evaluation of male fertility is the spouse's pregnancy.The main clinical semen parameters,including concentration,shape,vitality can also be male fertility evaluation of the alternative indicators,and related reproductive hormone tests,such as total testosterone,free testosterone are also of reference value.Lipid metabolism can lead to lower levels of testosterone production in men,clinical manifestations of decreased libido,erectile dysfunction,decreased reproductive capacity.Male reproductive dysfunction is usually caused by decreased androgen,testosterone as the body's most important androgen,obesity and lipid metabolism disorders can lead to reduce testosterone synthesis and proliferation.In addition to spouse pregnancy,but also for testosterone,luteinizing hormone and other hormone levels of detection can evaluate male fertility.Common manifestations of reproductive dysfunction are mostly loss of libido,erectile dysfunction,which leads to decreased reproductive capacity.Testosterone and dihydrotestosterone are important androgen in the body.Testes are many testicular lobules that make up the vital organs that are male genital organs.Testicular lobular plate with curved fine tube.Refined tubules between the connective tissue within the larger cells is the testicular stromal cells,also known as Lattice cells.The marker enzyme of stromal cells is 3?-hydroxyhydrochlorohydrogenase.The interstitial seminiferous tubules and interstitials are formed by the support cells through a tight junction and support of extracellular basement membrane to form a layer of special structure-a blood testicular barrier,to protect the germ cells from the seminiferous tubules effect.Testicular stromal cells are the main synthesis sites for testosterone.Testosterone has important physiological and reproductive functions and non-reproductive physiological function.To act reproductive physiological function,testosterone has to maintain the male sexual function and sexual characteristics,the role of male attack consciousness.In non-reproductive physiological function,testosterone also promotes the three substances such as sugar,fat,protein metabolism and nucleic acid synthesis,affects the synthesis of many plasma proteins in the liver,stimulates the secretion of erythropoietin in renal tissue and triggers rhematopoietic stem cells into the original red blood cells.Testosterone can also stimulate the absorption of amino acids,promotes muscle fiber and bone growth,play an important role in cardiovascular system,respiratory system,nervous system differentiation.Testosterone synthesis and proliferation are affected by many factors.StAR,P450scc are important two rate-limiting enzymes in the process of testosterone production and they play an important role in the synthesis of testosterone.Cholesterol in the blood transport into the interstitial cytoplasm through the membrane membrane receptor.With the help of the the steroid synthesis of acute regulatory protein(StAR)and other factors cholesterol transfers from cytoplasm into the mitochondrial intima.Cholesterol in the interstitial cells is the raw material for the synthesis of testosterone.It can be derived from intracellular cholesterol and plasma derived cholesterol from the acetate,but in reality it is only normally derived from plasma cholesterol,circulating blood lipoprotein(human is low density lipoprotein,rat is high density Lipoprotein)in the ApoE-mediated adhesion of the lipoprotein receptor on the interstitial cell membrane,endocytosis into the cells,the cholesterol removed,and then stored in the fat drops.In addition,luteinizing hormone(LH)can act directly on the interstitial cell membrane of the luteinizing hormone receptor(LHR),start and regulate the synthesis of testosterone.The main pathway of cellular signal transduction-the AC-cAMP-PKA pathway plays an important role in it.Gonadotropin binds to the relevant receptor on the cell membrane and activates adenylate cyclase(AC)activity to upregulate intracellular cAMP levels and convert the extracellular signal into intracellular signaling.And cAMP as a second messenger to catalyze and activate protein kinase A(PKA),regulates the expression of testosterone synthesis-related genes.In summary,the maintenance of normal reproductive function requires a variety of hormone secretion,the normal functioning of cells and the lower moundpituitary on its regulation and other aspects of the role,and these factors affect each other,and some positive and negative feedback effect play a coordination function.By reviewing the literature,it was found that lipid metabolism disorders and obesity had a significant effect on reproductive function.With the popularity of precision medical concepts in recent years,the study on the pathogenesis of diseaseis is hotter.In this research,the apoptotic situation and of spermatogenic cells in rat testes and Cytc Caspase-3 proteins changes are estimated in the way of immunology,molecular biology and biochemistry,and the mechanism that Cytc proteins take part in the accommodation of spermatogenic cell apoptosis is explored.In the second part,we explored the mechanisms involved in high-fat group,such as the expression differences in StAR,P450scc and AC-cAMP-PKA pathway.Methods:Thirty health male SD(Sprague Dawley)rats about seven weeks were randomly divided into two groups.One was control group,and the other was obese high-fat group.General diet was given to the control group(n=]5),while high energy diet was given to the other group(n=15).The rats in the two groups measured body length(cm)after day 0 and 16 weeks of the experiment,and calculated Lee's index.All the rats were weighed once a week and recorded.All the rats in the two sets were sacrificed in 16 weeks and the weight of the adipose mass around the epididymis was weighed.The testis were obtained.ACA(automatic biochemical analyzer)was used to detect TG?TC?HDL-C(Triglyceride,Total Cholesterol,High-density Lipoprotein Cholesterol).PCR(Polymerase Chain Reaction)and immunohistochemistry were respectively used to measure the differernce of Cyt-c etc.MRNA and the protein between the two groups.LM(Light Microscopy)and TUNEL techniques were used to evaluate the apoptosis of the two groups.The expression of testicular LHR and testosterone biosynthesis enzymes(StAR,P450scc)in tests was measured by semi-quantitative polymerase chain reaction(RT-PCR)and Western blot.Testicular AC activity and cAMP levels weremeasured by using a[3H]cAMP assay kit and ELISA kit,respectively.Results:1.The establishment of obese and high-fat rat model with different diet inductionAt sixteen weeks old the body weight,body length,Lee's index,epididymal fat weight and blood lipid levels in obese high-fat group was higher than that in control group.2.Pathological observation of rat testisThe HE staining results showed that the nucleus of the spermatogonial nucleus in the testis was large and the eukaryotic expression was granulated,and the mitochondrial appearance was integral;the spermatid nuclear chromatin was dense and uniformity in the control group.However,the epithelial of testicular sperm cell was obvious damage,the gap of sperm cells and spermatocyte increased,and the connection disappeared;the seminiferous tubule was contracted,interstitial increases,and the sperm was retardant in the tubule of the high-fat group.The above results indicate that high fat can lead to changes in germ cell morphology.3.The state of cell apoptosis in rat testicular tissueHigh-fat group had a higer incidence rate in the apoptotic index of spermatogenic cells than the control group(P<0.05).Spermatogonia and spennatocytes were mainly found in apoptosis spermatogenic cells.The above results indicate that hyperglycemia can significantly increase the apoptosis of spermatogenic cells.4.Rat testis in Cyt c,caspase-3 mRNA and protein expressionCaspase-3 mRNA and protein increased significantly in the obese high-fat group in the way of RT-PCR and immunohistochemistry.The same results could be found in Cyt c mRNA and protein.These results indicate that the expression of Cyt c and Caspase-3 mRNA and protein in hyperlipidemia state significantly increased,and both are important factors in the process of mitochondrial apoptosis.Therefore,it is concluded that high fat may lead to apoptosis of spermatogenic cells through mitochondrial pathway.5.Serum hormones and histology in testesIn high-fat group,serum testosterone,SHBG,LH,and IGF-1 levels were significantly lower than that in the control group,and testicular testosterone level also decreased significantly.The weights of the testes and epididymides were lower in the high-fat group compared with the control group.Pathological lesions observed in high-fat group such as seminiferous tubules markedly increased diameters,and structural disturbance of spermatogenic cells with prominent vacuolization.The above results indicate that high fat can affect the male reproductive system by affecting the microstructure associated with testosterone synthesis and the gonadal organ.6.Testosterone synthetic enzymesHigh-fat markedly reduced mRNA and protein levels of StAR and P450scc in testes.No significant differences were found in the testicular mRNA and protein levels of LHR in the three groups.However,the high-fat rats had a significantly less testicular AC activity and cAMP level than that in the control group.It is tempting to consider that the decrease in serum LH in rats with high-fat might cause testosterone biosynthesis deterioration by affecting the expressions of testosterone synthetic enzymes through AC-cAMP-PKA pathway.Conclions:Obesity especially alimeniary obesity can increase apoptosis of germ cell in testicular seminoma.Cytc,caspase-3 system played an important part in the apoptosis induced by alimeniary obesity.The decrease of serum LH in rats with high-fat might cause testosterone biosynthesis deterioration by affecting the expressions of testosterone synthetic enzymes through AC-cAMP-PKA pathway. |
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