Effects Of Neonatal Exposure To Lipopolysaccharides On Development Of Rat Testis

ObjectiveThe aim of the study was to observe the effects of neonatal rat exposure tolipopolysaccharide(LPS), and the potential harm of endotoxemia in neonatal rat onmale reproduction was also investigated.MethodsNormal healthy neonatal rats were selected for experimental use. Neonatal ratswere randomly organized into control and treatment group. Treatment group animalswere received intraperitoneal injection of75μg/kg LPS on every other day frompostnatal days4to12day, in all for5times，to establish endotoxin injury model andLPS was exchanged to equal volume saline for control animals. After treatment,animals of two groups were fed with normal diet until on postnatal21day, preputialseparation day (PSd),60day,77day. Bodyweight of rats were weighed, and thenanimals were sacrificed respectively. Bilateral testicles were collected, weighed, andconventional paraffin embedded testis slices were prepared. Slices were dyed withHematoxylin-eosin (HE) and immunohistochemical stained respectively, andpathological changes of testis tissue, expression distribution of proliferating cellnuclear antigen (PCNA), inducible nitric oxide synthase (iNOS) and vimentin(Vim)were observed under light microscopy.Results1. Bodyweight, testis weight, testis index, testis volume of both group animalsincreased with age rising. On preputial separation day, testis weight, maximumtransverse and longitudinal diameters, testis index of treatment group weresignificantly lower than that of control group, and differences between two groupswere significant (P<0.05). On postnatal60day, testis maximum longitudinal diameter of treatment group became smaller, and differences between two groups weresignificant (P<0.05).2. HE staining revealed that seminiferous tubules were lined evenly with a layerof regular seminieforuse epithelium in testis of control animals. And variousspermatogenic cells sequentially attached to seminiferous tubules. A large amount ofspermatozoons were observed in seminiferous tubules of60-and77-old postnatal dayrats. Diameter of seminiferous tubules increased with age rising. Comparing with thesame age rat in control group, diameter of seminiferous tubules in treatment groupbecame smaller. In treatment group, seminieforuse epithelium detached and becamethinner, and spermatogenic cells dearrangement was observed, even more seriously,spermatogenic cells defoliated from seminiferous tubules.3. Results of immunohistochemical technology analysis:(1) Positive vimentinwas observed in control group, along with basement membrane forming brown ring,and around sertoli cells strenching to lumen radially. Comparing with control group,expression of vimentin in treatment group decreased or disappeared.(2)PCNA-positive cells were mainly spermatogonia and primary spermatocytes. Positiveproducts located in nuclear, showed brown granules. Number of positive granules intreatment group was less than control group.(3) Expression of iNOS was observed insertoli cells, leydig cell, peritubularmyoid (PTM). Expression of iNOS in treatmentgroup sertoli cells and peritubularmyoid increased.Conclusions1. Neonatal rats exposure to lipopolysaccharides changed sertoli cells expressionand distribution of vimentin and destroyed sertoli cell cytoskeleton, resulted inspermatogenic cells detachment and injuryed process of spermatogenesis. This harmaction continued until rat becoming aldult.2. Neonatal rats exposure to lipopolysaccharides resulted in increasing iNOSexpression and decreasing PCNA expression，inferring expression of increasing iNOSresulted in excess nitric oxide (NO) production, which may be one of mechanism of sertoli cytoskeleton destroy, spermatogenic cells detachment, and disfunction ofspermatogenic cells proliferation by exposure to lipopolysaccharides.