Effects Of Intraperitoneal Injection Of Nickel Sulfate On Pituitary Function,histomorphology And Caspase-3 Protein Expression In Rats

Objective:In this study,rats were exposed to Nickel Sulfate（NiSO₄）by intraperitoneal injection for 40 d,and the morphological and morphological changes of rat pituitary tissue were observed by detecting relevant indexes of rat pituitary function under nickel exposure environment,so as to evaluate the toxic effects of NiSO₄ on rat pituitary function and tissue damage.By detecting the expression of apoptosis protein Caspase-3 in rat pituitary tissue to discuss the influence of environmental nickel exposure on pituitary metabolism and its possible mechanism.Method:1.Twenty-four adult healthy male SPF Wistar rats were randomly divided into normal control group（group C,saline 5.0 m L/kg）,low dose nickel sulfate group（group L,NiSO₄ 2.5 mg/kg）,medium dose nickel sulfate group（group M,NiSO₄ 5.0mg/kg）and high dose nickel sulfate group（group H,NiSO₄10.0 mg/kg）.Every group had six rats.The rats were injected intraperitoneally for 40 days,and they ate and drank freely.The amount of food,water and body weight of the rats were recorded daily,and the activities of the rats were observed.The next day after exposure,blood and pituitary tissue samples of rats were taken.2.Centrifuge rat serum at first,then determine the levels of Thyroid stimulating hormone（TSH）,Growth hormone（GH）,Adreno cortico tropic hormone（ACTH）,Prolactin（PRL）,follicle-stimulating hormone（FSH）,luteinizing hormone（LH）and cortisol levels by ELISA.3.The pituitary tissues of rats were fixed in 10%formalin for 24 h,embedded in paraffin,sectioned and stained with HE.The morphological changes of pituitary tissues of rats in each group were observed after exposure to NiSO₄.4.The pituitary tissue was sectioned,and the expression of Caspase-3 protein in rat pituitary tissue exposed to different doses of NiSO₄ was detected by immunohistochemistry.Results1.Changes of pituitary hormone levels in rats:Compared with the control group,TSH levels in low-dose and middle-dose NiSO₄ groups were significantly lower（P<0.05）,but there was no significant change in high-dose NiSO₄ groups（P>0.05）;The level of LH increased with the increase of the dose of NiSO₄,and there was a significant difference between the high-dose NiSO₄ group and the control group（P<0.05）.There was no significant difference in GH,PRL,FSH,ACTH and cortisol levels among the groups.2.Histopathological changes of rat pituitary:Pituitary tissue sections of rats in control group and low-dose NiSO₄ group showed normal pituitary structure;A small number of scattered lymphocytes infiltrated in pituitary tissue of middle and high dose NiSO₄ group,and the cells were mostly arranged in a funicular shape,with no obvious abnormality in morphology.3.Expression of Caspase-3 protein in pituitary tissue:Caspase-3 protein is mainly located in cytoplasm,and a small amount is located in nucleus,with diffuse brown granules as positive staining.Compared with the control group,there was no significant difference in the expression of Caspase-3 in pituitary tissue of each NiSO₄-exposed group.Conclusion1.Subchronic intraperitoneal injection of NiSO₄ can cause some pituitary hormone levels to change.2.Subchronic intraperitoneal injection of NiSO₄ may induce slight inflammatory changes in pituitary tissue of rats.3.After subchronic intraperitoneal injection of NiSO₄,the apoptotic protein Caspase-3 in rat pituitary tissue did not change.