Effect of Ghrelin on Thymus Growth and Development of African Ostrich Chicks
In order to investigate the effects of exogenous growth hormone-releasing peptide(Ghrelin)on thymus growth and development of African ostrich chicks,sixteen 7-day-old African ostrich chicks were randomly divided into 4 groups with 4 repli-cates per group.After feeding for 33 days,different doses of Ghrelin(0,10 µg/kg,50 µg/kg,100 µg/kg)were injected intrave-nously into the toe veins.And the thymus tissues were taken for paraffin embedding and slicing.HE staining,TUNEL technique,immunohistochemical staining and qPCR technique were used to study the morphology,thymocyte apoptosis and Foxn1 gene.The results showed as follows:① Compared with the control group,the thymus index and weight of African chicks were both de-creased after the injection of 10 µg/kg,50 µg/kg and 100 µg/kg Ghrelin(P<0.05),and the thymus index of the 100 µg/kg dose group was significantly lower than that of the 50 µg/kg dose group(P<0.05).② After the injection of different doses of Ghrelin,the morphology and structure of thymus changed significantly with the increase of dose.The thickness of thymic cortex and the ra-tio of cortex to medulla area were significantly reduced in the 50 µg/kg dose group(P<0.05).The boundary between cortex and medulla was blurred,the lymphocytes in cortex and medulla were decreased and arranged loosely,and a small number of lympho-cytes had reduced volume,smaller cytoplasm,and deep nuclear pyknosis.③ Apoptotic cells were observed in the medullary part of the thymus,especially in the boundary between cortex and medulla.The positive rate of TUNEL staining in the 10 µg/kg dose group was significantly higher than that in the control group(P<0.01).④ The distribution of Foxn1 positive cells were primarily observed in the medulla.A small amount of these cells were also present in the cortex and the boundary between the cortex and medulla.Additionally,the mean density(MD)of Foxn1 positive cells in the thymus of each dose group was lower than that of the control group,and decreased significantly in MD was observed in the 100 µg/kg group(P<0.05).⑤ qPCR analysis revealed that the expression level of Foxn1 mRNA in the thymus of the mice injected with different doses of Ghrelin was lower than that of the control group,which was similar to that of immunohistochemistry(P<0.01).In conclusion,injection of different doses of Ghrelin could inhibit the growth of thymus,induce apoptosis of thymus cells and inhibit the expression of Foxn1 gene in African ostrich chicks,which inhibited the normal development of thymus and affect the immunomodulatory capacity of African ostrich chicks.
万方数据
维普
