Effects Of Androgens On Skin Morphology And Factors Related To Growth And Development Of Pilosebaceous Unit In Hetian Sheep

[Background] Androgens are mainly involved in the development of sexual organs and the regulation of body metabolism through the hypothalamic-pituitary-gonadal axis.Androgen stimulation can promote sebaceous gland proliferation,differentiation and sebum secretion,but the underlying cellular and molecular mechanisms are not fully understood.At present,there is no research on the effect and mechanism of androgen on the sheep follicle and sebaceous gland structure.[Objective] Hetian sheep was used as an animal model in this study to explore the effect of androgens on sheep skin tissue morphology and the mechanism of androgen regulating the growth and development of pilosebaceous gland units.[Method] Hetian sheep were treated with different concentrations of androgens for 42 days,and skin samples were collected from each experimental sheep.Skin tissue sections were prepared,and the effects of androgen on the skin morphology of Hetian sheep were investigated by H&E staining,Sacpic staining,Masson's trichrome staining and Oil red O staining.The distribution of androgen receptor in Hetian sheep skin by IHC and IF technology.Transcriptome sequencing was performed on the skin of each experimental sheep,and the potential mechanisms of androgens on the skin of Hetian sheep were explored through RNA-seq and WGCNA analysis and identifying the key genes and signaling pathways that androgen affected the structure of hair follicles and sebaceous glands.The key genes(ACSL1,KRT79,CERS4)of skin that affect sebum secretion and are regulated by androgen were verified by q RT-PCR,Western Blot,IHC and IF.Finally,the primary culture of Hetian sheep dermal papilla cells was performed to detect the effect of androgen stimulation on the proliferation of dermal papilla cells,and the effect of androgen on the expression of TGF-?/Smad pathway-related genes was detected by q RT-PCR.[Results] Morphological observation showed that the sebaceous glands of Hetian sheep were connected with the primary hair follicles,and the two together constituted the pilosebaceous unit.It was found that androgen stimulation can significantly increase the area of sebaceous glands and promote the regeneration of sebaceous glands in Hetian sheep.Further studies found that androgen stimulation promoted the proliferation and differentiation of sebaceous progenitor cells,but no effect on hair follicle morphology and number of androgens was found.Transcriptomic sequencing data analysis revealed that androgen stimulation may have inhibitory effects on fibrous deposition in sheep skin,and be beneficial in preventing skin fibrosis,increasing ceramide production capacity,improving skin barrier function.Androgens can promote the expression of genes related to skin lipid synthesis and catabolism,have inhibitory effects on the expression of wool fibrin and hair follicle keratin genes,also have inhibitory effects on MAPK,JAK-STAT,GNRH,VEGF,Wnt,Hedgehog and other signaling pathways.The PPAR signaling pathway may be the most important pathway for androgens to promote sebocyte proliferation,differentiation and sebum secretion,the key gene PPARG plays a crucial role in this process.Further research found that androgen stimulation significantly promoted the expression of ACSL1,KRT79,and CERS4 genes and proteins in Hetian sheep skin.With the increase of androgen treatment concentration,the positive expression area of ACSL1,KRT79,and CERS4 proteins increased with the increase of sebaceous gland area.Finally,Hetian sheep dermal papilla cells were successfully cultured,the culture conditions of dermal papilla cells in vitro were established.It was found that androgen treatment can promote the proliferation of dermal papilla cells,significantly down-regulate the expression of TGF-?1,TGF-?RII,Smad2 and Smad6 genes,significantly up-regulate the expression of Smad5 gene.[Conclusion] Androgen stimulation increases the area of sebaceous glands in Hetian sheep,and form the new sebaceous glands.Androgen stimulation promotes the proliferation and differentiation of sebaceous gland progenitor cells,accelerates the produciton,decomposition and metabolism of lipids in the skin.Androgen stimulation promotes the expression of genes related to sebocyte proliferation and differentiation,inhibits the expression of wool fiber structural protein genes.The dermal papilla cells of Hetian sheep were successfully cultured,it was found that androgen stimulation inhibited the expression of TGF-?/Smad pathway genes in cells.This study will provide a theoretical basis for revealing the effect and mechanism of androgens on the structure of hair follicles and sebaceous glands in sheep skin,provide valuable information for in-depth understanding of the molecular and cellular mechanisms of human androgenetic alopecia.