二氢睾酮诱导小鼠雄激素性脱毛的机制研究

Mechanism of androgenetic alopecia in mouse model

目的通过建立二氢睾酮(DHT)诱导的雄激素性脱毛(AGA)小鼠模型,研究DHT导致AGA发生、发展的相关分子机制。方法采用DHT浓度梯度法对112只正常适龄雌性小鼠进行皮下给药,并通过人工脱毛使小鼠毛发生长周期同步化。通过HE染色观察DHT处理后不同时期小鼠毛囊形态结构及毛囊数目的改变,以确定AGA小鼠模型的建立。采用RT-PCR法对影响不同时期毛囊循环再生的相关信号分子的m RNA表达水平进行分析并比较。结果不同浓度DHT处理后的小鼠在毛发生长不同阶段均表现出典型的毛囊小型化和毛发稀疏。在整个毛发生长周期中雄激素受体(AR)的m RNA表达水平几乎都呈上升趋势,而在第40、48天呈下降趋势。通过对毛囊干细胞表面标志物的m RNA表达水平分析发现,富含亮氨酸重复序列的G蛋白偶联受体5(Lgr5)的m RNA表达水平在毛发生长期-休止期VI期之间呈下降趋势,而CD34的m RNA表达水平无明显变化。外源性增加DHT剂量,细胞内AR的m RNA表达水平也相应增加,促毛发生长因子如成纤维细胞生长因子受体(FGFR)、人胰岛素样生长因子结合蛋白-5(IGF-BP5)、Ptch1及Wnt信号相关蛋白的m RNA表达水平降低。结论 DHT处理后可成功诱导AGA小鼠模型。DHT能够活化真皮乳头细胞中的AR受体,与毛囊上皮细胞相互作用,对促毛发生长因子FGFR、IGF-BP5、Ptch1及Wnt信号相关蛋白的表达产生抑制作用。

Objective To explore the mechanism of androgenetic alopecia （AGA） in mouse model. Methods AGA model was induced by subcutaneous injection of dehydrotestosterone （DHT） with concentration gradient method in 112 female mice. Hair depilation method was used to synchronize the initial stage of hair growth cycle of injected mice. The morphology and number of follicle were observed by H.E staining, and the mRNA expressions of signaling molecules in hair follicles were detected by RT-PCR. Results The follicular miniaturization and hair thinning were observed in mice treated with different concentration of DHT throughout the hair cycle. RT-PCR results showed the expression of androgen receptor （AR） was increased in whole hair cycle, but decreased at d40 and d48. The mRNA expression of stem cell marker Leucine-rich repeat-containing G-protein coupled receptor 5 （Lgr5） was decreased during telogen and anagen Vl phases, while the expression of CD34 had no significant changes. The expressions of FGFR, IGF-BP5, Ptchl and Wnt were reduced compared with control group. Coinciding with decreased AR expression at d40 and d48, the levels of PDGFRα were significantly declined （P〈0.05）. The expression of basement membrane components laminin α 3 was up-regulated, and laminin α5 was down-regulated in DHT-induced AGA mouse. Conclusion DHT can stably induce androgenetic alopecia in mice. DHT can inhibit the expression of hair growth factor FGFR, IGF-BP5, Ptchl and Wnt signaling by activating the AR in DP cells and interacting with epithelial cells in the hair follicle.