Abstract: Objective · To explore the effects of inhibiting thyroid transcription factor 1 (Ttf1) expression on Kiss1 and gonadotropin-releasing hormone (GnRH) expressions in neuronal cells and hypothalamic arcuate nucleus (ARC) of female rats. Methods · Three shRNAs (TTF1-shRNA1, TTF1-shRNA2, and TTF1-shRNA3) interference sequences were designed for rat Ttf1 gene and were constructed into lentiviral vectors. The efficiency of LV-TTF1-shRNA was detected by real-time PCR and Western blotting in neuronal cell line ND7-23. And the expressions of Kiss1 and GnRH were tested 72 h after transfection. Moreover, LV-TTF1-shRNA or the blank lentiviral vector was injected into 21-day female rats’ ARC. Kiss1 and GnRH expressions were detected at the juvenile (25-day), early puberty (35-day) and adult (42-day) stages. Meanwhile, vaginal opening time of the rats was recorded. Results · Seventy-two hours after lentivirus transfection in ND7-23 cells, the mRNA and protein expressions of Ttf1 decreased significantly in LV-TTF1-shRNA2 group and LV-TTF1-shRNA3 group (all P<0.05), particularly in LV-TTF1-shRNA3 group. The expressions of Kiss1 and GnRH mRNA reduced significantly after LV-TTF1-shRNA3 being transfected in ND7-23 cells (both P<0.05). After injection of LV-TTF1-shRNA3 in female rats’ ARC, mRNA abundance of Kiss1 and GnRH showed evident reduction at 25-day, 35-day and 42-day stages (all P<0.05). And KISS1 protein reduced significantly at 35-day and 42-day stages. Female rats transfected with LV-TTF1-shRNA3 showed delayed vaginal opening. Conclusion · Inhibition of Ttf1 gene expression not only significantly reduces the expression of Kiss1 and GnRH in neuronal cells and female rats’ ARC, but also causes female rats vaginal opening delay.

Key words: thyroid transcription factor 1 (TTF1), Kiss1 gene, gonadotropin-releasing hormone (GnRH), RNA interference (RNAi), lentiviral vector, puberty