Expression of TTF1 in hypothalamus of female rats and its relationship with GnRH and KiSS1 / 上海交通大学学报（医学版）

ABSTRACT

Objective • To investigate the changes and distribution of thyroid transcription factor-1 (TTF1) expression around the puberty and to explore the position relationship among gonadotropin-releasing hormone (GnRH), KiSS1 and TTF1 expression in the hypothalamus of female SD rats. Methods • Female SD rats were divided into three groups juvenile (JUV), early puberty (EP), and adult (AD). Tissue immunofluorescence staining was used to detect the expression of TTF1, KiSS1 and GnRH immunoreactive cells in the hypothalamus and the relative position among them. Real-time PCR was used to measure the expression of KiSS1, GnRH, TTF1 on mRNA levels in the hypothalamus, anteroventral periventricular nucleus (AVPV), and arcuate nucleus (ARC) respectively. Western blotting was performed to detect the changes in protein level of KiSS1 and TTF1. Results • TTF1 was densely expressed in hypothalamus nucleus AVPV, ARC and median eminence (ME) of female rats. GnRH,KiSS1 and TTF1 were adjacently expressed in ARC and ME. The mRNA level of TTF1 in the hypothalamus showed an upward trend after a slight decrease, while in AVPV and ARC tended to be consistent and showed an upward trend. The GnRH mRNA expression levels were significantly increased and reached the peak at AD. The mRNA expression levels of KiSS1 showed a sharp rise which was prior to the peak expression of GnRH mRNA at EP and then sustained the high level until AD. The protein expression level of TTF1 reached the peak at AD and the KiSS1 expression showed a sustained growth. Both of them showed an upward trend and basically consistent with the mRNA expression trend. Conclusion • Neuronal nuclei protein TTF1 mainly expressed in the nuclei AVPV, ARC, and ME of female rat hypothalamus. It was prominent in cells of ARC and ME which were localized GnRH, KiSS1, TTF1 positive neural cells. During the development of puberty onset, KiSS1 mRNA preceded GnRH mRNA to reach the peak at EP. The expression of TTF1 mRNA increased and reached a peak at AD, which was consistent with the overall increase of KiSS1 and GnRH expression. Protein expression of KiSS1 showed a corresponding upward trend together with their mRNA expression. TTF1 protein expression increased and peaked in AD.