| Summary: | 碩士 === 國防醫學院 === 生物及解剖學研究所 === 89 === 英文摘要
The secretion of growth hormone, prolactin and thyrotropin in anterior pituitary gland of spontaneously hypertensive rats (SHR) are higher than in that of age- matched Wista-Kyoto rats (WKY). The expressions of all the three hormones are commonly regulated by pituitary specific transcription factor 1 (Pit-1) and other different factors. The fact that endothelin-1 (ET-1), whose promoter contains a Pit-1 consensus sequence exists in the pituitary gland cells seems to indicate that the ET-1 can also be regulated by Pit-1 transcription factor. Western blot was used in the present study to compare the quantity of Pit-1 nuclear protein in anterior pituitary gland cells of 8 week-old SHR and WKY rats. RT-PCR was used to identify if there was any isoform of Pit-1 mRNA in these rats. The results showed no significant amount of difference between SHR and WKY rats. Two different isoforms of Pit-1 mRNA were detected in both of SHR and WKY rats. It was suggested that the abnormal hormone secretion in anterior pituitary gland cells of SHR is not because of Pit-1 but may be related to other cofactors. The plasmids of ET-1 promoter were constructed by using deletion mutation and then the plasmids were transfected to GH3 pituitary gland cell line. The results demonstrated that once the fragment, 166bps of ET-1 promoter, was deleted, the expression decreased about 4 folds comparing to the full length of ET-1 promoter. The decreasing activity of ET-1 promoter deletion mutant was also found in the anterior pituitary gland cells of SHR and WKY in vitro. The decreasing of the activity in SHR was greater than that in age-matched WKY rats. It was proposed that the different expression of the ET-1 promoter deletion mutant between SHR and WKY may be due to other Pit-1 related cofactors.
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