Studies on the Expression and the Regulation of Activin in Human Pituitary and Pituitary Adenoma Tissues.

点击翻译按钮获取中文摘要

Activins have been known to modulate various pituitary hormone secretion. To study the localization and the regulation of activins in human pituitary, we studied the expression of inhibin alpha, beta_A, beta_B subunit mRNAs and activin type II receptor mRNA in various human pituitary tissues. We found that inhibin alpha and beta_A subunits and activin type II receptor mRNAs were expressed, with the ubiquitous presence of beta_A subunit mRNA in all human pituitary adenoma tissues, regardless of their hormone production. We further measured individual mRNA levels by a quantitative RT-PCR.The inhibin alpha subunit mRNA levels were undetectably low in all 9 cultured adenoma tissues, but beta_A mRNA levels were 0.3830<plus-minus>0.071 in 3 GH adenomas, 0.672<plus-minus>0.140 in 3 prolactinomas and 0.957<plus-minus>0.414 molecules/cell in 3 non-functioning adenomas.The addition of 10^<-8>M activin A decreased the beta_A mRNA level within 4 hours in 5 out of 9 adenomas, though the decreases were not statistically significant. Furthermore, activinimmunoreactivities were demonstrated in the cytoplasm of some of the adenomas, while inhibin alpha subunit immunoreactivity was negative in all of the tissues studied. The data demonstrated a local synthesis of activin in pituitary adenoma tissues in preference to inhibin and its local role in human pituitary adenoma tissues.