Hormone secretion on several stages of tumorgenesity and growth rates of pituitary adenomas

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1. We studied prolactin (PRL) release from individual pituitary cells in normal and estrogen (E2) -treated female Fisher 344 rats by means of reverse hemolytic plaque assay. Multimodal distribution of PRL secretion was observed in normal pituitary cells. On the contrary, bimodal distribution was found in E2-treated pituitary cells. The heterogeneity of the PRL secretion from a single pituitary cell decreased in association with the length of E2 treatment. The PRL secretion of the E2-treated pituitary cells was less than that of the normal pituitary cells.2. Growth hormone-releasing hormone (GHRH) secreted by monodispersed human GH-producing pituitary adenoma cells was detected by the cell immunoblot assay. It is suggested that autocrinologic growth and/or local regulation of GH secretion by GHRH in human GH-producing pituitary adenomas.3. We examined an antitumoral effect of Cabergolinc (CG) , a dopamine agonist, with comparison to bromocriptine (BC) on E2-induced rat pituitary tumors … More In vitro and In vivo. The result suggests that CG has a higher affinity for the D2 receptor of pituitary cells and antitumor effect at a lower dosage than BC.4. On growth rates of human pituitary adenomas, we examined endocrinologic function, cavernous sinus invasion, and growth rates examined by using anti-proliferating cell nuclear antigen (PCNA) and MIB1 (a novel anti-Ki-67) as markers. The result suggest that endocrinologic function, cavernous sinus invasion, and growth rates are independent biologic behaviors each other.5. As a novel finding, on cavernous sinus invasion, we found that invasive adenomas had higher type IV collagenolytic activity than noninvasive adenomas. Thus, it is suggested that type IV collagenase activity in a pituitary adenoma may be related to its ability to invade the cavernous sinus invasion.6. Further examinations are needed on this points. However, we have already been started to examin matrix metalloproteinase-9, a type IV collagenase, secreted by human pituitary adenomas by means of the cell immunoblot assay. Less