GHRH regulates growth hormone release from the pituitary and, in addition to this neuroendocrine actions, much evidence implies an additional role for GHRH in carcinogenesis in non-pituitary tissues. Moreover, hypothalamic tumors (as e.g. hamartomas, choristomas, gliomas and gangliocitomas) may produce excessive GHRH. This increased production may lead to subsequent GH hypersecretion, resulting in acromegaly. Immunoreactivity for GHRH is present in several tumors, including carcinoid tumors, pancreatic cell tumors, small-cell lung cancers, adrenal adenomas and pheochromocitomas which have been reported to secrete GHRH.
A potential therapeutic treatment to suppress the effects of GHRH-overex-pression is the use of GHRH antagonists. Moreover, several GHRH antagonists have antiproliferative effects in many tumor models. However, GHRH antagonists that should act within the hypothalamus must cross the blood-brain barrier. Recently, one GHRH antagonist was found to cross the blood-brain barrier, indicating that GHRH antagonists may provide a potential treatment for malignant glioblastomas.
However, to date, no major contribution of GHRH in neurological disorders or neurodegenerative diseases has been documented.
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