Hypercalcemia in rats bearing growth hormone- and prolactin-secreting transplantable pituitary tumors.
We evaluated the effects of chronic massive elevations of serum GH and PRL on calcium metabolism in rats bearing the MStT/W15 and 7315a transplantable pituitary tumors. MStT/W15 tumor rats manifest elevated serum GH and PRL levels, hypercalcemia, hypercalciuria, and elevated serum levels of PTH and 1,25-dihydroxyvitamin D. The hypercalcemia was not reversed by dexamethasone or propranolol treatment, but was ameliorated by starvation. Parathyroidectomy produced hypocalcemia in the MStT/W15 tumor rats, confirming the parathyroid dependence of the hypercalcemia. The 7315a tumor produced a milder degree of hypercalcemia, along with elevated serum levels of PRL, ACTH, and corticosterone; serum GH was normal. In high concentrations, PRL and/or GH may stimulate the secretion of PTH as well as enhance dietary calcium absorption, in part through the mediation of 1,25-dihydroxyvitamin D.
D000818:Animals; D003404:Creatinine / Q000097:blood; D003907:Dexamethasone / Q000494:pharmacology; D005260:Female; D013006:Growth Hormone / Q000378:metabolism*; D006934:Hypercalcemia / Q000150:complications*; D008274:Magnesium / Q000097:blood; D009368:Neoplasm Transplantation; D010280:Parathyroid Glands / Q000502:physiology; D010911:Pituitary Neoplasms / Q000150:complications* / Q000378:metabolism; D011388:Prolactin / Q000378:metabolism*; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D011920:Rats, Inbred WF; D012709:Serum Albumin / Q000032:analysis; D013217:Starvation / Q000378:metabolism; D013997:Time Factors
D012709:Serum Albumin; D003907:Dexamethasone; D011388:Prolactin; D013006:Growth Hormone; D011433:Propranolol; D003404:Creatinine; D008274:Magnesium