Responsiveness of irradiated rat anterior pituitary cells to hypothalamic releasing hormones is restored by treatment with growth hormone

Hypopituitarism is a common sequela of irradiation in cancer patients. Here we report that recombinant human growth hormone (r-hGH) prevents cell deat h and restores secretory capacity of irradiated rat pituitary cells in vitr o. Dispersed rat pituitary cells from male Sprague-Dawley rats, irradiated with a 9-Gy sublethal dose, were incubated with r-hGH before, after, or bef ore and after irradiation. Treatment with GH resulted in increased cell sur vival, which reached its maximum at the concentration of 5 nM, with an EC50 of 3.5 nM. Protective effects of GH on pituitary cells were more pronounce d in cultures treated before and after irradiation. Similarly, beneficial e ffects of GH were observed on the secretory capacity of surviving cells, In fact, irradiated pituitary cells treated with GH secreted substantial amou nts of GH, luteinizing hormone, follicle-stimulating hormone, prolactin, th yroid-stimulating hormone and adrenocorticotropic hormene in response to sp ecific releasing hormones. Such effects of GH were prevented in the presenc e of the specific GH receptor antagonists B2036 and G120K. Our results show th at r-hGH exerts a specific protective effect on irradiated rat pituitar y cells and suggest possible use of GH as an adjuvant agent for prevention of postirradiation hypopituitarism, Copyright (C) 2000 S. Karger AG, Basel.