Autoradiographic demonstration of in vivo 125I-growth hormone-releasing hormone (GHRH) binding by human GH-secreting pituitary adenomas transplanted on athymic nude mice.

ABSTRACT

This study was designed for the purpose of investigating a method for in vivo tumor labelling of human GH (hGH) secreting pituitary adenomas. Pituitary adenoma tissue removed from four acromegalic patients was transplanted into 62 athymic nude mice. After positive GHRH stimulation tests 125I-GHRH(1-44) NH2 was injected intravenously (i.v.) in ten nude mice. 10 min after 125I-GHRH injection, the nude mice were sacrificed, the transplants excised and prepared for light microscopical autoradiography. The mouse pituitary and skeletal muscle specimens served as controls. After the i.v. injection of 125I-GHRH we observed a marked accumulation of silver grains within the adenoma tissue indicating tumor labelling. This study is a first step in investigating a new method for labelling small residues of hGH secreting pituitary adenomas intraoperatively.