THE LEVELS AND SUBCELLULAR DISTRIBUTION OF HORMONES AND MARKER ENZYMES IN PITUITARIES FROM CONTROL SUBJECTS AND PATIENTS WITH PROLACTINOMAS, ACROMEGALY OR FUNCTIONLESS PITUITARY TUMOURS

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Abstract
Pituitary homogenates were prepared from patients undergoing pituitary ablation for breast or prostatic carcinoma (controls) and from patients with either PRL- and GH-secreting pituitary adenomas or from patients with 'functionless' pituitary tumours. The principal subcellular organelles, plasma membrane, lysosomes, mitochondria, endoplasmic reticulum, cytosol and hormone-containing granules were characterized by sucrose density gradient centrifugation. Tissue from patients with prolactinomas showed hormone granules, lysosomes and endoplasmic reticulum of lighter density than controls; cytosol, mitochondria and plasma membrane were similar. PRL-secreting tumours showed a 2-fold increase in PRL content with significant reduction of LH, FSH and GH. Activities of various lysosomal enzymes, except for PRL proteolytic activity, were significantly reduced. Similar conclusions were found for GH-secreting pituitary adenomas with a striking reduction in PRL proteolytic activity. Functionless tumours showed significant amounts, though reduced compared to control tissue, of all hormones. In contrast to the hormone-secreting adenomas, the activity of the lysosomal enzyme N-acetyl-beta-glucosaminidase was significantly increased compared to control tissue.

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