SERUM GROWTH HORMONE AND ULTRASTRUCTURAL STUDIES OF ADENOHYPOPHYSIAL TISSUE IN BROMOCRIPTINE TREATED ACROMEGALIC PATIENTS

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Abstract
The therapeutic effectiveness of bromocriptine as well as the post-operative ultrastructural aspects of treated pituitary adenomas were investigated in 5 acromegalic patients. Although basal GH [growth hormone] concentrations decreased and the glucose tolerance test and the TSH [thyrotropin] responses were significantly improved, the release of GH induced by TRH [thyroliberin] was not prevented by the dopaminergic agonist. Adenomatous cells were densely granulated and contained a dilated endoplasmic reticulum. Misplaced exocytosis was frequently observed. Bromocriptine apparently inhibits the spontaneous release of GH but does not interfere with the abnormal GH response to TRH. This suggests a separate site of action. The drug seems not to block the synthesizing activity of the adenomatous cell, a finding in accordance with clinical observations that warns against its use as a single therapeutic agent.