OCTREOTIDE TREATMENT RESULTS IN THE INHIBITION OF GH GENE-EXPRESSION IN THE ADENOMA OF THE PATIENTS WITH ACROMEGALY

Seven patients with growth hormone (GH)-secreting pituitary adenoma we re treated preoperatively with octreotide (Sandostatin or SMS 201-995; a somatostatin analogue), and were compared with 18 non-treated patie nts in their clinical courses and adenoma analyses. Octreotide treatme nt improved the endocrinological data in all 7 cases. The octreotide-t reated adenomas were soft and easily removed by suction and curettage, The postoperative normalization of endocrinological data was encounte red more often in the octreotide-treated cases than in the non-treated , although the statistical significance was not observed by the limite d number of cases. The adenoma tissues were examined with conventional histology and immunohistochemistry, and the amount of GH messenger ri bonucleic acid (mRNA) was quantitatively assessed. The studies demonst rated: 1) No fibrosis nor necrosis was observed in the adenomas from t he octreotide-treated patients. 2) Immunohistochemistry for human GH r evealed no remarkable differences between the octreotide-treated and t he non-treated adenomas. 3) The amounts of GH mRNA in the adenoma from the octreotide-treated patients were 4.2 +/- 1.8 (mean +/- SEM; expre ssed in an arbitrary unit) and were significantly less than those from the non-treated (33.6 +/- 9.1). These data suggest that octreotide in hibits not only GH release from the adenoma but also its biosynthesis.