Cytocidal effects of bromocriptine, somatostatin analog, and heat on growth hormone-secreting pituitary adenomain vitro

Octreotide is a potent agonist of somatostatin that lowers the serum level of growth hormone (GH), and reduces the size of somatotropinomas. However, the detailed mechanism of shrinkage of this tumour is not known. We, therefore, evaluated 11 patients with somatotropinomas who were treated with octreotide 300 micrograms/day for 2-5 weeks to observe the morphological changes in the tumour using electron microscopy and the immunocytochemical study of apoptosis using polyclonal anti-single stranded DNA. Findings were compared with those obtained with bromocriptine treatment (10 mg/day, 2 weeks) of 5 patients with somatotropinomas, and 11 patients who received no preoperative treatment (control group). The octreotide group showed neither increase in stromal tissue nor cell death. The size of tumour cells appeared to be slightly reduced. No typical apoptotic bodies were seen on the electron micrographs. The apoptotic index in the octreotide group (0.40 +/- 0.60%; mean +/- SD) resembled that in the control group (0.81 +/- 0.79%). In contrast, the bromocriptine group showed some cell death and an increase in stromal tissue. The bromocriptine group also showed the apoptotic index which (20.1 +/- 14.8%) was significantly higher than that of the control group (0.81 +/- 0.79%). Thus, octreotide did not induce apoptosis in somatotropinomas despite the presence of tumour shrinkage. Because of the lack of fibrosis observed in the octreotide-treated tumours, the preoperative administration of octreotide may help to improve the outcome of the transsphenoidal operation.

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Absence of apoptosis in somatotropinomas treated with octreotide

Saitoh

Arita

Ohnishi

et al. 1997

Acta neurochir

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Expression of vascular endothelial growth factor in growth hormone-secreting pituitary adenomas: special reference to the octreotide treatment

Kurosaki

Saegert

Abe

et al. 2008

Neurological Research

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Octreotide May Act as A Radioprotective Agent in Acromegaly

Landolt

Haller

Lomax

et al. 2000

The Journal of Clinical Endocrinology &Amp; Metabolism

155

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Clinical experience shows that an increasing number of patients undergoing radiation treatment for recurring acromegaly or acromegaly persisting after surgery are treated with octreotide. We, therefore, performed a follow-up study of patients undergoing stereotactic radiosurgery (Gamma Knife) to determine whether this medication has an influence on the ultimate result of radiation therapy in either a positive or negative sense. It has been suggested that the combination of radiation with antisecretory drugs may increase the effectiveness of radiation. A follow-up study of 31 patients suffering from recurrent acromegaly and acromegaly persisting after surgery, and who had been treated with stereotactic radiosurgery, showed that patients treated with octreotide at the time of radiation application simultaneously reached a normal level of growth hormone and insulin-like growth factor-I only after a significantly longer interval than patients who did not receive the drug. The two groups of patients did not demonstrate significant differences in the main clinical findings (age, sex, target volume, radiation dose, baseline growth hormone, and baseline insulin-like growth factor-I).

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Cytocidal effects of bromocriptine, somatostatin analog, and heat on growth hormone-secreting pituitary adenomain vitro

Cited by 7 publications

References 35 publications

Absence of apoptosis in somatotropinomas treated with octreotide

Absence of apoptosis in somatotropinomas treated with octreotide

Expression of vascular endothelial growth factor in growth hormone-secreting pituitary adenomas: special reference to the octreotide treatment

Octreotide May Act as A Radioprotective Agent in Acromegaly

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