open access

Vol 59, No 3 (2008)
Original papers
Published online: 2008-05-08
Submitted: 2013-02-15
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Somatostatin receptors in GH-secreting pituitary adenomas - their relationship to the response to octreotide

Marek Pawlikowski, Hanna Pisarek, Jolanta Kunert-Radek, Maciej Radek
Endokrynologia Polska 2008;59(3):196-199.

open access

Vol 59, No 3 (2008)
Original papers
Published online: 2008-05-08
Submitted: 2013-02-15

Abstract

Twenty pituitary adenomas, surgically removed from patients suffering from acromegaly, were studied. The tumours were immunostained with anti-GH and anti-PRL antibodies and with antibodies raised against particular subtypes of somatostatin receptors (rsst1–5). Expression of rsst immunoreactivity was scored using the following scale: 0 - negative reaction, 1 - weak reaction, 2 - moderate reaction, 3 - strong reaction. In 15 patients in whom the GH response to the acute administration of 200 ug octreotide was tested the correlation between the expression of rsst and the percentage of GH drop was estimated. All the tumours were GH-immunopositive and in the majority (14/20) co-expression of PRL was also found. All the adenomas examined expressed rsst2A (20/20) and rsst5 (12/12) receptor proteins. Receptors sst2B and rsst3 were found in all but one of the tumours examined (19/20 and 11/12, respectively). None of tumours investigated presented rsst4 immunopositivity. The mixed (GH/PRL) adenomas showed a tendency to a higher expression of rsst2A + + rsst2B and a greater response to octreotide administration. A significant positive correlation was found between rsst2A + rsst2B expressions and a drop in GH after octreotide.
To conclude, the GH-inhibiting effect of octreotide depends on the intensity of expression of both rsst2A and rsst2B. Both isoforms of rsst2 mediate the same biological response (inhibition of GH secretion) in GH-secreting and GH/PRL-secreting adenomas.

Abstract

Twenty pituitary adenomas, surgically removed from patients suffering from acromegaly, were studied. The tumours were immunostained with anti-GH and anti-PRL antibodies and with antibodies raised against particular subtypes of somatostatin receptors (rsst1–5). Expression of rsst immunoreactivity was scored using the following scale: 0 - negative reaction, 1 - weak reaction, 2 - moderate reaction, 3 - strong reaction. In 15 patients in whom the GH response to the acute administration of 200 ug octreotide was tested the correlation between the expression of rsst and the percentage of GH drop was estimated. All the tumours were GH-immunopositive and in the majority (14/20) co-expression of PRL was also found. All the adenomas examined expressed rsst2A (20/20) and rsst5 (12/12) receptor proteins. Receptors sst2B and rsst3 were found in all but one of the tumours examined (19/20 and 11/12, respectively). None of tumours investigated presented rsst4 immunopositivity. The mixed (GH/PRL) adenomas showed a tendency to a higher expression of rsst2A + + rsst2B and a greater response to octreotide administration. A significant positive correlation was found between rsst2A + rsst2B expressions and a drop in GH after octreotide.
To conclude, the GH-inhibiting effect of octreotide depends on the intensity of expression of both rsst2A and rsst2B. Both isoforms of rsst2 mediate the same biological response (inhibition of GH secretion) in GH-secreting and GH/PRL-secreting adenomas.
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Keywords

acromegaly; somatostain receptors; octreotide

About this article
Title

Somatostatin receptors in GH-secreting pituitary adenomas - their relationship to the response to octreotide

Journal

Endokrynologia Polska

Issue

Vol 59, No 3 (2008)

Pages

196-199

Published online

2008-05-08

Bibliographic record

Endokrynologia Polska 2008;59(3):196-199.

Keywords

acromegaly
somatostain receptors
octreotide

Authors

Marek Pawlikowski
Hanna Pisarek
Jolanta Kunert-Radek
Maciej Radek

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