Pituitary Tumors Express Growth Hormone Peptide Receptors That Can Release Hormones | Research

The takeaway

Most human pituitary adenomas express functional GH secretagogue receptors regardless of tumor type, with clinical implications for tumor diagnosis and the effects of GH peptide therapy in patients with pituitary tumors.

28 of 30 tumors
Nearly all pituitary adenomas expressed functional GH secretagogue receptors, regardless of tumor type — not just GH-secreting tumors

What the researchers found

GHS-R was expressed in 28 of 30 pituitary adenomas across all subtypes, not just GH-secreting tumors. Functional studies showed GH secretagogues stimulated hormone release from multiple tumor types in culture.

Why it matters

If GH secretagogues can stimulate hormone release from pituitary tumors, this has safety implications for patients using these peptides who may have undiagnosed pituitary adenomas (which are surprisingly common).

How the study worked

In-vitro study of 30 surgically removed human pituitary adenomas (6 GH, 3 GH-PRL, 6 PRL, 5 ACTH, 1 TSH, 4 gonadotroph, 5 non-secreting). RT-PCR for GHS-R mRNA, triple in-situ hybridization for cellular localization, and cell culture for functional hormone release studies.

What this study cannot tell us

In-vitro study on surgically removed tumors, which may not represent the full range of pituitary adenomas. Cell culture responses may differ from in-vivo tumor behavior. Clinical significance of receptor expression was not determined.

How to read the evidence

Preliminary but comprehensive in-vitro evidence from 30 human tumors with both molecular and functional characterization.

When this study was published

Published in 1999. The clinical significance of GHS-R expression in pituitary tumors continues to be studied.

The bigger picture

Pituitary microadenomas are found in up to 20% of the general population at autopsy. If GH secretagogues can activate receptors on these tumors, there are potential safety considerations for widespread GH peptide use.

Questions still open

Could GH secretagogue use stimulate growth of pituitary adenomas?
Should patients be screened for pituitary tumors before GH peptide therapy?
Can GHS-R expression be used as a diagnostic marker for pituitary tumor classification?

Common questions

Are pituitary tumors common?

Small pituitary tumors (microadenomas) are found in up to 20% of people at autopsy, often without causing symptoms. The fact that these tumors express GH secretagogue receptors means GH peptide use could potentially affect them.

Does this mean GH peptides are dangerous for people with pituitary tumors?

Not necessarily, but it's a concern. If GH secretagogues can stimulate hormone release from pituitary tumors, they could worsen conditions like Cushing's disease or prolactinomas. This highlights the importance of medical evaluation before using GH peptides.

Read the original research

Expression of functional growth hormone secretagogue receptors in human pituitary adenomas: polymerase chain reaction, triple in-situ hybridization and cell culture studies.

Journal of neuroendocrinology, 11(7), 491-502

View on PubMed ↗

Citation

Barlier, A; Zamora, A J; Grino, M; Gunz, G; Pellegrini-Bouiller, I; Morange-Ramos, I; Figarella-Branger, D; Dufour, H; Jaquet, P; Enjalbert, A. (1999). Expression of functional growth hormone secretagogue receptors in human pituitary adenomas: polymerase chain reaction, triple in-situ hybridization and cell culture studies.. Journal of neuroendocrinology, 11(7), 491-502.