Tumor Secretions

[seminoma]

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So dexamethasone won't suppress ectopic ACTH, but octreotide will suppress appendiceal serotonin secretion (as in a carcinoid tumor).

Why is this inconsistent? I get that the SCLC cells probably don't have cortisol receptors and/or appropriate feedback mechanisms and hence are resistant to negative feedback, but I would guess that the appendix doesn't have appropriate mechanisms for somatostatin signaling since it doesn't usually do anything with somatostatin.

 

[aspiringmd1015]

i guess that would maybe mean that all tissues in your body have somostatatin receptors

 

[Transposony]

Octreotide inhibits secretion of serotonin and other GI peptide hormones like gastrin, VIP, insulin, secretin, etc.
Serotonin is secreted throughout GI tract and Carcinoid being a benign tumor is likely to be more susceptible to the charms of octreotide (more likely to have normal/working receptors).