ZE paradox

[Ophthoseidon]

Does anyone know why there is a paradoxical increase in gastrin secretion when administering secretin? I understand that when you use secretin, this inhibits gastrin secretion, but obviously the gastrin secreted by the tumor is still there. But why would using secretin actually INCREASE what's already being produced by the gastrinoma?

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[RnaPolymerase2]

It's all about abnormal vs normal G cells.
Secretin inhibit normal G cells function Eg. Achlorhydria cause normal G cell hyperplasia (hypergastrinemia)and ZE abnormal G cells are dysfunctional... So exogenous Secretin will not work well on abnormal G cells. Therefore there's no inhibition and there will be hypergastrinemia.
I hope this helps!!

 

[Jabbed]

 

[Macaroon_Berry]

It's all about abnormal vs normal G cells.
Secretin inhibit normal G cells function Eg. Achlorhydria cause normal G cell hyperplasia (hypergastrinemia)and ZE abnormal G cells are dysfunctional... So exogenous Secretin will not work well on abnormal G cells. Therefore there's no inhibition and there will be hypergastrinemia.
I hope this helps!!

I believe the poster is clear on what you had posted, meaning we get that Secretin doesn't work well on abnormal G cells, and thus would not be able to decrease G cell secretion because they're hyperplastic. But secretin also causes a paradoxical INCREASE in G cell secretion in gastrinoma (a quick google search proves that's the case as well), and the poster was asking why that happened.

 

[plasmodium]

Perhaps secretin-induced alkalization of the luminal contents results in gastrin secretion from the G cells in the gastric antrum and duodenum that is additive to the gastrin released from the gastrinoma (depending on the location of the primary tumor).

 

[Transposony]

That's because gastrinoma cells have secretin receptors and secretin stimulation causes these cells to release stored gastrin.
In other words, secretin does not stimulate normal antral G cells to release gastrin but it stimulates gastrinoma cells to release gastrin.
Hence the paradox.

 

[plasmodium]

That's because gastrinoma cells have secretin receptors and secretin stimulation causes these cells to release stored gastrin.
In other words, secretin does not stimulate normal antral G cells to release gastrin but it stimulates gastrinoma cells to release gastrin.
Hence the paradox.

Interesting, thanks. Do you by any chance have the source for this information?

 

[Transposony]

Interesting, thanks. Do you by any chance have the source for this information?

http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2036.2009.03976.x/pdf