Which of the following is a primary effect of increased gastrin levels in Zollinger-Ellison syndrome?

In Zollinger-Ellison syndrome, there is an inappropriate secretion of gastrin, which significantly elevates the levels of this hormone in the bloodstream. Gastrin is primarily produced by G cells in the gastric mucosa, and its main role is to stimulate the parietal cells of the stomach to produce gastric acid (hydrochloric acid). Therefore, the primary effect of increased gastrin levels is an increase in gastric acid production.

This excessive gastric acid leads to various gastrointestinal complications, such as recurrent peptic ulcers, diarrhea, and abdominal pain, due to the high acidity increasing the potential for mucosal injury. The other possible effects related to gastrointestinal function, such as increased motility, could occur as a secondary response to the changes in gastric acid and other factors, but they are not the primary effect of increased gastrin levels. Understanding this mechanism is crucial in recognizing how gastrin influences gastric physiology in conditions like Zollinger-Ellison syndrome.