## **Core Concept**
Ghrelin is a peptide hormone produced in the gastrointestinal tract and functions as a neuropeptide in the central nervous system. It plays a significant role in regulating appetite and energy balance. One of its key actions is to stimulate the secretion of a specific hormone from the anterior pituitary gland.

## **Why the Correct Answer is Right**
Ghrelin is known to stimulate the release of **growth hormone (GH)** from the anterior pituitary gland. This action is mediated through ghrelin's ability to bind to growth hormone secretagogue receptors (GHS-R) in the pituitary gland, leading to an increase in GH secretion. GH has various effects, including stimulating growth, cell reproduction, and cell regeneration in humans and other animals.

## **Why Each Wrong Option is Incorrect**
- **Option A:** While ghrelin does have effects on the gastrointestinal system, its primary action related to the question is not the release of gastrin, which is more directly involved in stimulating gastric acid secretion.
- **Option B:** Insulin is involved in glucose regulation and is not directly stimulated by ghrelin. In fact, ghrelin can have effects that are opposite to insulin, such as increasing glucose levels by reducing insulin sensitivity.
- **Option C:** Glucagon-like peptide-1 (GLP-1) is involved in glucose metabolism and is not directly stimulated by ghrelin. GLP-1 and ghrelin have somewhat opposing effects on appetite and glucose metabolism.

## **Clinical Pearl / High-Yield Fact**
A key clinical pearl is that ghrelin levels typically rise before meals to stimulate appetite and decrease after meals. This hormone has been a focus of research for its potential role in regulating appetite and body weight, making it a significant target for studying obesity and metabolic disorders.

## **Correct Answer:** D. Growth hormone.