Which of the following is a paracrine hormone?

Options

A. Insulin
B. Glucagon
C. Somatostatin of pancreas
D. GH (Growth hormone)

Answer

To determine which of the following is a paracrine hormone among the options provided (insulin, glucagon, somatostatin, and growth hormone), we need to understand the definition of paracrine hormones and analyze each option accordingly.

### Step-by-Step Solution:

1. **Understanding Paracrine Hormones**:
- Paracrine hormones are signaling molecules that act on nearby cells rather than traveling long distances to affect distant organs or tissues. They exert their effects locally.

2. **Analyzing Insulin**:
- Insulin is secreted by the pancreas and primarily acts on the liver to regulate glucose metabolism. Since the liver is not adjacent to the pancreas, insulin does not qualify as a paracrine hormone.

3. **Analyzing Glucagon**:
- Glucagon is also secreted by the pancreas and primarily affects the liver, similar to insulin. Since it also acts on a distant organ (the liver), glucagon is not a paracrine hormone.

4. **Analyzing Somatostatin**:
- Somatostatin, also known as growth hormone-inhibiting hormone (GHIH), is secreted by the delta cells of the pancreas. It acts on nearby cells in the stomach to inhibit the secretion of gastrin and stomach acids. Since it functions on neighboring cells, somatostatin qualifies as a paracrine hormone.

5. **Analyzing Growth Hormone (GH)**:
- Growth hormone affects a wide range of cells throughout the body, including both nearby and distant cells. Therefore, it does not fit the definition of a paracrine hormone.

6. **Conclusion**:
- Among the options given, somatostatin is the only hormone that acts on nearby cells, making it the correct answer.

### Final Answer:
The paracrine hormone among the options is **somatostatin**.

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