Which of these hormones uses cAMP as a second messenger ?

Options

A. Estrogen
B. Cortisol
C. Epinephrine
D. Testosterone

Answer

To determine which hormone uses cAMP (cyclic adenosine monophosphate) as a second messenger, we need to analyze the types of hormones listed in the question. Here’s a step-by-step breakdown of the solution:

### Step 1: Identify the Hormones
The hormones given in the question are:
1. Estrogen
2. Cortisol
3. Epinephrine
4. Testosterone

### Step 2: Classify the Hormones
Next, we classify these hormones into their respective categories:
- **Estrogen**: This is a steroid hormone.
- **Cortisol**: This is also a steroid hormone.
- **Epinephrine**: This is an amino acid derivative hormone.
- **Testosterone**: This is another steroid hormone.

### Step 3: Understand the Mechanism of Action
Hormones can be classified based on their mechanism of action:
- **Steroid Hormones**: These hormones are lipophilic and can pass through cell membranes. They typically act directly on the DNA in the nucleus to regulate gene expression and do not use second messengers like cAMP.
- **Protein Hormones and Amino Acid Derivative Hormones**: These hormones are hydrophilic and cannot pass through the cell membrane. They rely on second messengers to exert their effects inside the cell. cAMP is one of the most common second messengers used by these hormones.

### Step 4: Identify the Correct Hormone
From the classification:
- Estrogen, cortisol, and testosterone are steroid hormones and do not use cAMP as a second messenger.
- Epinephrine, being an amino acid derivative hormone, does use cAMP as a second messenger.

### Conclusion
Thus, the hormone that uses cAMP as a second messenger is **Epinephrine**.

### Final Answer
The correct answer is **Epinephrine**.

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