Which of the following statement is not correct regarding epinephrine and nor-epinephrine ?

Options

A. Both act like as neurotransmitter
B. Their receptors are present on post - synaptic membrane
C. They are antagonistic neurotransmitter
D. Both are catecholamines

Answer

To determine which statement is not correct regarding epinephrine and norepinephrine, we will analyze the provided statements step by step.

### Step-by-Step Solution:

1. **Understanding the Hormones**:
- Epinephrine (also known as adrenaline) and norepinephrine are hormones produced by the adrenal medulla.
- Both are classified as catecholamines.

2. **Functions of Epinephrine and Norepinephrine**:
- Both hormones are involved in the body's response to stress, often referred to as the "fight or flight" response.
- They have similar physiological effects, such as increasing heart rate, blood pressure, and blood glucose levels.

3. **Analyzing the Statements**:
- **Statement 1**: Both act as neurotransmitters.
- This statement is correct. Both epinephrine and norepinephrine can function as neurotransmitters in the nervous system.

- **Statement 2**: Their receptors are present at the postsynaptic membrane.
- This statement is also correct. The receptors for these hormones are located on the postsynaptic membrane of target cells.

- **Statement 3**: They are antagonistic neurotransmitters.
- This statement is incorrect. While they have different conditions under which they are released (epinephrine during emergencies and norepinephrine during non-emergencies), their actions are not antagonistic; they generally have similar effects on the body.

- **Statement 4**: They are catecholamines.
- This statement is correct. Both hormones are classified as catecholamines.

4. **Conclusion**:
- The statement that is not correct regarding epinephrine and norepinephrine is that they are antagonistic neurotransmitters. Therefore, the answer is option number 3.

### Final Answer:
The statement that is not correct regarding epinephrine and norepinephrine is: **They are antagonistic neurotransmitters.**

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