Which of the following neurotransmitter plays a significant role in mood changes.

Options

A. Acetylcholine
B. Dopamine
C. Serotonin
D. Noradrenaline

Answer

**Step-by-Step Solution:**

1. **Understanding Neurotransmitters:**
- Neurotransmitters are chemical messengers that transmit signals in the nervous system. They play a crucial role in communication between neurons and also between neurons and muscles.

2. **Identifying the Neurotransmitters:**
- The question lists several neurotransmitters: Acetylcholine, Dopamine, Serotonin, and Noradrenaline.

3. **Analyzing Each Neurotransmitter:**
- **Acetylcholine:**
- Function: Contracts smooth muscles, dilates blood vessels, increases secretion, and slows down heart rate.
- Role in Mood: No significant role in mood changes.

- **Dopamine:**
- Function: Acts as a neurotransmitter and hormone, involved in sending messages in the nervous system.
- Role in Mood: While it is important for several functions, it does not primarily regulate mood changes.

- **Serotonin:**
- Function: Involved in various functions including the regulation of mood, sleep, and appetite.
- Role in Mood: Although it has some influence on mood, it is not the primary neurotransmitter responsible for mood changes.

- **Noradrenaline (Norepinephrine):**
- Function: Acts as a neurotransmitter and hormone, involved in the body's response to stress and plays a role in attention and responding actions.
- Role in Mood: It is significantly involved in regulating mood and emotional responses.

4. **Conclusion:**
- Based on the analysis, the neurotransmitter that plays a significant role in mood changes is **Noradrenaline**.

5. **Final Answer:**
- The correct answer is **Noradrenaline** (Option D).

---