Injection of which of the following increases metabolic rate?

Options

A. STH
B. Insulin
C. Thyroxine
D. Testosterone

Answer

To determine which hormone injection increases metabolic rate, we can analyze the given options one by one:

1. **STH (Somatotropin or Growth Hormone)**:
- This hormone is primarily responsible for growth and development in animals.
- It does not have a direct role in increasing metabolic rate.
- **Conclusion**: STH does not increase metabolic rate.

2. **Insulin**:
- Insulin is produced by the pancreas and primarily functions to lower blood glucose levels by facilitating the uptake of glucose into cells.
- Its main role is in glucose metabolism rather than directly increasing metabolic rate.
- **Conclusion**: Insulin does not increase metabolic rate.

3. **Thyroxine**:
- Thyroxine is a hormone produced by the thyroid gland.
- It plays a crucial role in regulating the body's metabolic rate.
- An increase in thyroxine levels leads to an increase in the metabolic rate, as it stimulates various metabolic processes in the body.
- **Conclusion**: Thyroxine increases metabolic rate.

4. **Testosterone**:
- Testosterone is the primary male sex hormone produced in the testes.
- While it has various functions related to male reproductive health and muscle mass, it does not primarily regulate metabolic rate.
- **Conclusion**: Testosterone does not increase metabolic rate.

Based on the analysis of all options, the hormone that increases metabolic rate is **Thyroxine**.