Changes in GnRH pulse frequency in females is controlled by circulating levels of

Options

A. Estrogen and inhibin
B. Progesterone only
C. progesterone and inhibin
D. Estrogen and progesterone

Answer

### Step-by-Step Solution:

1. **Understanding GnRH**: Gonadotropin-Releasing Hormone (GnRH) is a hormone secreted by the hypothalamus that plays a crucial role in regulating the female reproductive system.

2. **GnRH Function**: GnRH stimulates the anterior pituitary gland to release two key hormones: Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH). These hormones are essential for the functioning of the ovaries.

3. **Ovarian Response**: FSH and LH act on the ovaries, leading to the production of sex hormones, primarily estrogen and progesterone.

4. **Feedback Mechanism**: The levels of estrogen and progesterone in the bloodstream provide feedback to the hypothalamus and pituitary gland:
- **Negative Feedback**: When the levels of estrogen and progesterone are high, they inhibit the release of GnRH, FSH, and LH, reducing their levels.
- **Positive Feedback**: Conversely, when the levels of estrogen and progesterone are low, this stimulates the release of GnRH, leading to an increase in FSH and LH levels.

5. **Conclusion**: The changes in the frequency of GnRH pulses in females are primarily controlled by the circulating levels of estrogen and progesterone. Therefore, the correct answer to the question is that the changes in GnRH pulse frequency are controlled by these hormones.

### Final Answer:
The changes in GnRH pulse frequency in females are controlled by circulating levels of **estrogen and progesterone**.

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