Which hormone released from the hypothalamus increases when puberty begins?

The hormone that increases when puberty begins is Gonadotropin-releasing hormone (GnRH). This hormone plays a crucial role in the onset of puberty as it stimulates the pituitary gland to release other key hormones such as LH (Luteinizing hormone) and FSH (Follicle-stimulating hormone) that are essential for the development of reproductive functions.

At the start of puberty, the hypothalamus increases the secretion of GnRH in a pulsatile manner, which triggers the anterior pituitary gland to release LH and FSH. These hormones subsequently promote the development of secondary sexual characteristics, gametogenesis, and the overall maturation of the reproductive system. This sequence marks the transition from childhood to reproductive maturity.

The other options, while related to the reproductive hormone pathway, do not initiate the processes of puberty directly. Follicle-stimulating hormone and Luteinizing hormone are released as a response to GnRH, and Estrogen is a hormone produced in greater amounts during puberty but is not released from the hypothalamus itself. Therefore, understanding the role of GnRH highlights its importance as the key trigger for the changes associated with the onset of puberty.