Which hormone is primarily responsible for the suppression of the hypothalamic-pituitary-gonadal (HPG) axis in cases of increased prolactin?

The hormone that primarily suppresses the hypothalamic-pituitary-gonadal (HPG) axis in the context of increased prolactin levels is LHRH, also known as luteinizing hormone-releasing hormone. Increased levels of prolactin can lead to decreased stimulation of gonadotropin-releasing hormone (GnRH), which in turn affects the release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) from the pituitary gland.

When prolactin levels are elevated, it can inhibit the pulsatile release of GnRH from the hypothalamus. This inhibition is significant because GnRH is crucial for stimulating the release of both LH and FSH, which are key hormones in regulating reproductive function.

LHRH's role in the HPG axis specifically involves initiating the release of LH and FSH necessary for gonadal function. Therefore, high levels of prolactin indirectly suppress the signaling that would normally enhance the activity of LHRH, further contributing to decreased gonadal hormone production and function.

In the context of the other choices, while estrogen does play a role in the feedback mechanism of the HPG axis, it is not primarily responsible for the suppression related to elevated prol