Reproduction - Puberty & Maturity

Question 1

What is the role of leptin in the onset of puberty?

Answer 1

Leptin receptors have been identified in the hypothalamus, gonadotrope cells of the anterior pituitary, and ovarian follicular cells, as well as Leydig cells.

Leptin accelerates gonadotropin-releasing hormone (GnRH) pulsatility in hypothalamic neurons, and it has a direct effect on the anterior pituitary.

Recent data indicate that leptin has a specific role in stimulating the activity of enzymes essential for the synthesis of adrenal androgens.

Leptin administration at low doses may have a permissive, threshold effect on the central networks that regulate gonadotropin secretion. However, at high levels, such as those in obese people, it can have an inhibitory effect on the gonads. Children with obesity also have increased adrenal androgen levels, which may be involved in the accelerated growth of these children before puberty.

Question 2

What does fatness & weight have to do with the onset of puberty in livestock animals?

Answer 2

Fatness: leptin synthesised by adipose tissue activates kisspeptin, which stimulates GnRH → LH pulses

In heifers:

• higher planes of nutrition lead to earlier onset of maturity
• IGF-1 (growth factor) highly correlated to body-weight gain in first six months of life