Changes in serum FSH concentrations in the pig during development

Area of Science:

• Reproductive Endocrinology
• Developmental Biology
• Comparative Physiology

Background:

• Follicle-stimulating hormone (FSH) plays a critical role in reproductive development.
• Understanding FSH dynamics in developing pigs provides insights into mammalian reproductive physiology.
• Limited data exists on FSH concentrations during fetal and early postnatal development in swine.

Purpose of the Study:

• To characterize serum FSH concentrations in pigs from the fetal stage through prepuberty.
• To investigate the relationship between FSH levels and gonadal development in male and female pigs.
• To examine the effects of specific reproductive conditions (cryptorchidism, castration, freemartinism) on FSH levels.

Main Methods:

• Serum samples collected from pigs at various developmental stages (40 days postcoitum to 25 weeks postnatal).
• FSH concentrations measured using immunoassays.
• FSH levels analyzed in control, unilaterally cryptorchid, freemartin, and castrated prepubertal pigs.

Main Results:

• Fetal pigs (males and females) had low FSH (<2 ng/ml) until 80 days postcoitum.
• Female fetuses and neonates showed elevated and stable FSH (7.9-16.3 ng/ml).
• Male pigs exhibited a rise in FSH (to 22.5 ng/ml) in the first 3 weeks post-birth, followed by a decline, correlating with gonadal development.
• Unilateral cryptorchidism had no effect, while castration significantly increased FSH levels.
• Freemartin pigs displayed FSH levels similar to females.

Conclusions:

• Serum FSH concentrations exhibit distinct temporal patterns in male and female pigs during fetal and prepubertal development.
• FSH changes in males appear linked to gonadal development, unlike in females.
• Castration significantly impacts FSH levels, suggesting a feedback mechanism.
• These findings contribute to understanding swine reproductive endocrinology and development.