[Steroids in the reproductive function regulation in fish]

Area of Science:

• Reproductive biology
• Endocrinology
• Ichthyology

Context:

• Investigates sex steroid dynamics in stellate sturgeon (Acipenser stellatus) during the reproductive cycle.
• Examines the relationship between circulating steroid hormones and their tissue-specific binding in the brain and gonads.

Purpose:

• To elucidate the changes in cortisol, testosterone, and progesterone concentrations in coelomic fluid and blood serum following ovulation.
• To determine the alterations in sex steroid cytosol binding in the brain (forebrain, hypothalamus) and gonads before and after maturation and ovulation.
• To establish correlations between blood sex steroid levels and their specific binding in target tissues.

Summary:

• Post-ovulation, stellate sturgeon exhibited lower cortisol and testosterone concentrations in coelomic fluid compared to blood serum, while progesterone levels were lower in the blood.
• Specific cytosol binding of sex steroids in the brain and gonads demonstrated distinct patterns before and after maturation.
• Androgen binding in the forebrain decreased sharply after ovulation, whereas estrogen binding in the hypothalamus peaked post-maturation and ovulation.
• A correlation was observed between blood sex steroid concentrations and their specific binding within the brain and gonads cytosol.

Impact:

• Provides crucial insights into the neuroendocrine regulation of reproduction in sturgeon.
• Highlights the differential distribution and binding of sex steroids in key reproductive tissues.
• Contributes to a better understanding of hormonal control during fish maturation and spawning.