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Production of sexual steroids in rats during pre- and early postnatal life
Insights
Testosterone production in male rats begins during gestation and peaks shortly after birth, coinciding with brain sexual differentiation. Ovaries do not produce steroids during this critical perinatal period.
Area of Science:
- Reproductive Endocrinology
- Developmental Biology
- Neuroendocrinology
Background:
- Sexual steroids play a crucial role in sexual differentiation.
- Understanding perinatal steroidogenesis is key to comprehending reproductive development.
- Rat models are essential for studying early neurodevelopmental processes.
Purpose of the Study:
- To comprehensively map the perinatal production of sexual steroids (progesterone, estradiol, testosterone).
- To correlate steroid production with key developmental events like sexual differentiation.
- To investigate the contribution of gonads and adrenal glands to perinatal steroid levels.
Main Methods:
- Quantification of progesterone, estradiol, and testosterone levels.
- Analysis of sera, gonads (testes and ovaries), and adrenal glands.
- Study conducted from the 14th day of gestation to the 24th day of postnatal life in rats.
Main Results:
- Testosterone synthesis initiated by day 17 of gestation in testes, peaking between day 19 in utero and day 4 postpartum.
- A secondary, smaller testosterone peak observed around postnatal days 14-15.
- No detectable ovarian steroid production during the perinatal period; adrenal glands produce early postnatal progesterone.
Conclusions:
- Early testosterone surges align with the critical period for sexual differentiation of the rat brain.
- Ovarian steroidogenesis is not involved in early sexual differentiation.
- Adrenal glands are a source of progesterone in early postnatal life.
Abstract:
To get a comprehensive picture of the normal perinatal production of sexual steroids, we determined progesterone, estradiol and testosterone content in the sera, gonads and adrenal glands of rats of both sexes between 14th day of gestation and 24th day of postnatal life. The first sign of testosterone synthesis in the testicles could be detected on the 17th day of gestation followed by a large peak between the 19th intrauterine and 4th postnatal day. A second smaller increase in testosterone production was found around the 14-15th postnatal days. The first peak matches well the time of the critical period of sexual differentiation of the rats brain. No detectable amount of steroid were found in the ovary during the perinatal period. The ovaries seem not to be involved in the early period of sexual differentiation. The small quantity of progesterone found in the sera of early postnatal animals is produced by the adrenal glands.