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Hypophyso-gonadal function in humans during the first year of life. 1. Evidence for testicular activity in early
Insights
Neonatal male infants show a significant surge in testosterone during the first three months of life, indicating active testicular function and potential implications for future development. This early hormonal activity suggests a maturing hypothalamo-pituitary-gonadal axis.
Area of Science:
- Endocrinology
- Pediatric Endocrinology
- Reproductive Biology
Background:
- Testosterone and androstenedione levels are crucial for male development.
- Understanding early hormonal profiles in infants is key to assessing hypothalamo-pituitary-gonadal axis maturation.
Purpose of the Study:
- To measure and compare total and unbound testosterone, and Delta(4)-androstenedione levels in cord blood and infant plasma.
- To analyze the changes in these steroids and pituitary gonadotropins (FSH and LH) during the first year of life in male and female infants.
Main Methods:
- Analysis of total and unbound testosterone and Delta(4)-androstenedione in 104 cord blood samples.
- Measurement of sexual steroids and pituitary gonadotropins in 46 male and 34 female infants aged up to 1 year.
Main Results:
- Male neonates had higher total and unbound testosterone than females. Male infants exhibited a significant testosterone surge in the first 3 months, decreasing to prepubertal levels by 7-12 months.
- Follicle-stimulating hormone and luteinizing hormone levels were significantly higher in males than females, with no correlation to age or testosterone levels.
- Female infants maintained stable, low testosterone levels throughout the first year.
Conclusions:
- The testes are active in the early neonatal period, suggesting progressive maturation of the hypothalamo-pituitary-gonadal axis.
- The early testosterone surge in males may play a role in future life patterns.
- Hormonal profiles differ significantly between sexes in early infancy.
Abstract:
Total and unbound testosterone and Delta(4)-androstenedione have been determined in 104 cord blood samples. The same sexual steroids and pituitary gonadotropins have been measured in 46 normal male infants aged 27-348 days and 34 normal female infants aged 19-332 days. In cord blood of female neonates mean total and unbound testosterone was 29.6+/-7.5 and 0.89+/-0.4 ng/100 ml, respectively (mean+/-1 SD); Delta(4)-androstenedione was 93+/-38 ng/100 ml. In male neonates mean plasma total and unbound testosterone was 38.9+/-10.8 and 1.12+/-0.4 ng/100 ml; Delta(4)-androstenedione was 85+/-27 ng/100 ml. In female infants testosterone concentrations remained constant during the 1st yr of life with a mean concentration of 7+/-3 ng/100 ml. Mean unbound testosterone and Delta(4)-androstenedione concentrations were 0.05+/-0.03 and 16.7+/-8.3 ng/100 ml, respectively. Mean plasma levels of follicle-stimulating hormone and luteinizing hormone were 8.7+/-3.3 and 12.9+/-7.7 mU/ml. In male infants mean plasma total testosterone concentration increased to 208+/-68 ng/100 ml from birth to 1-3 mo of age, decreasing thereafter to 95+/-53 ng/100 ml at 3-5 mo, 23.2+/-18 ng/100 ml at 5-7 mo, and reached prepubertal levels (6.6+/-4.6 ng/100 ml) at 7-12 mo. Mean unbound testosterone concentration plateaued from birth to 1-3 mo of age (1.3+/-0.2 ng/100 ml) decreasing to prepubertal values very rapidly. Mean Delta(4)-androstenedione concentration, although progressively decreasing during the 1st yr of life to 11.7+/-4.5 ng/100 ml, was higher than in the female at 1-3 mo of life (34+/-11 ng/100 ml). Mean plasma level of follicle-stimulating hormone was 6.7+/-2.9 mU/ml, and that of luteinizing hormone was 19.7+/-13.5 mU/ml, significantly higher than in the female. There was no correlation between gonadotropin and age or testosterone. The present data demonstrate that the testes are active during the first natal period. It is tempting to correlate this phenomenon to a progressive maturation of the hypothalamo-pituitary-gonadal axis. It is possible that the surge in testosterone occurring the first 3 mo could play a role in the future life pattern of the male human being.
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