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Dynamics of bioactive luteinizing hormone-human chorionic gonadotropin during the first 7 days of life
1Department of Pediatrics, Facultad de Medicina Universidad del Valle, Cali, Colombia.
Insights
Neonatal serum bioactivity of luteinizing hormone-human chorionic gonadotropin (B-LH) shows distinct patterns in males and females. Pulsatile B-LH secretion is present in newborns, with males exhibiting a secondary rise after day 4, unlike females.
Area of Science:
- Endocrinology
- Neonatal Physiology
- Reproductive Biology
Background:
- Luteinizing hormone-human chorionic gonadotropin bioactivity (B-LH) plays a crucial role in early development.
- Understanding neonatal gonadotropin dynamics is essential for comprehending postnatal endocrine changes.
Purpose of the Study:
- To investigate the temporal patterns of serum B-LH in newborns during the first week of life.
- To determine if pulsatile B-LH secretion occurs in neonates.
- To identify sex-specific differences in neonatal B-LH levels and secretion patterns.
Main Methods:
- Daily serum B-LH measurements in male and female newborns for the first 7 days of life.
- Frequent (every 20 min for 2 h) serum B-LH sampling on day 7 to assess pulsatility.
- Statistical analysis to compare B-LH levels between sexes and over time.
Main Results:
- Serum B-LH levels were initially elevated in both sexes, declining thereafter.
- Male neonates showed a nadir on day 4 followed by a significant secondary rise by day 7.
- Female neonates exhibited a continuous decline in B-LH levels from day 1 to day 7.
- Pulsatile B-LH secretion was observed in both male and female neonates on day 7.
Conclusions:
- Pulsatility of gonadotropin secretion is characteristic of neonates by 7 days of age.
- A significant dichotomy exists in B-LH levels between male and female neonates.
- The male-specific rise in B-LH may contribute to the postnatal increase in testosterone observed in infant males.
Abstract:
Serum luteinizing hormone-human chorionic gonadotropin bioactivity (B-LH) was measured daily in seven male and four female full-term newborns during the first 7 days of life. The B-LH levels were elevated in both sexes during the 1st day of life; subsequently, values decreased in both sexes. In males, they reached a nadir on the 4th day of life. A gradual secondary rise was then observed with B-LH levels on the 7th day significantly higher than on day 4 (p less than 0.025). By contrast, the B-LH levels in the females continued a gradual decline to levels significantly lower on day 7 as compared to day 4 (p less than 0.05). To determine whether pulsatile B-LH secretion occurs in newborns, serum concentrations were measured every 20 min for 2 h in eight male and seven female full-term neonates on the 7th day of life. Pulsatile secretion of B-LH was detected in six males and six females. This study demonstrates that pulsatility of gonadotropin secretion is characteristic of neonates as early as 7 days of life and that there is a dichotomy between the levels of B-LH in males and females; levels in females decline progressively from day 1 through 7, whereas in males, a nadir is reached on day 4 with a secondary rise developing thereafter. This male sex-specific rise is presumably the drive responsible for the characteristic postnatal increase in testosterone which peaks at 1 to 2 months of age.