Increased endogenous level of melatonin in preovulatory human follicles does not directly influence progesterone production.
Level 4 - case-series / case-control
Cross-sectional human follicular fluid analysis combined with in vitro laboratory cell culture
PubMed 14556825 · doi:10.1016/s0015-0282(03)01008-2
What was done
The authors evaluated the relationship between follicular melatonin and steroid hormones in 36 women undergoing in vitro fertilization for tubal or male factor infertility. Follicular fluid was collected to measure melatonin, progesterone, estradiol, and testosterone in large preovulatory versus small growing follicles. Granulosa cells were also cultured in vitro to test whether melatonin stimulates progesterone production.
What was found
Follicular fluid melatonin correlated positively with progesterone concentrations. Melatonin, progesterone, and estradiol concentrations were significantly higher, and testosterone was significantly lower, in large follicles compared with small follicles. In vitro melatonin did not stimulate progesterone production by granulosa cells. The abstract reports no numerical values or correlation statistics.
Why it matters
This study shows that while melatonin accumulates in mature follicles alongside progesterone, it does not directly stimulate granulosa cell progesterone synthesis. This suggests any functional role of melatonin in follicular steroidogenesis is indirect.
Limits
The sample size is small (n = 36) and restricted to infertile women undergoing ovarian stimulation for IVF. The abstract omits exact numerical concentrations, effect sizes, and p-values, and in vitro cell culture does not fully replicate intact ovarian physiology.
Cited by
- supports The female body naturally increases melatonin production during ovulation to mitigate oxidative stress to the ovary.