P–139 The role of hormones and LH receptor expression of granulosa cells collected from large and small follicles in natural/minimal stimulation cycle IVF

Study question

Do different follicle sizes influence gonadotropins (LH, FSH) and sex steroid (estradiol) in follicular fluids and LH receptor expression (LHCGR) in cumulus oocyte complexes (COCs)?

Summary answer

It was found that differences in levels of FSH, estradiol values and LHCGR mRNA expression level in COCs between small and large follicles.

What is known already

The maturity rate in oocytes of small follicle is significantly lower compared to that of large follicles.

Study design, size, duration

After obtaining written consents from 78 infertile patients, we aspirated the large (>15 mm) and small (<5 mm) follicles, and collected follicular fluids at oocyte retrieval.

Participants/materials, setting, methods

We measured levels of LH, FSH and estradiol by enzyme immunoassay from large and small follicular fluids after oocytes retrievals. All collected oocytes were distinguished from large and small follicles, we confirmed the maturity of retrieved oocytes by the presence of first polar body. Then we extracted total RNA from granulosa cells and measured mRNA expression of LHCGR, encoding the human LH receptor, by quantitative real-time PCR. Each value was normalized to ACTB mRNA levels.

Main results and the role of chance

LH levels were nearly equal between small and large follicles (P = 0.8356). Whereas FSH and estradiol levels were significantly lower in small follicles (P < 0.0001). The expression levels of LHCGR mRNA were significantly lower in small follicles than in large follicles during natural cycles. The maturity rate in oocytes of small follicle was significantly lower compared to that of large follicles (96.0% vs. 21.7%, P < 0001).

Limitations, reasons for caution

The main limitation of the present study was collected by 42 natural cycles and 36 mild stimulation cycles with letrozole following low-dose clomiphene.

Wider implications of the findings: In spite of almost the same LH levels between two groups, the reason why the significantly lower maturation rates of oocytes collected from small follicles is poor LHCGR mRNA expression due to insufficient granulosa cells glowth because of low FSH and estradiol levels.

Trial registration number

Not applicable