Vasoactive Intestinal Peptide and Its Receptors in Human Ovarian Cortical Follicles

BACKGROUND: Ovarian cryopreservation is one option for fertility preservation in patients with cancer. The danger of reseeding malignancies could be eliminated by in vitro maturation of primordial follicles from the frozen-thawed tissue. However, the development of this system is hindered by uncertainties regarding factors that activate primordial follicles. Neuronal growth factors such as vasoactive intestinal peptide (VIP) play important roles in early mammalian folliculogenesis. There are no data on the expression of VIP and its vasoactive intestinal peptide pituitary adenylate cyclase 1 and 2 receptors (VPAC1-R and VPAC2-R) in human preantral follicles. METHODOLOGY/PRINCIPAL FINDINGS: Tissue samples from 14 human fetal ovaries and 40 ovaries from girls/women were prepared to test for the expression of VIP, VPAC1-R, and VPAC2-R on the protein (immunohistochemisty) and mRNA (reverse transcription polymerase chain reaction) levels. Immunohistochemistry staining was mostly weak, especially in fetal samples. The VIP protein was identified in oocytes and granulosa cells (GCs) in the fetal samples from 22 gestational weeks (GW) onwards. In girls/women, VIP follicular staining (oocytes and GCs) was identified in 45% of samples. VPAC1-R protein was identified in follicles in all fetal samples from 22GW onwards and in 63% of the samples from girls/women (GC staining only in 40%). VPAC2-R protein was identified in follicles in 33% of fetal samples and 47% of the samples from girls/women. The mRNA transcripts for VIP, VPAC1-R, and VPAC2-R were identified in ovarian extracts from fetuses and women. CONCLUSIONS: VIP and its two receptors are expressed in human ovarian preantral follicles. However, their weak staining suggests they have limited roles in early follicular growth. To elucidate if VIP activates human primordial follicles, it should be added to the culture medium

A previous caesarean section is not a risk factor for tubal abnormalities in the infertile population

In this retrospective cohort study of 1716 cases of women undergoing infertility treatment between the years 1999–2012, we aimed to identify whether parturients with a previous surgical history are at a higher risk for tubal abnormalities as determined by hysterosalpingography (HSG) in this infertile population. Amongst the study population, tubal obstruction was identified on HSG in 15.8% of patients with no past history of an abdominal surgery and 16.3% of patients with a previous caesarean section (CS) delivery. These rates were significantly lower than those for women with a previous gynaecological surgery (34.7%) or abdominal surgery (27%) (p < .001 for all comparisons). Our results suggest that past history of CS poses no additional risk for tubal abnormality within the infertile population, whereas a history of other abdominal or gynaecological surgical procedures doubles this risk.Impact Statement What is already known on this subject? While numerous risk factors for tubal factor infertility have been established, to date, the relation between previous abdominal surgeries and the risk for tubal factor infertility remains inconclusive. What the results of this study add? In this study, we aimed to evaluate the correlation between previous CS history and the risk for having tubal factor infertility. Our results demonstrated that previous caesarean section delivery does not increase the risk for tubal factor infertility in the infertile population, whereas history of other abdominal or gynaecological surgical procedures doubles this risk. What the implications are of these findings for clinical practice and/or further research? Further research is needed for further evaluation of this association and its clinical implications

Does ‘Dual Trigger’ Increase Oocyte Maturation Rate?

The aim of this study was to evaluate the oocyte maturation rate when GnRH-a and hCG (dual trigger) are co-administered, compared to the standard hCG trigger within the same patient. Included in the study were GnRH antagonist ICSI cycles performed in 137 patients who had a standard hCG trigger cycle and a dual trigger cycle between 1/1/2013 and 31/12/2017. The mean patient age (35.9 ± 5.6 and 35.2 ± 5.9; <0.001), FSH dose (4140 ± 2065 and 3585 ± 1858; <0.01), number of retrieved oocytes (10.3 ± 6.2 and 8.9 ± 6.1; 0.011) were higher in the dual trigger group compared to the hCG trigger group, oocyte maturation rate was identical. Maturation rate following dual trigger was significantly higher among 34 patients who had a maturation rate of <70% following hCG triggering and among 16 patients with a maturation rate <50% rate following hCG trigger (54% vs. 74%, p < .001 and 44% vs. 73%, p = .006; respectively). In conclusion, co-administration of GnRH agonist and hCG for final oocyte maturation substantially increased the oocyte maturation rate in patients with low oocyte maturation rate in their hCG triggered cycle, but not in an unselected population of patients.IMPACT STATEMENT What is already known on this subject? The co-administration of GnRH agonist and hCG for final oocyte maturation prior to oocyte retrieval may improve IVF outcome in patients with a high proportion of immature oocytes. The few studies on dual trigger in patients with a high proportion of immature oocytes or in normal responders have shown conflicting results. What do the results of this study add? We found that co-administration of GnRH agonist and hCG for final oocyte maturation substantially increased the oocyte maturation rate in patients with low oocyte maturation rate in their hCG triggered cycle, but not in an unselected population of patients. What are the implications of these findings for clinical practice and/or further research? The results of this study implicate that in selected population with low oocyte maturation rate, there is an advantage in using dual trigger. However, larger prospective trials are warranted to better assess oocyte response in dual trigger

Representative RT-PCR gel illustrating expression of the VIP, VPAC1-R and VPAC2-R genes in fetal and adult ovaries.

<p>(A) VIP gene (134 base pairs), (B) VPAC1-R gene (97 base pairs), (C) VPAC2-R gene (155 base pairs), (D) DHFR gene as positive control (231base pairs). Sample 1: Ovary from a 21-year-old woman, Sample 2: Ovary from a 29-year-old woman, Sample 3: Ovary from a 39-year-old woman, Sample 4: Ovary from a 21-GW-old fetus, Sample 5: Ovary from a 23-GW-old fetus, Sample 6: Ovary from a 25-GW-old fetus, Sample 7: Ovary from a 27-GW-old fetus. M: Marker (100 base pair DNA ladder, QIAGEN), +: RT presence, -: RT absence.</p

IMH photographs of VIP protein expression.

<p>(A) Section of human ovary from a 22-GW-old fetus. Note the primordial follicles, weak red-brown staining indicating VIP expression in oocytes (full cytoplasmic and nuclear staining), and weak staining in a portion of the GC and stroma cells. Original magnification X400. (B) Section of human ovary from a 6-year-old girl. Note the primordial follicles with red-brown staining indicating VIP protein expression in the oocyte (mainly cytoplasmic staining and nuclear staining), and in a portion of the GC and a portion of the stroma cells. Original magnification X400. (C) Positive control for VIP protein expression of section of mouse brain. Note the red-brown staining in the sample. Original magnification X400. (D) Negative control for the same ovarian section as in panel A. Note the primordial follicles with the overall blue staining and the lack of red-brown staining. Original magnification X400. (E) Negative control for the same ovarian section as in panel B. Note the primordial follicles with overall blue staining and the lack of red-brown staining. Original magnification X400.</p

Protein expression (IMH) of VIP, VPAC1-R and VPAC2-R in human ovaries.

<p><u>Note</u>: IMH = immunohistochemistry, GW = gestational weeks. Percentages represent the proportion of the samples with follicular staining.</p><p>Staining intensities: + = positive staining; full/partial = full or partial cytoplasmic staining.</p

IMH photographs of VPAC2-R protein expression.

<p>(A) Section of a human ovary from the same fetus as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0037015#pone-0037015-g001" target="_blank">Figure 1</a> (A) and (D). Note the red-brown staining indicating VPAC2-R expression in the oocytes (full weak cytoplasmic staining with nuclear staining), in a portion of the GC and stroma cells. Original magnification X400. (B) Section of human ovary from the same woman as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0037015#pone-0037015-g002" target="_blank">Figure 2</a> (A) and (B). Note the secondary follicle (full cytoplasmic staining with nuclear staining), with red-brown staining in the GC and stroma cells. Original magnification X400. (C) Negative control for the same ovarian section as in panel A. Note the primordial follicles with overall blue staining and lack of red-brown staining. Original magnification X400. (D) Negative control for the same ovarian section as in panel B. Note the primordial follicles with overall blue staining and lack of red-brown staining. Original magnification X400.</p

IMH photographs of VPAC1-R protein expression.

<p>(A) Section of human ovary from a 22-year-old woman. Note the primordial follicles, with red-brown staining indicating VPAC1-R expression in the oocytes (full cytoplasmic staining and nuclear staining), and in a portion of the GC and stroma cells. Original magnification X400. (B) Negative control for the same ovarian section as in panel A. Note the primordial follicle, overall blue staining, and lack of red-brown staining. Original magnification X400.</p