Dual Effects of Hydrogen Sulfide Donor on Meiosis and Cumulus Expansion of Porcine Cumulus-Oocyte Complexes

<div><p>Hydrogen sulfide (H₂S) has been revealed to be a signal molecule with second messenger action in the somatic cells of many tissues, including the reproductive tract. The aim of this study was to address how exogenous H₂S acts on the meiotic maturation of porcine oocytes, including key maturation factors such as MPF and MAPK, and cumulus expansion intensity of cumulus-oocyte complexes. We observed that the H₂S donor, Na₂S, accelerated oocyte <i>in vitro</i> maturation in a dose-dependent manner, following an increase of MPF activity around germinal vesicle breakdown. Concurrently, the H₂S donor affected cumulus expansion, monitored by hyaluronic acid production. Our results suggest that the H₂S donor influences oocyte maturation and thus also participates in the regulation of cumulus expansion. The exogenous H₂S donor apparently affects key signal pathways of oocyte maturation and cumulus expansion, resulting in faster oocyte maturation with little need of cumulus expansion.</p></div

Effect of Na₂S on HA content in expanded cumulus.

<p>(A) Total and retained HA content in COCs cultivated with 150–900 µM Na₂S for 48 hs, total HA is related to the control group. (B) Total and retained HA content in COCs during <i>in vitro</i> cultivation with 300 µM Na₂S over 12 h time scale, total HA is related to the control group after 48 h cultivation. (C) Total and retained HA content in COCs and OOXs cultivated with or without H₂S donor, total HA is related to the control group of COCs. H₂S: 300 µM Na₂S. ^a,b,cStatistically significant differences among experimental groups in total HA, ^1,2statistically significant differences among experimental groups in retained HA, *statistically significant differences in total HA between control and H₂S groups (P<0.05).</p

Effect of Na₂S on partenogenetic development of porcine oocytes.

<p>Oocytes were matured with or without Na₂S and partenogenetically activated using calcium ionophore. Pronucleus formation after 24 h zygote culture, cleavage rate after 2 days and blastocyst achievement after 7 days presumptive embryos culture were evaluated (%±SE).</p><p>H₂S: 300 µM Na₂S during oocyte maturation.</p><p>*Statistically significant differences between control and H₂S group – in column (P<0.05).</p

Effect of Na₂S on MPF and MAPK activities during oocyte cultivation.

<p>Representative autoradiograms and signal quantifications of phosphorylated histone H1 (A) and MBP (B) reflecting MPF and MAPK activity, respectively. Kinase activity was measured in oocytes cultivated with or without Na₂S over 2 h time scale. The kinase activity was related to oocytes cultivated for 24 hs. C: control; H₂S: 300 µM Na₂S. *Statistically significant differences between control and H₂S groups (P<0.05).</p

Effect of Na₂S on meiotic resumption and transition to meiosis II during oocyte cultivation.

<p>Proportion of GVBD (A) and meiosis I to II transition (B) in oocytes during <i>in vitro</i> cultivation over 2 h time scale. H₂S: 300 µM Na₂S. *Statistically significant differences between control and H₂S groups (P<0.05).</p

Effect of Na₂S on meiosis resumption and transition to meiosis II in DOs.

<p>Proportion of GVBD (A) and meiosis I to II transition (B) during <i>in vitro</i> cultivation after 20 and 30 h <i>in vitro</i> cultivation, respectively. H₂S: 300 µM Na₂S. ^a,b,cStatistically significant differences among experimental groups (P<0.05).</p

Effect of different Na₂S concentrations on meiosis resumption and transition to meiosis II in oocytes.

<p>Proportion of GVBD (A) and meiosis I to II transition (B) during <i>in vitro</i> cultivation after 20 and 30 h <i>in vitro</i> cultivation, respectively. ^a,b,cStatistically significant differences among experimental groups (P<0.05).</p