A specific adenylyl cyclase inhibitor (DDA) and a cyclic AMP-dependent protein kinase inhibitor (H-89) block the action of equine growth hormone on in vitro maturation of equine oocytes.

Pereira, G.R., Lorenzo, P.L., Carneiro, G.F., Bilodeau-Goeseels, S., Kastelic, J.P., and Liu, I.K.M. (2014). "A specific adenylyl cyclase inhibitor (DDA) and a cyclic AMP-dependent protein kinase inhibitor (H-89) block the action of equine growth hormone on in vitro maturation of equine oocytes.", Zygote, 23(6), pp. 795-801. doi : 10.1017/S0967199414000434  Access to full text

Abstract

The objectives of this study were firstly to determine whether the stimulatory function of equine growth hormone (eGH) on equine oocyte maturation in vitro is mediated via cyclic adenosine monophosphate (cAMP); and secondly if the addition of eGH in vitro influences oocyte nuclear maturation and if this effect is removed when GH inhibitors are added to the culture. Cumulus–oocyte complexes (COCs) were recovered from follicles <25 mm in diameter and randomly allocated as follows: (i) control (no additives); and (ii) 400 ng/ml of eGH. A specific inhibitor against cyclic AMP-dependent protein kinase (H-89; 109, 1011 or 1015 M concentration) and a specific adenylate cyclase inhibitor, 2′,3′-dideoxyadenosine (DDA; 108, 1010 or 1014 M concentration) were used to observe whether they could block the eGH effect. After 30 h of in vitro maturation at 38.5°C with 5% CO2 in air, oocytes were stained with 10 μg/ml of Hoechst to evaluate nuclear status. More mature oocytes (P < 0.05) were detected when COCs were incubated with eGH (29 of 84; 34.5%) than in the control group (18 of 82; 21.9%). The H-89 inhibitor used at a concentration of 109 M (4 of 29; 13.8%) decreased (P < 0.05) the number of oocytes reaching nuclear maturation when compared with eGH (11 of 29; 38%). The DDA inhibitor at a concentration of 108 M (2 of 27; 7.4%) also reduced (P < 0.05) the number of oocytes reaching maturity when compared with the eGH group (9 of 30; 30%). Results from the present study show that H-89 and DDA can be used in vitro to block the eGH effect on equine oocyte maturation.

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