Modulation of aquaporins 3 and 9 after exposure of ovine ovarian tissue to cryoprotectants followed by in vitro culture.

Our aim has been to evaluate the effect of cryoprotective agents (CPAs) on the exposure, vitrification (VIT), and in vitro culture (IVC) of ovarian tissue with regard to the expression and immunolocalization of aquaporins (AQPs) 3 and 9 in ovine preantral follicles. Tissues were treated as follows: Experiment I: (1) control (without exposure to CPAs), (2) e-EG (exposure to ethylene glycol), (3) er-EG (exposure to and removal of EG), (4) e-DMSO (exposure to dimethyl sulfoxide), (5) er-DMSO (exposure to and removal of DMSO), (6) e-EG+DMSO (exposure to EG+DMSO), (7) er-EG+DMSO (exposure to and removal of EG+DMSO); Experiment II: (1) control, (2) VIT, (3) IVC, (4) VIT-IVC. In Experiment I, following er-EG or er-DMSO, tissue showed the down-regulation (P < 0.05) of AQP3 mRNA. The mRNA transcript levels were reduced (P < 0.05) for AQP9 in tissue following er-EG+DMSO. Immunolocalization was positive for both proteins (AQP3 and AQP9) on ovine preantral follicles following all treatments, except in the e-EG+DMSO group. In Experiment II, the mRNA levels of AQP3 and AQP9 following VIT treatment were similar (P > 0.05) to that of the control group. Nevertheless, VIT-IVC treatment led to the down-regulation of mRNA of AQP3 and AQP9. Thus, AQP3 and AQP9 act in a mutually dependent way, maintaining the cell homeostasis that is essential for the ovary cryopreservation process. Furthermore, the changes in the expression profiles of mRNA and protein after culture are a strong indicator that in vitro conditions have to be strictly controlled to ensure follicle viability and functionality.