Radiotherapy causes destruction of
tumor cells, but also threatens the integrity and
survival of surrounding normal
cells. Then,
woman submitted to irradiation for
cancer treatment may present permanent
ovary damage, resulting in impaired
fertility. The objective of this study was to investigate the effects of
therapeutic doses of
ionizing radiation (IR), used for
ovarian cancer treatment in
humans, on bovine
cumulus-
oocyte complexes (COCs) as
experimental model. Bovine
ovaries were exposed to 0.9 Gy, 1.8 Gy, 3.6 Gy or 18.6 Gy IR, and then COCs were collected and used to evaluate (a)
oocyte nuclear maturation; (b) presence of phosphorylated H2A.X (γH2AX), as an
indicator of
DNA double-strand breaks (DSBs); and (c) expression of
genes involved in
DNA repair (TP53BP1, RAD52, ATM, XRCC6 and XRCC5) and
apoptosis (BAX). The
radiation doses tested in this study had no detrimental effects on nuclear maturation and did not increase γH2AX in the
oocytes. However, IR
treatment altered the
mRNA abundance of RAD52 (RAD52 homolog,
DNA repair protein) and BAX (
BCL2-associated X protein). We conclude that although IR doses had no apparent effect on
oocyte nuclear maturation and
DNA damage, molecular pathways involved in
DNA repair and
apoptosis were affected by IR exposure in
cumulus cells.(AU)