Inhibitors of oxidative stress mimic the ability of follicle-stimulating hormone to suppress apoptosis in cultured rat ovarian follicles.

Abstract

We have reported that members of the bcl-2 gene family are expressed and gonadotropin regulated in ovarian granulosa cells during follicular maturation and atresia. Because Bcl-2, a protein that prevents apoptosis in several cell types, is reported to function as an antioxidant or free radical scavenger, the present studies were designed to investigate if oxidative stress plays a role in granulosa cell apoptosis during follicular atresia in the immature rat ovary. In the first series of experiments, the role of oxidative stress in the induction of granulosa cell apoptosis was directly tested using a defined in vitro follicle culture system. Healthy antral follicles obtained from equine CG (eCG)-primed immature (27 day old) rats were incubated in serum-free medium for 24 h in the absence or presence of FSH (100 ng/ml; a control for inhibiting apoptosis), superoxide dismutase (SOD; 10-1000 U/ml), ascorbic acid (0.01-1 mM; a free radical scavenger), N-acetyl-L-cysteine (25-100 mM; a free radical scavenger and stimulator of endogenous glutathione peroxidase activity), or catalase (10-1000 U/ml). Granulosa cells within follicles incubated in medium alone exhibited extensive apoptosis after 24 h of incubation, and this onset of apoptosis was blocked by treatment with FSH (29 +/- 4% of controls; P< 0.001, n = 3). Moreover, apoptosis in follicles was also inhibited by treatment with SOD (44 +/- 4% of controls at 1000 U/ml; P < 0.01, n = 3), ascorbic acid (55 +/- 9% of controls at 1 mM; P < 0.05, n = 3), N-acetyl-L-cysteine (24 +/- 7% of controls at 100 mM; P < 0.001, n = 3), or catalase (35 +/- 6% of controls at 1000 U/ml; P < 0.001, n = 3). In the second series of experiments, complementary DNAs corresponding to secreted (SEC-SOD), copper/zinc-containing (Cu/Zn-SOD), and manganese-containing (Mn-SOD) forms of rat SOD, rat seleno-cysteine glutathione peroxidase (GSHPx), and rat catalase were isolated and used to synthesize antisense RNA probes for Northern and slot blot analysis of changes in SOD, GSHPx, and catalase gene expression during follicular maturation. In vivo priming of 25-day-old female rats for 2 days with 10 IU eCG, which promoted antral follicular growth and survival, increased levels of messenger RNA encoding SEC-SOD (216 +/- 9% of saline-treated controls, P < 0.05, n = 3) and Mn-SOD (222 +/- 14% of saline-treated controls, P < 0.05, n = 3) vs. saline-treated controls.(ABSTRACT TRUNCATED AT 400 WORDS)

Changes in the glucose-6-phosphate dehydrogenase activity in granulosa cells during follicular atresia in ewes

“…On the other hand, it is known that the antiapoptotic effect of FSH in cultured follicles (Tilly & Tilly 1995) is partially due to its stimulatory effect on the de novo synthesis of GSH (Tsai-Turton & Luderer 2006). Glutamate cysteine ligase (GCL), which catalyzes g-glutamylcysteine synthesis, is needed for the de novo synthesis of GSH and expressed in the granulosa cells of healthy follicles.…”

“…Hence, it has been proposed that inadequate protection against ROS constitutes a trigger for follicular atresia. Therefore, the survival of follicles subjected to gonadotropin stimulation is related to an increase in the expression of antioxidant enzymes (Tilly & Tilly 1995), while treatment with antioxidants blocks granulosa cell apoptosis in cultured follicles (Tilly 1996). Among the most noteworthy deleterious effects of ROS on follicular cells is the inhibition of induction of steroidogenesis by gonadotropic hormone with the loss of follicular function (Margolin et al 1990).…”

Antioxidants protect PINK1 -dependent dopaminergic neurons in Drosophila

“…Eye phenotypes were scored under microscopy. Antioxidative activity of endogenous SOD1 has been shown in both cultured cells in vitro and dog in vivo (38,39).…”

Ovarian Toxicity of 4-Vinylcyclohexene Diepoxide: A Mechanistic Model

“…The manganese (Mn) isoform is associated with mitochondria, the copper/zinc (Cu/Zn) form is associated with the cytosol, and the secreted (Sec) form is secreted to the extracellular space (30). In a recent study, the role of oxidative stress in large antral follicles in the rat was examined (46). Expression of mRNA encoding oxidative stress genes under conditions of inhibited atresia (apoptosis) was increased for M nSOD and SecSOD but was unchanged for Cu/ZnSOD, glutathione peroxidase, and catalase.…”