Influence of Nitric Oxide on Steroid Synthesis, Growth and Apoptosis of Buffalo (Bubalus bubalis) Granulosa Cells In vitro

Chronic nitrate administration increases the expression the genes involved in the browning of white adipose tissue in female rats

Nitrate, a nitric oxide (NO) donor, has antiobesity effect in female rats. This study hypothesized that the antiobesity effect of nitrate in female rats is due to the browning of white adipose tissue (WAT). Female Wistar rats (aged 8 months) were divided into two groups (n = 10/group): the control group received tap water and the nitrate group received water containing 100 mg/L of sodium nitrate for 9 months. At months 0, 3, 6, and 9, obesity indices were measured. At month 9, gonadal adipose tissue was used to measure messenger RNA (mRNA) and protein levels of peroxisome proliferator-activated receptor-γ (PPAR-γ), PPAR-γ coactivator 1-α (PGC1-α), uncoupling protein 1 (UCP1), and adipocyte density and area. After the 9-month intervention, nitrate-treated rats had lower body weight, body mass index, thoracic circumference, and abdominal circumference by 6.4% (p = .012), 9.1% (p = .029), 6.0% (p = .056), and 5.7% (p = .098), respectively. In addition, nitrate-treated rats had higher PPAR-γ (mRNA: 1.78-fold, p = .016 and protein: 19%, p = .076), PGC1-α (mRNA: 1.69-fold, p = .012 and protein: 68%, p = .001), and UCP1 (mRNA: 2.50-fold, p = .001 and protein: 81%, p = .001) in gonadal adipose tissue. Nitrate also reduced adipocyte area by 35% (p = .054) and increased adipocyte density by 31% (p = .086). In conclusion, antiobesity effect of nitrate in female rats is associated with increased browning of gonadal adipose tissue as indicated by higher expression of PPAR-γ, PGC1-α, and UCP1 and reduced adipocyte area and increased adipocyte density.

Effects of nitric oxide on steroidogenesis and apoptosis in goat luteinized granulosa cells

The aim of this study was to investigate effects of nitric oxide (NO) on steroidogenesis and apoptosis in goat luteinized granulosa cells (LGCs). We cultured goat LGCs from healthy follicles in culture medium supplemented with the NO donor sodium nitroprusside (SNP) or the NO synthase inhibitor N_ω-Nitro-l-arginine methyl ester hydrochloride (l-NAME), then examined steroid synthesis, oxidative stress and apoptosis in vitro. The results showed that SNP treatment significantly increased the cGMP concentration in the LGCs (P < 0.05), whereas the l-NAME treatment significantly decreased cGMP concentration (P < 0.05). Then Inhibition of NO production significantly inhibited the expression of CYP19A1, a key gene that is involved in sex steroid hormones synthesis and is responsible for the decrease of E₂. Inhibition of NO production resulted in an increased percentage of apoptosis, which was accompanied by upregulating expression levels of apoptosis-related markers BAX, CASP3 and CASP9. These data indicate that NO is required for goat LGCs steroidogenesis and cell survival. Furthermore, Inhibition of NO production decreased the expression of mitochondrial biogenesis related genes and proteins (PPARGC1A, NRF-1 and TFAM) and the mtDNA copy number. Simultaneously, inhibition of NO production suppressed the transcription and translation of SOD, GPX1, and CAT, and decreased the glutathione level and increased the 8-OHdG level. However, SNP treatment increased the expression of genes involved in mitochondrial function and biogenesis, and elevated the anti-oxidant stress system and steroid synthesis. Together, our results indicate that NO may up-regulate the expression of PPARGC1A and its downstream factors through the cGMP pathway, thereby decreasing granulosa cell apoptosis, and may participate in the regulation of granulocyte steroid production through the mitochondrial-dependent pathway.