Effect of nitric oxide on ovarian estradiol release and its synthesis enzyme expression, in the first proestrus in the rat

MORALES LD; DELSOUC MB; VALLCANERAS S; DELGADO SM; CASAIS M

Congreso; XXXII Reunión Científica Anual de la Sociedad de Biología de Cuyo; 2014

The nitric oxide (NO) is a gaseous neurotransmitter involved in steroidogenesis and follicular development. In the first proestrus (PE), the stage where is evident follicular maturation which lead to the first ovulation, the ovarian steroid hormone with major participation is estradiol (E2). Taking into account this information, the aims of this work, in the first PE, were to study the effects of NO synthase (NOS) inhibitors and a NO donor on: 1) the release of E2 in ovary without neural influence (Ov), 2) ovarian gene expression of P450 aromatase (P450arom, E2 synthesis enzyme). The Ov was incubated in Krebs-Ringer buffer at 37°C (control group). Inhibitors of NOS: aminoguanidine 400 µM (AG) and L-nitroarginine methyl ester 100 µM (L-NAME), selective and non-selective of inducible NOS, respectively; and NO donor: sodium nitroprusside 100 µM (SNP), were added in Ov. E2 was determined by RIA at 120 min and 180 min. One-way ANOVA and Tukey test were used (p<0.05). The gene expression of P450arom was determined by RT-PCR at 180 min. AG vs control group showed tendency to increase E2. L-NAME vs control group increased E2 only at 120min (p<0.01). In contrast, SNP vs control group decreased E2 at 120 min and 180 min (p<0.05), with tendency to decrease the gene expression of P450arom at 180 min. In the first PE in the rat, NO acts as a negative regulator on E2 release without significative changes on gene expression of its synthesis enzyme at 180 min.