The expression of leptin receptor in the ovary of the queen: leptin receptor expression in queen ovary.

Leptin is a Ob gene product secreted mainly by adipose tissue. Several reports showed leptin production by other tissue including the ovary. The action of leptin is mediated upon binding to its receptor widely expressed in reproductive tissues in different species. In fact, there are growing evidences that leptin plays an important role in the modulation of reproductive functions. Therefore, the aim of this study was to evaluate in the queen, the expression of leptin receptor during the functional ovarian cycle and pregnancy. We found that the ovaries of the queen express leptin receptor in all the examined phases. The highest leptin receptor expression was found in the luteal phase (pseudopregnancy, pregnancy) compared to other phases of the cycle (anestrus, proestrus, estrus). The variations in the expression of leptin receptor suggest a likely implication of leptin in the modulation of ovarian activity, in the examined species.

Leptin and queen ovary: new insights about ovulation.

Leptin has been proven to be crucial in the ovulatory process. Aims of this study are to assess the expression of leptin receptor (Ob-R) in the ovaries of queens at estrus and to evaluate the capability of leptin in modulating ovarian contractility in vitro. Right ovaries underwent immunoblot analysis. Left ovaries were mounted in an organ bath under physiological condition and exposed to murine leptin (10(-6) M). Immunoblot analysis showed that the queen ovary expresses leptin receptor at estrus. Leptin at the dose of 10(-6) M significantly reduced the contractile activity of the ovary. The presence of ovarian Ob-R and leptin inhibitory effects on ovarian contractility suggest leptin implication in the modulation of ovarian activity, as well as in ovulatory disorders.

Roles of reactive oxygen species in female reproduction.

Reactive oxygen species (ROS) are highly reactive oxidizing agents. Cells, under aerobic conditions, have a defence system against ROS, and in normal circumstances, there is an appropriate balance between pro-oxidants and antioxidants. When an overproduction of ROS develops or the body fails to eliminate ROS in excess, oxidative stress arises, during which ROS accumulate and damage cells and tissues. Besides their noxious effects, accumulating data have shown that controlled and adequate ROS concentrations exert physiologic functions. Different studies have confirmed the presence of ROS and the transcripts of the various antioxidant enzymes in the female reproductive tract. When ROS production overwhelms antioxidant defences, oxidative stress occurs, which may deeply threaten the anatomical and functional integrity of the genital tract. This review addresses the main physiological and pathological roles exerted by ROS and their scavenging systems in several processes involved in the main physiological functions of the female reproductive tract of both women and domestic animals. Particularly, the involvement of the oxidant system in several reproductive processes is investigated, such as follicular development, ovarian steroidogenesis, ovulation, corpus luteum formation and function, luteolysis, germ cell function, maintenance of pregnancy and beginning of parturition.

Effects of rosiglitazone, a PPAR-gamma agonist, on the contractility of bovine uterus in vitro.

Rosiglitazone is a drug used in human medicine for treating type II diabetes mellitus. It activates Peroxisome Proliferators-Activated Receptors gamma (PPAR-gamma), which regulate energetic metabolism. We aimed to evaluate the effects of rosiglitazone on bovine myometrial contractility in vitro. Myometrial strips were collected from uteri of cows in estrus, diestrus, and pregnancy. Contractions were recorded using an isometric force transducer. After the equilibration period, rosiglitazone (1 x 10(-6)) was added to the bath. Its effects on the amplitude and frequency of spontaneous contractions were evaluated. Data were analyzed using an ANOVA and Student's t-test and were considered significant at P < 0.05. Rosiglitazone increased the mean amplitude during estrus (P < 0.01), diestrus (P < 0.05), and pregnancy (P < 0.01); the frequency of contractions in both pregnancy (P < 0.05) and diestrus (P < 0.05) increased as well. These effects are likely due, in our opinion, to an increase in intracellular calcium concentrations, as well as enhanced uptake of glucose from the Krebs' solution. The differences observed according in the different phases are ascribable to the different hormonal milieu. Our study indicates that rosiglitazone affects bovine myometrial contractility. It may be considered a starting point for further studies on the application of this drug in veterinary obstetrics.