Obesity constitutes a health problem of increasing worldwide prevalence. Among the health detriments caused by obesity, reproduction is disrupted. However, the mechanisms involved in this disruption are not fully understood. Animals fed a cafeteria diet constitute the model for the study of obesity that most closely reflects Western diet habits. The aims of this study were to evaluate whether a cafeteria diet affects ovarian function and to contribute to the understanding of the mechanisms involved. For that purpose, 22-day-old female Wistar rats were fed ad libitum with a standard diet (control group; n = 20) or cafeteria diet (CAF group; n = 20). The cafeteria diet induced obesity and hyperglycaemia, without altering serum triglycerides, cholesterol or C-reactive protein concentrations. This diet also altered ovarian function: the rats showed prolonged dioestrous phases, decreased serum oestradiol concentrations and increased number of antral atretic follicles. Moreover, follicular cysts were detected in the CAF group, concomitantly with a decrease in the number of anti-Müllerian hormone immunoreactive pre-antral follicles and COX-2-positive antral and pre-ovulatory follicles. The authors conclude that a cafeteria diet reduces ovarian reserve, induces the presence of follicular cysts and disturbs the ovulatory process, leading to the delayed pregnancy observed in these animals.
BackgroundIn assisted reproduction cycles, gonadotropins are administered to obtain a greater number of oocytes. A majority of patients do not have an adverse response; however, approximately 3-6% develop ovarian hyperstimulation syndrome (OHSS). Metformin reduces the risk of OHSS but little is known about the possible effects and mechanisms of action involved.ObjectiveTo evaluate whether metformin attenuates some of the ovarian adverse effects caused by OHSS and to study the mechanisms involved.Material and methodsA rat OHSS model was used to investigate the effects of metformin administration. Ovarian histology and follicle counting were performed in ovarian sections stained with Masson trichrome. Vascular permeability was measured by the release of intravenously injected Evans Blue dye (EB). VEGF levels were measured by commercially immunosorbent assay kit. COX-2 protein expression was evaluated by western blot and NOS levels were analyses by immunohistochemistry.ResultsAnimals of the OHSS group showed similar physiopathology characteristics to the human syndrome: increased body weight, elevated progesterone and estradiol levels (P<0.001), increased number of corpora lutea (P<0.001), higher ovarian VEGF levels and vascular permeability (P<0.001 and P<0.01); and treatment with metformin prevented this effect (OHSS+M group; P<0.05). The vasoactive factors: COX-2 and NOS were increased in the ovaries of the OHSS group (P<0.05 and P<0.01) and metformin normalized their expression (P<0.05); suggesting that metformin has a role preventing the increased in vascular permeability caused by the syndrome.ConclusionMetformin has a beneficial effect preventing OHSS by reducing the increase in: body weight, circulating progesterone and estradiol and vascular permeability. These effects of metformin are mediated by inhibiting the increased of the vasoactive molecules: VEGF, COX-2 and partially NOS. Molecules that are increased in OHSS and are responsible for a variety of the symptoms related to OHSS.
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