Endocrine profile of the VCD-induced perimenopausal model rat.

During the transition to menopause, women experience a variety of physical and psychological symptoms that are directly or indirectly linked to changes in hormone secretion. Establishing animal models with intact ovaries is essential for understanding these interactions and finding new therapeutic targets. In this study, we assessed the endocrine profile, as well as the estrous cycle, in the 4-vinylcyclohexene diepoxide (VCD)-induced follicular depletion rat model in 10-day intervals over 1 month to accurately establish the best period for studies of the transition period. Twenty-eight-day-old female rats were injected daily with VCD or oil s.c. for 15 days and euthanized in the diestrus phase approximately 70, 80, 90 and 100 days after the onset of treatment. The percentage of rats showing irregular cycles and the plasma level of FSH increased only in the 100-day VCD group. Plasma anti-Müllerian hormone (AMH) and progesterone were lower in all VCD groups compared to control groups, while estradiol remained unchanged or higher. As in control groups, dihydrotestosterone (DHT) progressively decreased in the 70-90-day VCD groups; however, it was followed by a sharp increase only in the 100-day VCD group. No changes were found in plasma corticosterone, prolactin, thyroid hormones or luteinizing hormone. Based on the estrous cycle and endocrine profile, we conclude that 1) the time window from 70 to 100 days is suitable to study a perimenopause-like state in this model, and 2) regular cycles with low progesterone and AMH and normal FSH can be used as markers of the early/mid-transition period, whereas irregular cycles associated with higher FSH and DHT can be used as markers of the late transition period to estropause.

Endocrine disruptors and dental materials: health implications associated with their use in Brazil.

This study analyzes international historical trends in the use of different types of materials in dental practice. The author describes the chemical properties of their ingredients and the potential and observed adverse effects in patients and dental technicians resulting from clinical or occupational exposure to various metals like beryllium, used to produce metal alloys. The growing use of various products (resin cements, ionomer cements, aesthetic restorative materials, resins, endodontal cements, and others) based on the compound bisphenol-A, whose chemical structure is similar to that of estrogen. Considering the demographic and contemporary work force characteristics of those involved in dental practice in the Brazil, the study highlights the possible effect of the use of these materials in both male and female patients and all age strata, as well as in health professionals with occupational exposure to products containing bisphenol-A.