Efeitos da suplementação com o extrato do caroço do açaí (Euterpe oleracea Mart.) sobre os parâmetros metabólicos na menopausa experimental

Abstract

Menopause is characterized by the cessation of reproductive function and a decrease in ovarian sex hormone production, causing various symptoms, including metabolic changes. Data in the literature indicate the protective role of estrogen and the increased risk of developing metabolic diseases in postmenopausal women. Although hormone replacement therapy is clinically used, there are some contraindications, which make this treatment restricted for some individuals. Therefore, natural compounds are being investigated as alternative therapies. Therefore, the objective of the present study was to evaluate the effects of açaí seed extract (ASE) on metabolic parameters associated with experimental menopause. Experimental menopause was induced by bilateral ovariectomy (OVX) in Sprague-Dawley rats (90 days of age) under isoflurane anesthesia. Sham rats served as controls. One month after surgery, ASE supplementation (200 mg/kg/day by intragastric gavage) was initiated and continued for 8 weeks. Four experimental groups were used: Sham, Sham+ASE, OVX, and OVX+ASE. Food and water intake were assessed three times a week. Body weight was measured weekly. Blood glucose levels were measured on the day of surgery and in the last week of the protocol. Body composition was assessed by nuclear magnetic resonance imaging at three time points: 30 days post-surgery, and 30 and 60 days of supplementation with the extract. After 12 weeks of protocol, the rats were euthanized to obtain plasma, uterus, adipose tissue, and liver samples. Plasma lipid profiles and levels of 17β-estradiol, leptin, T3, T4, TSH, and hepatic transaminases were evaluated. Liver, retroperitoneal white adipose tissue (RAWT), and brown adipose tissue (BAT) samples were fixed for histological analysis. BAT slides were used for immunohistochemistry to evaluate immunostaining for UCP-1, PGC1-α, and 8-isoprostane. Pro- and antioxidant assays were measured in liver homogenates, RAWT, and BAT. Steatosis, ballooning, and fibrosis in liver tissue were also assessed. Ovariectomy reduced 17β-estradiol levels and led to uterine atrophy, validating the surgical protocol. ASE supplementation prevented weight gain and body composition changes, and restored plasma and liver leptin, T3, T4, cholesterol, and triglyceride levels. Furthermore, the extract showed beneficial effects in preventing increased Gamma-GT levels, as well as steatosis, ballooning, and fibrosis. In adipose tissue, ASE improved adipocyte hypertrophy in TABR, although it did not modify morphology in BAT. However, UCP-1 immunostaining was restored, while 8-isoprostane immunostaining was attenuated in the OVX + ASE group, suggesting an effect of the extract on oxidative damage and thermogenesis. Pro- and antioxidant assays in homogenates of the three tissues demonstrated the antioxidant effect of ASE in ovariectomized rats. Furthermore, TNF-α and IL-6 levels in adipose tissue were reduced with the use of the extract. The data suggest a great potential for ASE in preventing metabolic changes resulting from experimental menopause, which is associated with its antioxidant and anti-inflammatory action.