Análise do efeito da quercetina sobre a passagem da glicose do líquido cefalorraquidiano para o cérebro de ratas ovariectomizadas submetidas ao tratamento com tamoxifeno

Abstract

Tamoxifen is classified as selective estrogen receptor modulador (SERM), being used in the treatment and prevention of breast cancer. Although presents many side effects, tamoxifen is a therapy of choice for the treatment of breast cancer in the postmenopausal period. The quercetin, a flavonoid with antioxidant potent effect, has benefits on the adverse effects caused by tamoxifen, especially those related to lipoperoxidation. The study of the neuroprotective effect of quercetin on brain bioenergetics is important for the recognition of the mechanisms involved. Thus, the objective of this work was to analyze the tamoxifen effects on glucose metabolism in the brain and the influence of quercetin coadministered with tamoxifen on passage of glucose from the cerebrospinal fluid to the brain of ovariectomized rats submitted to tamoxifen treatment. For this, bilaterally ovariectomized rats were separated into groups and treated with canola oil (1.0 mL.Kg-1) tamoxifen (5 mg.Kg-1), quercetin (22.5 mg.Kg-1) and the coadministration of tamoxifen (5 mg.Kg-1) plus quercetin (22.5 mg.Kg-1), orally for 14 days. The blood, cerebrospinal fluid, cerebellum, cortex, and hippocampus were collected for glucose lactate and pyruvate dosage as well copper and ceruloplasmin. It was observed that tamoxifen increased blood glucose levels and that co-administration with quercetin brought these levels close to the values of the control group. In cerebrospinal fluid, the quercetin administration didn´t influence glucose levels and in the different brain regions, both quercetin alone such as coadministration with tamoxifen significantly decreased glucose values when compared to the group that received only tamoxifen. The coadministration of quercetin with tamoxifen was shown be effective not only in maintenance glycemic levels but also in cerebral glucose levels.