Evaluating the neuroprotective effects of fermented rooibos herbal tea in Wistar rats exposed to bisphenol-A during gestation and lactation

Abstract

Exposure to endocrine-disrupting chemicals as bisphenol A (BPA) during gestation and early postnatal life is known to disrupt normal developmental processes and alter the body’s endocrine system leading to deleterious effects in the developing central nervous system (CNS). BPA is an industrial synthetic chemical commonly used in the production of a range of polymers and consumer products, despite concerns about its safety. There is therefore the need to protect the developing CNS from potential damage through the administration of neuroprotective agents. Most medicinal plants are reported to possess significant protective potential against tissue damage through different mechanisms that prevent cell death, oxidative stress, inflammation, immunodeficiency, etc. In this study, the protective effects of fermented rooibos (Aspalathus linearis) tea against the deleterious effects of BPA were investigated. Rooibos is a herbal beverage indigenous to South Africa with widely acclaimed health benefits often linked to the bioactivity of its polyphenolic compounds, especially aspalathin. The anti-allergic, cardiovascular, antioxidant and neuroprotective effects of this herb have been previously reported hence, the present study aims to investigate if regular consumption of rooibos tea during pregnancy and lactation could protect the developing brain from the deleterious effects of BPA in a Wistar rat model. A total of 40 three-month old adult female pregnant dams, with an average weight of 250g, were divided into four groups (n=10). Group 1 control rats received 9% normal saline ad libitum; group 2 rats received 400μg/kg/day BPA only; group 3 rats received 20% fermented rooibos tea as well as 400μg/kg/day BPA, while group 4 rats received ad libitum 20% fermented rooibos tea only. Offspring rats were housed in the same cages as the dams and only separated after weaning on postnatal day (PND) 21. Neurobehavioural assessment using the open field test was done on postnatal day (PND) 42 after which the final body masses were taken before the rats were decapitated under deep anaesthesia, and the desired CNS parts carefully dissected out and processed for histological, biochemical and immunohistochemical studies. The results obtained showed that there was significant impairment of neurobehavioural activity, decreased cerebral and cerebellar antioxidant enzyme activity, reduced hippocampal CA1 length, significant loss of cerebellar Purkinje cells and significant astrocyte activation demonstrated by increased glial fibrillary acidic protein (GFAP) activity in experimental rats exposed to BPA only. However, co-administration of rooibos tea significantly attenuated the BPA-induced distortions. Taken together, these findings suggest that rooibos could be a potent neuroprotective agent against BPA-induced structural, functional and biochemical alterations in the developing CNS.