Mechanism of Reproductive Effect of Acetyl acetate‐methanol Fraction of Adansonia digitata (Linn) Root Bark Extract in Female Wistar Rats

Abstract

The aim of this work was to identify the exclusive components of Acetyl acetate‐methanol fraction (AAMF) of Adansonia digitata (Linn) root bark extract and to elucidate its mechanism of action in modulating hormone signaling. Gas chromatography and Mass spectrometry was done to identify the compounds present in fractions of A. digitata (Linn) root bark extract. Thirty female Wistar rats had their estrous cycles synchronized and were randomly distributed into three groups of ten rats each. Each group received 0, 150, and 300mg/kg body weight of AAMF per os from the day observed as proestrus by vaginal cytology to day‐seven. On day‐one, day‐four, day‐five, day‐six and day‐seven, blood was collected from rats in each group. Blood collected was analyzed for estrogen, progesterone and follicle stimulating hormone levels. Uterus and ovary were processed for histopathology and immunohistochemistry to study the regulation of estrogen and progesterone receptor proteins. Where a receptor protein was regulated, further investigation was done to determine its effect on the gene expression of that receptor in endometrial stromal cells through RNA extraction, OneStep reverse transcription‐pCR amplification, Agarose gel electrophoresis and quantification of pCR product. Results showed that AAMF uniquely contained 15.25% of oleic acid and caused mass atresia of antral follicles at proestrus. AAMF treated rats had significantly (p<0.05) lowered serum estradiol levels at proestrus when compared to control rats and had up‐regulated estrogen receptor beta proteins in endometrium and downregulated estrogen receptor alpha (ERα) gene expression in endometrial cells. It was concluded that the oleic acid component of AAMF may have lowered estrogen level by inhibiting aromatase and hydroxysteroid 17 beta dehydrogenase enzyme activities in estrogen steroidogenesis. Also, oleic acid may have induced overexpression of Tumour Suppressor Factor (P53) which promotes follicular apoptosis and indirectly downregulates ERα when p53 activities become exacerbated. It is recommended that AAMF be investigated as a possible therapy for some ERα sensitive clinical conditions like cancer.