Effects of black cohosh on estrogen biosynthesis in hippocampus of non-human primates ex vivo in vitro and in human neuroblastoma cells in vitro

Abstract

Background: Estrogens have neuroprotective properties. The aim of the study was to assess the impact of an isopropanolic extract of Cimicifuga racemosa (iCR), 17s-estradiol (E2), testosterone (T) and Tibolone's 3alpha-OH metabolite (Org4094) on local estrogen formation in hippocampus tissue from non-human primates ex vivo in vitro and human neuroblastoma cells (SH-SY5Y) in vitro. Methods: SH-SY5Y cells were incubated in RPMI 1640 medium containing 5 % steroid-depleted fetal calf serum for 3 days, and subsequently incubated in absence or presence of iCR at 10 mug/ml (n = 5) and 1 mug/ml (n = 5), E2 at 10-8 M (n = 5), and 10-6 M (n = 5), or T at 10-8 M (n = 5), and 10-6 M (n = 5), respectively, at 37 degreeC for either 24 h or directly in cell extracts. Hippocampus tissue from healthy female cynomolgus macaques (n = 14) was homogenized and treated with iCR, E2 and Org4049 accordingly. STS activity was evaluated by incubating homogenized brain cells and tissue with [3H]-estrone sulfate and separating the products estrone (E1) and E2 by thin layer chromatography. STS activity was expressed as total estrogen formation (E1 + E2) fmol/mg of protein/min. Statistical comparisons were made using unpaired T-Test for comparing two sets of data and ANOVA to compare many groups at once. A p value < 0.05 was considered to be significant different. Results: Basal total estrogen formation was significantly higher in proliferative SH-SY5Y cells (1350.06 +/- 109 E1 + E2 fmol/mg of protein/min) compared to hippocampus tissue (37.83 +/- 3.9 E1 + E2 fmol/mg of protein/min; p < 0.01). ICR exerted a bidirectional action with an immediate strong inhibitory effect being followed by a stimulation of STS activity (85 % increase). E2 had a bidirectional dose-dependent long-term effect on STS activity (-23 % reduction and 18 % increase). T and Org4094 had an immediate strong inhibitory effect on STS activity that further maintained with 24 h T treatment (30 % decrease). Conclusions: Local estrogen formation within brain cells and tissue may be modulated by black cohosh, 17s-estradiol, testosterone, and Tibolone's 3alpha-OH metabolite, respectively. The clinical implication of this finding has to be elucidated. Copyright © 2016, Stute et al.