ABSTRACT
Objective To determine the effects of genistein and daidzein on the proliferation and survival of the hippocampal neural cells and underlying mechanism. Methods H19-7/IGF-IR neural cell line was cultured in phenol red free DMEM absented of serum for 72h. Genistein, daidzein or 17β-estradiol was added to the culture at various concentrations. Their proliferation and protective effects on the neuronal cells were determined by BrdU and MTT assay respectively. The effect of phytoestrogens on cell cycle regulation was determined using flow cytometry. The effects of the soy isoflavones on brain-derived neurotrophic factor (BDNF) expression were determined by ELISA and RT-PCR respectively. Results It was observed that, with 72h of treatment, 20nM and 200 nM 17B-estradiol significantly promoted the neuronal cell proliferation at 33% and 36% ;20nM and 200nM genistein significantly promoted the neuronal cell proliferation at 15% and 13% ; 200nM daidzein significantly promoted the neuronal cell proliferation at 11% compared to the control (P＜0.05). Genistein and daidzein induced an significantly increase in the S phase arrest at (17.64 ± 0.43) % and (19.48 ± 1.01) % compared to the control (P ＜ 0. 05). Moreover, genistein and daidzein significantly increased the expression of mature BDNF and BDNF mRNA level (P＜0.05). The effect of genistein and daidzein on hippocampal neuronal cell proliferation was blocked by K252a, selective inhibitor of tyrosine kinase receptors. Conclusion Genistein and daidzein improved hippocampal neuronal cell proliferation and viability in vitro. The effects might be mediated by increasing in BDNF expression.
ABSTRACT
<p><b>OBJECTIVE</b>To investigate the expression regulation of thyrotrophin-releasing hormone (TRH) and TRH receptor (TRH-R), and their role in the development of rat testis.</p><p><b>METHODS</b>Oligonucleotide primers were designed from the sequences of rat hypothalamus prepro TRH (ppTRH) and pituitary TRH-R cDNA for reverse transcription polymerase chain reaction (RT-PCR). Specific fragments of ppTRH and TRH-R cDNA were cloned and sequenced. Expression plasmids containing ppTRH and TRH-R genes were then constructed, and expression was found in E. coli DH5-alpha. ppTRH and TRH-R mRNA in the testis was quantitated in RNA samples prepared from rats at different developmental stages by real time quantitative RT-PCR.</p><p><b>RESULTS</b>The quantitative analyses demonstrated that no ppTRH and TRH mRNA could be detected at the earliest stage (day 8). ppTRH and TRH mRNA signals were detected on day 15 and increased progressively on days 20, 35, 60 and 90.</p><p><b>CONCLUSION</b>Our results suggest that rat testis could specifically express TRH and TRH-R, and the transcriptions of ppTRH and TRH-R genes in the rat testis were development-dependent. The acquirement of expressed products for ppTRH and TRH-R can be used for further research on the physiological significance of TRH and TRH-R expression in rat testis.</p>