Enhanced tyrosine phosphorylation of striatal NMDA receptor subunits: effect of dopaminergic denervation and l-DOPA administration

Sensitization of striatal N-methyl- -aspartate receptors (NMDAR) has been linked to events leading to the motor response changes associated with the administration of dopaminomimetics to parkinsonian animals and patients. To determine whether tyrosine phosphorylation of NMDAR subunits contributes to the apparent long-term enhancement in synaptic efficacy of these receptors, we examined the effect of unilateral nigrostriatal dopamine system ablation with 6-hydroxydopamine followed by twice-daily treatment with -DOPA on the phosphorylation state of rat striatal NR2A and NR2B subunits. Three weeks of intermittent -DOPA administration produced a shortening in the duration of the rotational response to dopaminergic challenge and other changes mimicking those occurring in patients with Parkinson's disease. Concurrently, tyrosine phosphorylation of NR2A and especially of NR2B subunits increased ipsilateral to the lesion (20±5% and 46±7% of intact striatum, respectively; p<0.01) without attendant changes in subunit protein levels. Selective blockade of NR2B subunits with ACEA 10-1244, but not of NR2A subunits with MDL 100,453, reversed the -DOPA-induced response alterations. The intrastriatal injection of a tyrosine kinase inhibitor, genistein, at a dose (2.0 μg) that normalized the response shortening, attenuated the NR2A and NR2B phosphorylation increase by about 12% and 24%, respectively (p<0.01). Taken together, these results suggest that augmented tyrosine phosphorylation of NR2B subunits, alone or in combination with the smaller rise in NR2A subunit phosphorylation, contributes to the apparent enhancement in striatal NMDAR sensitivity and thus to the plastic alterations in dopaminergic responses in -DOPA-treated parkinsonian rats.     

Tyrosine kinase inhibition reduces i f in rabbit sinoatrial node myocytes

 We studied pacemaker current (i _f), the inward current activated by hyperpolarization in rabbit sinoatrial (SA) node myocytes, with the permeabilized-patch-clamp technique. The tyrosine kinase inhibitors genistein (50 μM) or herbimycin A (35 μM) reduced the amplitude of i _f in response to step hyperpolarizations in the diastolic range of potentials. A two-step voltage-clamp protocol revealed that the reduction in i _f is due to a decrease in maximal i _f conductance. The observed effects are due to tyrosine kinase inhibition since an inactive analog of genistein did not reduce i _f. To further examine the mechanism of action, we added 2 mM chlorophenylthio cAMP (CPTcAMP, a membrane-permeant cAMP analog) to the bathing Tyrode, which increased i _f. Genistein still reduced i _f in the presence of CPTcAMP. This suggests that the pathway mediating the actions of tyrosine kinase inhibition on i _f is independent of cAMP- or protein-kinase-A-mediated phosphorylation. Received: 28 January 1997 / Received after revision: 21 April 1997 / Accepted: 22 April 1997     

Direct action of genistein on CFTR

 Human cystic fibrosis transmembrane conductance regulator (CFTR) chloride channels were expressed in oocytes from Xenopus laevis after injection of CFTR cRNA and studied with the two-electrode voltage-clamp and the giant patch techniques. The tyrosine kinase inhibitor genistein alone activated a small chloride current in whole oocytes expressing CFTR and substantially increased the chloride current obtained upon stimulation with forskolin and isobutyl methylxanthine (IBMX). In giant excised patches, genistein was unable to open protein-kinase-A-phosphorylated CFTR channels in the absence of ATP, but increased the ATP-induced CFTR channel currents by a factor of 3.8 ± 1.7. This genistein-mediated potentiation in excised patches is independent of protein phosphatase activity, as it is readily reversible, even after complete inhibition of protein kinase A activity. Involvement of protein tyrosine kinases also seems unlikely, because this effect of genistein is not antagonized by high concentrations of the tyrosine phosphatase inhibitor ortho-vanadate. We, therefore, propose a direct interaction of genistein with CFTR, probably at a nucleotide binding site, which leads to a higher open probability. Received: 10 March 1997 / Received after revision and accepted: 22 April 1997     

ATRA联合Genistein对肺癌细胞凋亡及ICAM-1表达的影响

目的 探讨ATRA联合Genistein对A549细胞凋亡及细胞间黏附分子-1（ICAM-1）表达的影响。方法采用ATRA、Genistein单药及两者联合处理人肺腺癌细胞株A549，观察A549细胞生长情况并采用MTT法检测A549细胞的增殖抑制率，运用TUNEL法检测细胞凋亡，流式细胞仪检测细胞表面ICAM-1的表达。结果A549肺癌细胞经ATRA、Genistein及两者联合处理后，细胞增殖明显受抑制，凋亡指数明显提高，ICAM-1表达明显下调；其中以两者联合用药最为显著。结论ATRA联合Genistein能协同抑制A549细胞的增殖、促进细胞的凋亡，并可能下调ICAM-1的表达，进而降低肺癌细胞转移的潜能。     

金雀异黄酮对去卵巢大鼠脑抗氧化作用的影响

目的研究金雀异黄酮对去卵巢大鼠大脑抗氧化作用的影响,为使用植物雌激素防治女性更年期后老年性痴呆提供依据。方法40只3月龄雌性SD大鼠,随机分为假手术组、去卵巢对照组、金雀异黄酮组和苯甲酸雌二醇组,给予相应手术和治疗。术后6周分析大鼠额叶、颞叶、海马和基底前脑的SOD和MDA值。结果假手术组颞叶和海马的SOD值低于基底前脑(P<0.05);额叶和颞叶的MDA值高于海马和基底前脑(P<0.05);去卵巢对照组基底前脑的SOD值显著低于假手术组、金雀异黄酮组和苯甲酸雌二醇组(P<0.05),MDA值显著高于假手术组、金雀异黄酮组和苯甲酸雌二醇组(P<0.05);假手术组、金雀异黄酮组及苯甲酸雌二醇组之间SOD值和MDA值差异无统计学意义(P>0.05)。结论去卵巢对照组大鼠基底前脑抗氧化能力显著降低,氧化损伤程度显著升高,金雀异黄酮替代治疗可增加去卵巢大鼠基底前脑的抗氧化能力,降低基底前脑的氧化损伤,可用于女性更年期后老年性痴呆的防治。     

Modulation of Isoflavones on Bone—nodule Formation in Rat Calvaria Osteoblasts in vitro

Objective:to observe the effects of two main isoflavones,daidzein and genistein on the bone-nodule formation in rat calvaria osteoblasts in vitro.Methods:Osteoblasts obtained from newborn Sprague-dawley rat calvarias were cultured for several generations.The second generation cells were cultured in Minimum Essential Medium supplemenmted with ascorbic acid and Na-beta-glycerophosphate for several days,in the presence of daidzein and genistein,with or without the estrogen receptor antagonist ICI 182780.Number of nodules was counted at the end of the incubation period(day 20) by staining with Alizarin Red S calcium stain.The release of osteocalcin,as a marker of osteoblast activity,was also determined on day 7 and 12 during the incubation period.Results:compared with the control,the numbers of nodules were both increased by incubation with daidzin and genistein,17β-estradiol was used as a positive control and proved to be a more effective inducer of the increase in bone-nodules formation than daidzein and genisterin.The release of osteocalcin into culture media was also increased in the presence of daidzein and genistein,as well as 17β-estradiol on day 7 and day 12(day 12 were higher).The estrogen receptor antagonist ICI 182780 completely blocked the genistein-and 17β0estradiol-induced increase of nodule numbers and osteocalcin release in osteoblasts.Howerver,the effects induced by daidzein could not be inhibited by ICI 182780.Conclusion:These findings suggest that geinistein can stimulate bone-nodule formation and increase the release of osteocalcin in rat osteoblasts.The effects,like those induced by 17β-estradiol,are mediated by the estrogen receptor dependent pathway,Daidzin also can stimulate bone-nodule formation and increase the release of osteocalcin in rat osteoblasts,but it is not,at least not merely,mediated by the estrogen receptor dependent pathway.     

植物雌激素两种单体对子宫内膜腺上皮细胞作用的比较

目的 探讨植物雌激素两种单体在浓度5～80μmol／L对人子宫内膜腺上皮细胞增殖的影响。方法 2003年8～12月应用胶原酶阶梯消化法，原代培养人子宫内膜腺上皮细胞，用MTT方法观察植物雌激素的主要成分金雀黄素和大豆甙元对细胞体外增殖的影响。结果 低浓度的大豆甙元能促进子宫内膜腺上皮细胞轻度生长．随浓度的增加其作用明显，但当浓度达到40μmol／L，抑制细胞生长；不同浓度的金雀黄素均抑制子宫内膜腺上皮细胞的增殖。结论 植物雌激素两种单体对人子宫内膜腺上皮细胞的作用是明显不同的，提示在应用植物雌激素时要考虑不同成分的差别?     

Genistein对人肝癌细胞SMMC-7721的抗增殖作用

目的：探讨Genistein对人肝癌细胞SMMC-7721的抑制增殖作用及其机理。方法：采用MTT法测定Genistein在不同浓度、不同时间对SMMC-7721细胞抑制增值的效应；流式细胞术分析细胞周剧期分布及凋亡率；透视电镜观察细胞超微结构改变；免疫细胞化学法检测细胞凋亡相关蛋白的表达。结果：Genistein可抑制SMMC-7721细胞的增殖，其抑制率与药物浓度和作用时间呈依赖关系；72h的IC50为29．0760μmol／L；流式细胞仪分析证实Genistein能使SMMC-7721细胞聚积在G2／M期，凋亡率为8．81％（P〈0．05）；透视电镜观察发现Genistein能诱导细胞凋亡；免疫细胞化学法显示：Bax、Fas、Myc、iNOS、NF—kB表达增加，Bcl-2、MTP53表达减低、结论：Genistein在体外可抑制SMMC-7721细胞增殖作用，是通过细胞阻滞在G2／M期和上调Bax、Fas、Myc、iNOS、NF—kB的表达及下调Bcl-2、MTP53表达诱导的细胞凋亡.     

Soy but not bisphenol A (BPA) induces hallmarks of polycystic ovary syndrome (PCOS) and related metabolic co-morbidities in rats

Polycystic ovarian syndrome (PCOS) is the most common female endocrine disorder with a prevalence as high as 8–15% depending on ethnicity and the diagnostic criteria employed. The basic pathophysiology and mode of inheritance remain unclear, but environmental factors such as diet, stress and chemical exposures are thought to be contributory. Developmental exposure to endocrine disrupting compounds (EDCs) have been hypothesized to exacerbate risk, in part because PCOS hallmarks and associated metabolic co-morbidities can be reliably induced in animal models by perinatal androgen exposure. Here we show that lifetime exposure to a soy diet, containing endocrine active phytoestrogens, but not developmental exposure (gestational day 6–lactational day 40) to the endocrine disrupting monomer bisphenol A (BPA), can induce key features of PCOS in the rat; results which support the hypothesis that hormonally active diets may contribute to risk when consumed throughout gestation and post-natal life.     

Genistein as antioxidant and antibrowning agents in in vivo and in vitro: A review

Genistein is a phytoestrogen with diverse biological activities. It is a potent antioxidant and antibrowning agent in in vivo and in vitro. Genistein acts as a preventative and therapeutic effects for cancers, postmenopausal syndrome, osteoporosis and cardiovascular diseases in animals and humans. Gensitein possesses cancer related enzyme-inhibitory effect and substantially inhibits skin carcinogenesis and cutaneous aging induced by ultraviolet (UV) light in mice and photodamage in humans. Two-stage skin carcinogenesis showed genistein exhibited a moderate inhibition of ornithine decarboxylase activity through blockage of DNA adducts formation. The anticancer, anti-inflammatory, cardio-protective and enzyme-inhibitory effects of genistein might be related to their antioxidant activities. Genistein also altered the Maillard reaction pathway by trapping the advanced glycation end products (AGEs) both in biological and protein-lactose suspensions. As a result, soy isoflavone can be used to enrich or fortify different types of food products.