雌激素及植物雌激素对去卵巢大鼠乳腺组织形态和ERα亚型表达的影响

目的探讨雌激素及植物雌激素对去卵巢大鼠乳腺组织形态和ERα亚型表达的影响,并比较雌激素和植物雌激素作用的异同。方法48只Wistar大鼠随机分为8组,分别为假手术组(Sham)、去卵巢组(Ovx)、17β-雌二醇组(Ovx+Est)、17-β雌二醇+黄体酮组(Ovx+Est+Pro)、黄体酮组(Ovx+Pro)、染料木素组(Ovx+Gen)、白黎芦醇组(Ovx+Res)、根皮素组(Ovx+Phl)。对应组给药21d后处死,取乳腺组织,用蛋白免疫印迹法观察各组大鼠乳腺ERα的表达、并利用免疫组化对其形态学变化进行观察。结果乳腺组织中的ERα主要位于乳腺导管上皮细胞的胞质和胞核内。ERα在8组中均可表达,但表达量却不同。Sham与Ovx比较,Ovx组ERα表达上调(P<0·05);Ovx与Ovx+Est、Ovx+Pro、Ovx+Gen、Ovx+Res、Ovx+Phl比较,后5组ERα表达均下调(P<0·01);Ovx与Ovx+Est+Pro比较则差异无显著性(P>0·05);大鼠卵巢切除后,乳腺明显萎缩。卵巢切除大鼠皮下分别注射Gen和Phl后,乳腺结构仍呈现出卵巢切除后的表现。皮下注射Res乳腺腺泡及其上皮细胞有不同程度的增生。皮下注射Est或Est合并Pro后,乳腺组织密度增加,乳腺上皮细胞明显增生。结论植物雌激素Gen、Phl和Res与雌激素相似,可以下调去卵巢切除大鼠乳腺组织ERα的表达;Res还可促进去卵巢切除大鼠乳腺上皮细胞增生,但作用不如雌激素强。     

两种雌激素对去卵巢大鼠子宫内膜的影响

目的：探讨戊酸雌二醇和炔雌醇对去卵巢大鼠子宫内膜的作用,为绝经后妇女雌激素补充治疗提供理论依据。方法选用3月龄雌性Sprague-Dawley（ SD）大鼠40只,实验分为Sham组（假手术组）、Ovx组（去卵巢组）、A组（炔雌醇组）、B组（戊酸雌二醇组）。除Sham组外,其余各组均切除双侧卵巢建立骨质疏松动物模型。去势后4周开始A组炔雌醇（0.1 mg·kg-1·d-1）、B组戊酸雌二醇（0.4 mg·kg-1·d-1）灌胃。4组均在90 d对大鼠称重,取大鼠子宫进行称重,子宫内膜行病理切片检查。结果用药12周后各组间大鼠体重无统计学差异。 B 组子宫湿重及子宫指数明显低于A组（P〈0.05）,与Ovx组比较,无显著性差异（P〉0.05）。但A组子宫湿重及子宫指数明显升高,与Ovx组比较差异有统计学意义（P〈0.05）。两组用药组与Ovx组相比均显示子宫内膜增厚,上层单层柱状,肌层肌纤维排列规则一致,浆膜层光滑。 B组可见内膜增厚,但低于A组,两组均未见内膜增生过长、核异性和非典型增生样改变。结论戊酸雌二醇与炔雌醇用于绝经后雌激素补充治疗,虽对子宫内膜均有生长作用,但均未见过度生长及异型性改变。     

雌激素对大鼠心内神经节血管内皮生长因子表达的影响

目的:用免疫组织化学方法观察成年雌性大鼠,卵巢摘除组大鼠,卵巢摘除后17beta雌二醇肌肉注射组大鼠的心内神经节血管内皮生长因子(VEGF)的表达及变化。方法:免疫组织化学染色。结果:①各组大鼠心内神经节均存在VEGF表达阳性神经细胞;②卵巢摘除组大鼠心内神经节VEGF阳性神经元明显减少,表达明显减弱(P<0.05)。结论:心内神经节细胞表达血管内皮生长因子(VEGF);雌激素可能影响心内神经节VEGF的表达。     

雌激素对血管平滑肌细胞凋亡的影响

目的 :观察雌激素对血管平滑肌细胞 (SMC)凋亡的影响。方法 :以大鼠为对象 ,观察正常对照组、去卵巢组及去卵巢 +雌二醇治疗组大鼠血管平滑肌细胞凋亡的关系。结果 :雌二醇治疗组血管平滑肌细胞凋亡较去卵巢组相比明显减少(P>0 .0 5 ) ,与正常对照组比较差别无显著性意义 (P >0 .0 5 )。结论 :雌二醇对血管平滑肌细胞的凋亡有抑制作用 ,可能是其预防动脉粥样硬化的机制     

当归芍药散对围绝经期模型大鼠子宫结构及雌激素受体表达的影响

目的:探讨当归芍药散(DSS)对围绝经期模型大鼠子宫结构及子宫腔上皮和基质中雌激素受体α(ERα)、雌激素受体β(ERβ)表达的影响。方法:将40只雌性SD大鼠随机分为假手术组(生理盐水)、模型组(生理盐水)和DSS低、中、高剂量组(1.94、3.87、7.44 g/kg),每组8只。除假手术组大鼠切除卵巢附近脂肪外,其余各组大鼠切除双侧卵巢以建立围绝经期模型。造模成功后,大鼠每天ig给药1次,连续8周。给药结束后,称定大鼠子宫湿质量,观察大鼠子宫形态和结构的变化,测定子宫腔上皮及基质中ERα、ERβ表达水平。结果:与假手术组比较,模型组大鼠子宫内膜柱状上皮呈低柱状,固有层、肌层与浆膜层均显著萎缩,基质细胞可见明显核固缩,子宫湿质量、宫腔面积、内膜厚度及腺体数量均显著减少(P<0.01),子宫腔上皮及基质中ERα、ERβ表达水平均显著降低(P<0.01)。与模型组比较,DSS各剂量组大鼠子宫内膜及固有层萎缩程度差异无统计学意义,但固有层内腺体丰富,子宫湿质量、宫腔面积、内膜厚度以及子宫腔上皮和基质中ERα表达水平差异均无统计学意义(P>0.05),但DSS中、高剂量组大鼠子宫腺体数量显著增加(P<0.01),DSS高剂量组大鼠子宫腔上皮及基质中ERβ表达水平显著升高(P<0.05或P<0.01)。结论:DSS对围绝经期模型大鼠子宫腺体萎缩症状的改善作用不明显,但可增加模型大鼠的腺体数量,这可能与提高子宫腔上皮及基质中ERβ表达水平有关。     

基于雌激素代谢调控的白藜芦醇对MNNG诱导子宫内膜癌变的抑制作用

目的考察白藜芦醇(Res)是否可能通过调控雌激素内稳态,进而抑制MNNG诱导小鼠子宫内膜的癌变。方法采用MNNG诱导EC小鼠模型,将小鼠随机分为Control组、Res组、MNNG组、MNNG+Res组。HE染色观察组织病理情况;q PCR检测Ccnd1、CK-19、Erbb2 mRNA的表达;LC-MS/MS检测小鼠血清和子宫中E_1、E_2、2-MeOE_1、4-MeOE_1、2-MeOE_2、4-MeOE_2、16α-OHE_1、2-OHE_1、4-OHE_1、2-OHE_2和4-OHE_2的含量。结果 MNNG组小鼠子宫内膜腺体增多、拥挤,局灶形成筛孔;MNNG+Res组小鼠子宫内膜腺体减少,趋于正常。与Control组相比,MNNG组Ccnd1、Erbb2mRNA表达明显升高,MNNG+Res组明显降低。MNNG组小鼠的血清和子宫组织中,2-MeOE_2、2-MeOE_1和4-MeOE_1含量明显下降,4-OHE_2含量明显增加,给予Res治疗后,血清中4-MeOE_1含量明显升高,子宫组织中2-MeOE_2和2-MeOE_1含量明显升高,4-OHE_2在血清和子宫组织中含量均明显降低。结论 EC小鼠体内雌激素内稳态失衡,Res可以上调雌激素代谢产物2-MeOE_2的含量,降低4-OHE_2的含量,抑制EC的发生发展。     

雌激素类药物对去卵巢大鼠认知功能的影响

目的 研究雌激素类药物对去卵巢大鼠认知功能的影响.方法 48只3～5个月龄雌性SD大鼠(清洁级)随机分为8组:假手术组、去卵巢(OVX)组、去卵巢后7-甲基异炔诺酮治疗组、去卵巢后雷洛昔芬治疗组、去卵巢后戊酸雌二醇治疗组、去卵巢后大豆异黄酮治疗组、去卵巢后半量戊酸雌二醇+半量大豆异黄酮治疗组、去卵巢后半量戊酸雌二醇+全量大豆异黄酮治疗组,每组6只,用药3个月.做Morris水迷宫实验测定大鼠逃避潜伏期及运动策略以判断认知功能的变化,同时用RT-PCR方法检测大鼠脑部海马淀粉样蛋白前体(APP)mRNA水平.结果 OVX组逃避潜伏期明显长于假手术组.所有用药组逃避潜伏期时间明显短于OVX组;且用药组高级运动策略次数明显多于OVX组.大鼠去卵巢后.海马APP mRNA表达量明显增高,用药组及假手术组APPmRNA表达低于OVX组.结论 雌激素类药物能抵抗去卵巢大鼠认知功能的损害,且可能是通过下调去卵巢大鼠海马APP mRNA表达水平发挥作用的.     

雌激素影响中枢神经递质代谢的实验研究

目的:研究卵巢切除(OVX)与雌激素替代(ER)对小鼠脑部海马区主要神经递质含量的影响。方法:实验动物分为对照组和卵巢切除组,卵巢切除组又分为不给药、给药7d和给药40 d的亚组。3个月月龄的雌性C5 7BL/6J小鼠(n=40 )摘除卵巢后至7个月月龄,于断头取标本前7d和40d分别给以雌激素(17β-雌二醇)。取小鼠脑海马分别测定Ch AT,NA,5 -HT的含量和活性。结果:卵巢切除未给雌激素小鼠子宫明显比对照组轻,(P<0.05)。而卵巢切除给雌激素7d及40 d亚组小鼠子宫重量比卵巢切除未用雌激素小鼠重(P<0.01)。卵巢切除组Ch AT活性和NA及5-HT递质含量与对照组比较显著下降(P<0.05 ) ;卵巢切除组给雌激素7d和40 d亚组并未增加Ch AT,NA和5 -HT的含量和活性。结论:雌激素去除降低了脑部的主要中枢神经递质的活性和含量,而且随时间的延长下降更明显,单纯的雌激素的替代对中枢神经递质的含量和活性并不能产生作用     

雌激素影响小鼠腹腔脂肪代谢作用机制的初步探讨

目的　研究雌激素在小鼠卵巢功能正常和卵巢切除时对腹腔脂肪代谢的影响。方法　3个月龄的雌性C5 7BL/6J小鼠40只,随机分4组,分别为正常对照,正常+雌激素,卵巢切除和卵巢切除+雌激素组,每组10只。小鼠摘除卵巢后饲养至7个月龄处死,检测腹腔脂肪重量。将2组给雌激素的小鼠于处死前60d分别皮下埋植控释雌激素(17β雌二醇)药丸(0.18mg/丸) ,以观察雌激素在卵巢功能正常和缺乏时对小鼠腹腔脂肪积聚的影响。结果　各组腹腔脂肪重量比较:卵巢切除组比正常对照组重,差别显著(P<0.05) ;正常+雌激素组与正常对照组比较无显著差别(P>0.05) ;卵巢切除+雌激素组比卵巢切除组轻,差别显著(P<0.05) ,与正常对照组比较无显著差别(P>0.05)。结论　卵巢切除明显导致腹腔脂肪积聚,而雌激素在卵巢切除时可以明显减少小鼠的腹腔脂肪积聚,但在卵巢功能正常时予以雌激素并不影响腹腔脂肪代谢,提示雌激素单独作用可以影响机体脂肪代谢,但其他性激素对雌激素的作用具有一定的影响     

雌激素类药物对去卵巢大鼠生殖内分泌免疫的影响

目的 研究雌激素类药物对去卵巢大鼠生殖内分泌免疫系统的影响.方法 48只3～5个月龄雌性SD大鼠随机均分为8组:(1)去卵巢(OVX)组;(2)假手术(S)组;(3)去卵巢后戊酸雌二醇治疗组(A);(4)去卵巢后半量戊酸雌二醇 半量大豆异黄酮治疗组(B);(5)去卵巢后半量戊酸雌二醇 全量大豆异黄酮治疗组(C);(6)去卵巢后大豆异黄酮治疗组(D);(7)去卵巢后雷洛昔芬治疗组(E);(8)去卵巢后7-甲基异炔诺酮治疗组(F).灌服药物12周后,处死动物前腹主动脉取血,处死时留取动物子宫、肾上腺、脾脏、胸腺等生殖内分泌免疫器官.分别检测各组血清雌二醇(E2)水平和T淋巴细胞亚群 CD3 、CD4 及CD4 /CD8 表达,以及各组生殖内分泌免疫器官的重量.结果 (1)OVX组E2水平较S组明显降低(P＜0.05);A、B、C组E2水平较OVX组明显增加(P＜0.01);A组E2水平较S组明显增加(P＜0.05).(2)OVX组CD3 、CD4 及CD4 /CD8 与S组比较明显降低(P＜0.01);各用药组CD3 、CD4 值均较OVX组明显增加(P＜0.05).(3)OVX组子宫、肾上腺、脾脏、胸腺的重量较S组明显降低(P＜0.05); A、B、C、F组子宫、肾上腺、胸腺重量较OVX组明显增加(P＜0.05).结论 雌激素类药物可增强去卵巢大鼠生殖内分泌免疫系统的功能.     

雌激素对去势雌鼠血清及膀胱组织e-NOS、AQPl含量的影晌

目的通过观察雌激素对去势雌鼠血清及膀胱e-NOS、AQPl含量的影响,进一步探讨雌激素替代治疗对绝经后尿道综合征的机制。方法成年健康SD雌性大鼠24只,随机分为空白组、对照组、尼尔雌醇组。摘除卵巢建立大鼠雌激素缺乏模型,灌胃给药4周后,用ELISA法测定血清及膀胱组织中e-NOS、AQP1的含量。结果尼尔雌醇组与对照组比较,血清e-NOS、AQPl含量显著增高（P〈0．05）．与空白组比较,差异无统计学意义（P〉0．05）。去势后膀胱e-NOS明显下降,补充雌激素后恢复正常水平,而AQPl去势前、后无显著改变,补充雌激素后亦无明显改变趋势。结论卵巢切除导致大鼠膀胱e-NOS发生下降,补充雌激素后恢复,而aQPZ无差异。e-NOS在绛．经后尿道综合征中起到直接作用．     

机械加载对大鼠薄型子宫内膜的修复作用

摘要：目的 探究脉冲式机械加载对薄型子宫内膜的疗效。方法 30只雌性SD大鼠随机分成假手术组（Sham 组）、薄型子宫内膜模型组（TE组）和机械加载治疗组（TE+L组），每组10只。在动情期采用95%乙醇宫腔注射法建 立薄型子宫内膜模型，Sham组宫腔注射生理盐水，TE+L组造模次日接受机械加载，加载力为5 N，频率为15 Hz，时间 为5 min/d，连续治疗15 d。HE染色观察子宫内膜组织形态变化，测量子宫内膜厚度、子宫内膜面积和腺体数目，免 疫组化染色法检测血管内皮生长因子（VEGF）和细胞增殖核抗原（Ki-67）的表达。结果 子宫组织学结果显示，TE 组子宫内膜厚度、子宫内膜面积和腺体数目较Sham组明显减少（P＜0.05），而TE+L组子宫内膜厚度、子宫内膜面积 和腺体数目较TE组明显增加（P＜0.05）。免疫组化染色结果显示，TE组子宫内膜中VEGF和Ki-67蛋白的阳性表达 率较Sham组显著降低（P＜0.05）。经过机械加载治疗后，TE+L组子宫内膜中VEGF和Ki-67蛋白的阳性表达率较TE 组显著升高（P＜0.05）。结论 机械加载能够有效修复大鼠薄型子宫内膜，该作用可能与机械加载促进子宫内膜的 细胞增殖和血管生成有关。     

内源性孤啡肽通过调节β1肾上腺素能受体对大鼠缺血性心律失常的影响

目的 探讨内源性孤啡肽（N/OFQ）对大鼠缺血性心律失常的影响以及心肌细胞β1肾上腺素能受体（β1-AR）在其中的作用。方法 采用结扎左冠状动脉前降支（冠脉）的方法制备大鼠急性心肌缺血模型。将60只大鼠按随机数字表法分为3组，即假手术组（Sham组）、冠脉结扎组（CAO组）和孤啡肽受体拮抗剂（UFP-101）预处理组（U+CAO组），每组20只。3组大鼠分别在冠脉结扎后15 min和1 h 2个时间点各处死10只大鼠。记录心电数据，采用Western blot法分别检测心肌细胞膜以及全细胞β1-AR的表达，RT-qPCR法检测β1-AR mRNA的表达。结果 与Sham组比较，CAO组出现缺血性心律失常，且主要集中在冠脉结扎后15 min内，UFP-101预处理显著降低心律失常发生。15 min 时：与 Sham 组比较，CAO 组全细胞 β1-AR、β1-AR mRNA 表达下调，而细胞膜 β1-AR 上调（均 P＜0.05），U+CAO组全细胞β1-AR蛋白及其mRNA表达无统计学意义（均P＞0.05），而细胞膜β1-AR下调（P＜0.05）；与CAO组比较，U+CAO组全细胞β1-AR蛋白及mRNA表达上调，而细胞膜β1-AR下调（P＜0.05）。1 h时：与Sham组比较，CAO组和U+CAO组全细胞β1-AR蛋白及mRNA表达上调，而细胞膜β1-AR下调（均P＜0.05）。结论 内源性N/OFQ可上调心肌细胞膜β1-AR参与大鼠缺血性心律失常过程。     

扶肾方对尿毒症腹膜透析大鼠腹膜超滤功能及VEGF-Notch信号通路的影响

目的　探讨扶肾方对尿毒症腹膜透析大鼠的腹膜超滤功能及腹膜组织Notch1、delta-样配体4（Dll4）、Notch胞内域（NICD）、Hes1、血管内皮生长因子（VEGF）及血管内皮生长因子受体-2（VEGFR-2）的影响。方法　采用随机数字表法将50只雄性SD大鼠分为正常组、模型组、扶肾方低剂量组（模型+扶肾方324 g/L灌胃）、扶肾方高剂量组（模型+扶肾方648 g/L灌胃）和塞来昔布组（模型+塞来昔布1.8 g/L灌胃）,每组10只。规律腹腔注射腹膜透析液4周,行腹膜平衡实验计算超滤量后处死大鼠,取腹膜组织,HE染色观察腹膜形态学变化,采用实时荧光定量PCR（qPCR）和蛋白印迹法检测Notch1、Dll4、NICD、Hes1、VEGF、VEGFR-2的mRNA和蛋白表达,蛋白印迹法检测p-VEGFR-2的蛋白水平。结果　模型组、扶肾方低剂量组、扶肾方高剂量组及塞来昔布组大鼠腹膜超滤量明显低于正常组,扶肾方高剂量组与塞来昔布组超滤量高于模型组和扶肾方低剂量组,塞来昔布组超滤量低于扶肾方高剂量组（P＜0.05）。腹膜HE染色显示,扶肾方低剂量组与高剂量组大鼠腹膜新生血管较模型组明显减少。与正常组比较,模型组大鼠腹膜组织Notch1、Dll4、NICD、Hes1 mRNA及蛋白表达均下调,VEGFR-2、VEGF mRNA及VEGFR-2、p-VEGFR-2、VEGF蛋白表达上调（P＜0.05）。与模型组比较,扶肾方低剂量组NICD、Hes1 mRNA及Notch1、Dll4、NICD、Hes1蛋白表达上调,VEGFR-2、VEGF mRNA及VEGFR-2、p-VEGFR-2、VEGF蛋白表达下调（P＜0.05）;扶肾方高剂量组Notch1、Dll4、NICD、Hes1 mRNA及Dll4、Hes1蛋白表达上调,VEGFR-2、VEGF mRNA及VEGFR-2、p-VEGFR-2、VEGF蛋白表达下调（P＜0.05）;塞来昔布组Notch1 mRNA及Notch1、Dll4蛋白表达上调,VEGFR-2、VEGF mRNA及p-VEGFR-2、VEGFR-2、VEGF蛋白表达下调（P＜0.05）。结论　扶肾方可改善腹膜超滤功能,该作用可能与上调腹膜组织Notch1、Dll4、NICD、Hes1 mRNA及蛋白表达,下调VEGFR-2、VEGF mRNA及VEGFR-2、p-VEGFR-2、VEGF蛋白表达有关。     

Effects of genistein on the mammary gland proliferation of adult ovariectomised Wistar rats

The effects of phytoestrogens on the female breast are discussed controversially. On the one hand, epidemiological and experimental data provide evidence that dietary phytoestrogens may prevent the development of breast cancer. On the other hand, in breast cancer cell lines and tumour models isoflavone phytoestrogens have been demonstrated to stimulate the growth of estrogen-dependent breast cancer cells. To further investigate the molecular effects of genistein (Gen) on the mammary gland, we treated non-tumour bearing, ovariectomised female Wistar rats with this phytoestrogen either subcutaneously (10 mg/kg body weight) or orally (100 and 200 mg/kg body weight) for 3 days. Estradiol (E(2), 0.004 mg/kg s. c.) and ethynylestradiol (EE, 0.1 mg/kg per os) served as reference compounds. In the breast tissue, mRNA and protein expression of the progesterone receptor (marker for estrogenicity) and PCNA (marker gene for proliferation) were examined by quantitative real-time PCR, Western blotting and immunohistochemistry; the uterotrophic response was assessed also. Treatment with Gen per os or s. c. results in a small but significant stimulation of the uterine wet weight. In the mammary gland, Gen stimulates the expression of progesterone receptor (PR) but, in contrast to E(2), the isoflavone does not stimulate the expression of PCNA. These findings resemble recent data demonstrating a differential ability of Gen to induce uterine gene expression and uterine proliferation. Our data indicate that in non-malignant breast tissue short-term administration of Gen, in contrast to more potent estrogens like E(2), does not induce proliferation. Chronic stimulation of proliferation is believed to be a key mechanism during the development of breast cancer. The limited ability of Gen to stimulate proliferation in this tissue could be an indication for a limited carcinogenic potency of Gen in the breast. In further investigations it is important to identify molecular differences between healthy and malignant breast tissue which may explain the different sensitivity towards Gen treatment.     

Hormonal activity of combinations of genistein, bisphenol A and 17β-estradiol in the female Wistar rat

Phytoestrogens have been described as weak estrogens,selective estrogen receptor mediators (SERMs) or to exhibit antiestrogenic properties. However, information about their activity in combination with xenoestrogens and 17β-estradiol in vivo, is limited. Therefore, the combinatory activity of the phytoestrogen genistein (Gen), the industrial chemical bisphenol A (BPA), and ethinylestradiol (EE) in ovariectomized Wistar rats was analyzed in this study. All compounds were administered orally on three consecutive days (EE at 30 μg, Gen at 100 mg and BPA at 200 mg per kg body weight per day). The pure antiestrogen fulvestrant (3 mg/kg) served as estrogen receptor (ER) antagonist control. Effects on uterine wet weight, height of the uterine epithelium, uterine clusterin (Clu) and complement C3 expression, and the height of the vaginal epithelium were examined. Treatment with Gen alone resulted in a moderate stimulation of uterine weight; in the vagina the height of the epithelium was strongly stimulated. BPA did not stimulate any of the above-mentioned parameters significantly. In combination with EE, Gen acted on most of the analyzed parameters in an additive manner, whereas BPA significantly antagonized the effects of EE on the uterine epithelium and uterine Clu expression. Given in combination with Gen, BPA was also able to antagonize the stimulatory effect of Gen on the uterine epithelium. In summary, our results demonstrate that Gen, in contrast to BPA, does not exhibit any antiestrogenic properties, even if given at high concentrations. The results of this study characterize BPA as a functional antiestrogen, very likely the result of a lack of ability to activate ER-mediated transactivation after binding to the receptor. This is not the case for Gen. Our results point to the involvement of complex molecular mechanisms in the action of Gen. These mechanisms, especially the role of ERβ have to be characterized in further investigations.     

Tamoxifen and estrogen attenuate enhanced vascular reactivity induced by estrogen deficiency in rat carotid arteries

Recent clinical trials showed that estrogen usage in postmenopausal women did not affect coronary heart disease incidence, in contrast to several laboratory studies showing that estrogen decreased vascular reactivity. We speculated that, in some arteries, estrogen deficiency enhances endothelial function to compensate for the increased vascular smooth muscle reactivity. In this study, we examined the role of endothelium-derived vasoactive factors and the influence of in vivo estrogen and/or tamoxifen treatment on vascular reactivity of estrogen-deficient rats. Common carotid arteries were isolated from sham-operated (control), ovariectomized (Ovx), estrogen- or tamoxifen-treated Ovx rats, and Ovx rats co-treated with estrogen and tamoxifen. U46619 or phenylephrine induced similar contractions in endothelium-intact rings from all groups. Interestingly, removal of endothelium unmasked enhanced contractions in Ovx rats, which was prevented by estrogen, tamoxifen, or estrogen+tamoxifen treatment. Contractions to high K(+) were higher in both endothelium-intact and endothelium-denuded arteries from Ovx rats. Estrogen or tamoxifen treatment normalized high K(+)-induced contraction. A gap junction blocker, 18alpha-glycyrrhetinic acid, revealed enhanced contractions to U46619 in the absence or presence of l-NNA. Western blotting showed enhanced expressions of gap junctional connexin 43 in Ovx group. This study suggests that ovariectomy increases functional expression of gap junction-mediated endothelium-derived hyperpolarizing factor. Also, vascular effects of ovariectomy can be reversed by estrogen, tamoxifen or estrogen+tamoxifen treatment, suggesting that tamoxifen confers estrogenic effects in the vascular system.     

Increased PKA activity and its influence on isoprenaline-stimulated L-type Ca2+ channels in the heart from ovariectomized rats

We previously showed that oestrogen confers cardioprotection by downregulating the cardiac beta1-adrenoceptor (beta1-AR). The present study examined the effect of oestrogen on the post beta1-AR signalling cascade, with particular emphasis on the activity of protein kinase A (PKA) and its influence on the L-type Ca2+ channel. Three groups of adult female Sprague-Dawley rats were used: sham-operated controls, bilaterally ovariectomized (Ovx) rats, and Ovx rats with oestrogen replacement (Ovx + E2), which restored the oestrogen concentration to normal. The electrically induced intracellular Ca2+ transient (E[Ca2+]i), 45Ca(2+)-uptake through cardiac L-type Ca2+ channels (Ca2+ channels), heart rate and force of contraction in response to beta-AR stimulation with 10 nM isoprenaline (Iso) in hearts from Ovx rats were significantly greater than those of control and Ovx + E2 rats. The basal and Iso-induced PKA activities were also higher in hearts from Ovx rats. KT5720, a selective PKA inhibitor, completely inhibited its potentiating effect on basal Ca2+ channel activity in the Ovx rat heart. On the other hand, expression of G proteins (G(alpha)s and G(alpha)i1-3)), basal and forskolin-stimulated cAMP accumulation, and responsiveness of PKA to cAMP, were not altered by Ovx. Interestingly, the PKA inhibitor at the same concentration significantly reduced the increases in PKA activity and Ca2+ channel activity upon beta-AR stimulation in all three groups of rats and the inhibitions were significantly greater in the Ovx rat than in the other two groups of rats. This study provides the first evidence that, in addition to downregulation of beta1-AR shown previously, suppression of PKA activity, which is partly responsible for the suppressed Ca2+ channel activity, also determines the E[Ca2+]i and cardiac contractility following beta-AR stimulation in the female rat.     

性激素对豚鼠心室乳头状肌动作电位和收缩的影响

AIM: To study the effects of sex hormones, estradiol (Est), progesterone (Pro) and testosterone (Tes) on the action potential (AP) and contraction of guinea pig papillary muscle. METHODS: Using conventional glass microelectrode and mechanical recording of myocardial contraction. RESULTS: Est slowed down the maximal rate of rise of phase 0 (Vmax) of AP at low concentration (1 mumol.L-1). At 10 mumol.L-1 and above, Est also prolonged AP duration (APD50 and APD90), effective refractory period (ERP) and decreased the maximal isometric tension (Pmax) and velocity of tension development (dT/dt) of contraction. Tes (100 mumol.L-1 - 1 mmol.L-1) prolonged APD90 and ERP with decreased Pmax and dT/dt. But Pro (1 mumol.L-1 - 1 mmol.L-1) had no effects on both AP and contraction. CONCLUSION: Est prolonged AP and depressed contraction of guinea pig papillary muscle.