大豆黄酮对大鼠乳腺发育作用的实验研究

本文研究了大豆黄酮对大鼠乳腺发育及其对垂体生长激素（ＧＨ）和催乳素（ＰＲＬ）分泌的影响，结果表明：１）胃饲或皮下注射大豆黄酮能显著提高去卵巢大鼠或正常处女大鼠乳腺重量和乳腺ＤＮＡ、ＲＮＡ含量；２）胃饲或皮下注射大豆黄酮能显著提高正常处女大鼠血清ＧＨ和ＰＲＬ含量，３）大豆黄酮能显著提高大鼠乳腺，垂体和下丘脑胞浆雌二醇受体的数目，并显著提高乳腺孕酮受体的数目，体外受体竞争结合试验结果表明：大豆黄酮与大     

大豆黄酮对母猪免疫功能和血清及初乳中GH、PRL、SS水平的影响

研究口服大豆黄酮对妊娠母猪及其仔猪的免疫功能和血清、初轧中生长激素（ＧＨ）、催乳素（ＰＲＬ）、生长抑素（ＳＳ）水平的影响，结果表明：１）大豆黄酮能明显提高母猪血清和初乳中特异性抗体（猪瘟抗体或溶血素）的水平，表明母猪整体和乳腺器官的体液免疫功能明显增强。２）通过对初乳的吸收，其新生仔猪血清中母源抗体水平明显高于对照组。３）母猪血清和初乳中ＧＨ、ＰＲＬ含量明显高于对照组，而血清ＳＳ含量显著低于对照组。本实验结果提示：垂体ＰＲＬ、ＧＨ和体内ＳＳ可能参与了大豆黄酮对猪免疫功能的调节过程。     

大豆黄酮的对母猪免疫功能和血清及初乳中GH,PRL,SS水平的影响

研究口服大豆黄酮对妊娠母猪及其仔猪的免疫功能和血清,初乳中生长激素、催乳素、生长抑素水平的影响,结果表明：１）大豆黄酮能明显提高母猪血清和初乳中特异性抗体的水平,表明母猪整体乳腺器官的体液免疫功能明显增强。２）通过对初乳的吸收,其新生仔猪血清中母源抗体水平明显对照组。３）母猪血清和初乳中ＧＨ、ＰＲＬ含量明显高于对照组,而血清ＳＳ含量显著低于对照组。本实验结果提示：垂体ＰＲＬ、ＧＨ和体内ＳＳ可能参与     

17－β－雌二醇诱发SD大鼠催乳素瘤形成过程中催乳素基因的表达

给ＳＤ大鼠皮下埋植内含１７－β－雌二醇硅橡胶管３０、６０、１２０天后，发现大鼠垂体重量随给药时间延长呈持续性增加；用放射免疫法测定血浆催乳素（ｐｒｏｌａｃｔｉｎ，ＰＲＬ）含量，亦明显依次升高；用Ｎｏｒｔｈｅｒｎ印迹杂交方法检测垂体细胞中ＰＲＬ基因，发现ＰＲＬｍＲＮＡ含量也依次有显著增加，但其增加却远低于血浆ＰＲＬ含量的增加，提示１７－β－雌二醇除了促进ＰＲＬ基因的转录外，还可能增加ＰＲＬｍＲＮＡ的翻译效率。     

大鼠中脑腹侧被盖区在睡眠－觉醒调节中的作用

本实验在３１只清醒自由行动的雄性ＳＤ大鼠进行。结果如下：（１）双侧中脑腹侧被盖区（ＶＴＡ）微量注射３．３ｎｍｏｌ溴隐亭后第２—３ｈ觉醒时间显著增加（Ｐ＜０．０１）;６．６ｎｍｏｌ溴隐亭有类似效果;０．６６和１．３３ｎｍｏｌ溴隐亭无明显作用。（２）同样方法ＶＴＡ微量注射２ｎｍｏｌ和４ｎｍｏｌＳＣＨ２３３９０后第２—３ｈ觉醒时间明显减少（分别为Ｐ＜０．０１和Ｐ＜０．０５）,但注射３．４ｎｍｏｌ舒必利则无效。（３）红藻氨酸（０．３μｇ）双侧ＶＴＡ注后一周,大鼠白天觉醒减少,夜间无明显变化。以上结果表明溴隐亭微量注射到ＶＴＡ可能通过Ｄ１受体使多巴胺神经元活动增加而产生致觉醒作用;另外ＶＴＡ中ＤＡ神经元对于维持日间的觉醒可能有紧张性作用。     

大鼠实验性脾虚证胰腺组织化学研究

用成年雄性Ｗｉｓｔａｒ大鼠３０只,分为（１）正常对照组,喂饲自来水。（２）脾虚组,用苦降破气中药和饮食失节法致成脾虚模型。（３）自然恢复组,动物致虚后,喂饲自来水。（４）中药治疗组。取四组动物胰腺进行ＲＮＡ,琥珀酸脱氢酶（ＳＤＨ）,乳酸脱氢酶（ＬＤＨ）,三磷酸腺苷酶（ＡＴＰａｓｅ）,葡萄糖－６－磷酸酶（Ｇ－６－Ｐａｓｅ）和硫胺素焦磷酸酶（ＴＰＰａｓｅ）组织化学反应和观察,并对ＳＤＨ,ＬＤＨ,ＲＮＡ进行了显微分光光度计定量测定。本研究结果表明,脾虚组胰腺泡细胞的ＲＮＡ,ＳＤＨ,ＡＴＰａｓｅ,Ｇ－６－Ｐａｓｅ,ＴＰＰａｓｅ含量和活性都低于对照组,而ＬＤＨ活性高于对照组。治疗组与自然恢复组相比,治疗组胰腺泡细胞以上指标接近对照组。定量测定与定性的结果一致。本研究表明,脾虚证时胰腺泡细胞上述几种酶活性和ＲＮＡ明显下降,可能在脾虚证发病中起主要作用,中药治疗有显著改善     

大豆黄酮对大鼠肌肉生长和几种内源激素水平的影响

给雄性、雌性和雄性去势大鼠皮下注射大豆黄酮［３ｍｇ／（１００ｇ体重·天）］１６天。结果：雄性大鼠日增重提高１４．７％（Ｐ＜０．０５）,耗料与增重比降低１２．０％,后腿肌重和后腿肌总ＲＮＡ含量显著增加,而总ＤＮＡ含量无显著变化;血清脲氮水平显著下降,血清睾酮、雌二醇、生长激素和β－内啡肽含量显著提高。雄性去势大鼠日增重、后腿肌重无显著变化,血清睾酮、生长激素和β－内啡肽水平虽显著高于对照组,但睾酮水平仅为同等条件下完整大鼠的８％左右。雌性大鼠日增重降低１９．０％（Ｐ＜０．０１）,耗料与增重比提高１７．８％,血清睾酮、雌二醇和生长激素水平显著降低。试验结果表明：大豆黄酮对大鼠肌肉生长和几种内源激素水平的影响呈现性别差异,对雄性大鼠肌肉生长的促进作用依赖于睾丸的内分泌机能。     

日粮添加塞曼特罗（CIM）对大鼠生长胴体组成及GH水平的影响

选用２４只２月龄ＳＤ处女鼠配对分组,实验组日粮添加１０μｇ／ｇ塞曼特罗（ＣＩＭ）,试验期３０天。与对照组比较,ＣＩＭ显著提高大鼠生长速度（２７．３０％,Ｐ＜０．０１）和胴体比率,降低腰胁部脂肪重,提高腓肠肌、比目鱼肌和趾浅屈肌的鲜重和ＲＮＡ合量及ＰＮＡ／ＤＮＡ值,同时提高大鼠垂体和血清ＧＨ水平分别达３６．７０％（Ｐ＜０．０１）和２３．７７％（Ｐ＜０．０５）,降低血清脲氮含量。表明ＣＩＭ可显著促进大鼠生长,降低体脂含量,促进肌肉肥大,促进蛋白沉积。其作用机理可能还与其促进ＧＨ的合成和分泌有关。     

半胱胺对大鼠泌乳量及血液,组织几种激素含量的影响

选用４０只Ｗｉｓｔａｒ泌乳大鼠进行配对实验。哺乳期第８天起,实验母鼠灌服半胱胺（ｃｙｓｔｅａｍｉｎｅ,ＣＳ）８０ｍｇ／ｋｇＢ．Ｗ,每隔５天一次,直至哺乳第３０天。实验中记录泌乳量、仔鼠体重及采食量,并用放免法测定血液及组织生长抑素（ＳＳ）、生长激素（ＧＨ）、催乳素（ＰＲＬ）的含量。结果表明,ＣＳ使母鼠哺乳期第１０、１５、２０天的泌乳量明显提高（Ｐ＜０．０５）,第２５天泌乳量有所增加（Ｐ＞０．０５）,第３０天差异不明显;母鼠哺乳期采食量略有增加（Ｐ＞０．０５）,料／奶比明显下降（Ｐ＜０．０５）;哺乳期第１５天的血液、下丘脑和大脑皮层ＳＳ含量明显下降,血液ＧＨ含量显著升高（Ｐ＜０．０５）,但第２５天无明显变化;母鼠哺乳期血液ＰＲＬ含量明显下降（Ｐ＜０．０５）。提示,ＣＳ能促进大鼠泌乳,而抑制体内ＳＳ,提高内源性ＧＨ水平,可能为ＣＳ的主要作用机制。     

胎脑黑质脑内移植矫正PD鼠纹状体内脑啡肽mRNA过度表达

用６－ＯＨＤＡ损毁大鼠一侧黑质—纹状体通路可引起ＰＤ模型鼠脑纹状体内多巴胺匿乏．同时,亦可导致脑啡肽ｍＲＮＡ过度表达。我们用地高辛标记的ｃＲＮＡ探针对纹状体内脑啡肽ｍＲＮＡ含量进行了斑点杂交定量研究,发现损伤侧脑啡肽ｍＲＮＡ含量较健侧增高８０％,胎中脑移植到失神经支配的纹状体内,脑啡肽ｍＲＮＡ过度表达得以矫正至正常水平,说明胎多巴胺能神经元脑内移植能够调节脑啡肽基因表达,提供了移植物能与宿主发生神经整合、建立突触联系的间接证据。     

Effect of chronic suppression of growth hormone secretion, by SMS 201-995 on lactation in mice

The effect of chronic suppression of growth hormone (GH) secretion by SMS 201-995 on lactation was studied in primiparous C3H/He mice. Mammary gland DNA content on day 12 of lactation was significantly lower in SMS 201-995 treated mice than in the control. There were little differences between groups in mammary gland RNA content and litter growth on day 12 of lactation. That was associated with a slightly higher RNA/DNA ratio and a significant increase in food intake during lactation. These results indicate that inhibited mammary gland growth by GH suppression has little effect on lactation. The smaller mammary gland can compensate by increasing its secretory activity.     

Alkaline ribonuclease and ribonuclease inhibitor in mammary gland during the lactation cycle and in the R3230AC mammary tumour.

Alkaline RNAase (ribonuclease) and RNAase inhibitor were assayed to determine the potential role of the degradative process in regulating the amount of RNA in the mammary gland and mammary tumour. Very little free alkaline RNAase activity was found in the cytosol fraction of the mammary gland of virgin, pregnant, lactating or involuting Fischer rats. However, addition of p-chloromercuribenzoate to the assay medium revealed latent RNAase which, when expressed on a DNA basis, decreased during pregnancy and lactation. The cytosol latent RNAase is stable in 0.125 M-H2SO4. The non-cytosol RNAase activity also decreased during pregnancy and lactation. Addition of Triton X-100 produced slightly higher activity at all stages tested. The inhibitor activity in rat mammary gland was very low before pregnancy, increased gradually during pregnancy and more dramatically at parturition, continued to increase throughout lactation and returned to resting-gland values by the sixth day of involution. The increase during pregnancy may be due to the increased cellularity of the gland, whereas the gain during lactation was more than could be accounted for by increases in cell number. The R3230AC transplantable mammary tumour resembles the normal gland in early lactation with respect to both its cytosol and non-cytosol alkaline RNAase activities and its moderately high content of RNAase inhibitor. The relatively high inhibitor and low RNAase activities in both the gland of the lactating rat and in the tumour are of potential significance in maintaining high amounts of RNA and increased rates of protein synthesis in these tissues.     

Dynamic state of site-specific DNA methylation concurrent to altered prolactin and growth hormone gene expression in the pituitary gland of pregnant and lactating rats

The regulatory mechanism for the hormonal control of prolactin (PRL) and growth hormone (GH) gene expression in rat pituitary gland during gestation and lactation is verified in this study. The level of PRL-specific mRNA (mRNAPRL) sequences in the pituitary gland is elevated in the later part of gestation and more prominently so in lactation. In contrast the expression of GH gene is inhibited in the same tissue during gestation and lactation resulting in the dramatic decrease in the level of GH-specific mRNA (mRNAGH) sequences. We now demonstrate the influence of a tissue-specific altered DNA methylation pattern on the temporal modulation of expression of PRL and GH genes in the pituitary gland during alternate physiological states. An altered methylation pattern of specific "-C-" residues only in the coding region of PRL and GH gene can be detected concurrently with the altered level of expression of these genes in the pituitary gland during gestation and lactation. These results also demonstrate the dynamic state of methylation of specific -C- residues during the transition of these two genes from one state of expression to another in the same tissue. A correlation between site-specific DNA methylation and tissue-specific expression of PRL and GH gene in pituitary gland is reported. Thus a role of DNA methylation in the hormonal control of PRL and GH gene expression in physiological states such as pregnancy and lactation is proposed.     

Induction of glutathione S-transferases A, B and C in rat liver cytosol by trans-stilbene oxide

RNAase H, which catalyzes the hydrolysis of the RNA moiety of an RNA-DNA hybrid, was measured in the mammary gland of virgin, pregnant, lactating, and weaning Fischer rats and in the R3230AC mammary tumor grown in the same animals. In the normal mammary gland when DNA levels were low, as in the virgin state or during involution, RNAase H activity was also low. During pregnancy and lactogenesis when DNA levels increased, RNAase H activity, either on the basis of mammary gland weight or DNA content, also increased. During lactation when cellular proliferation ceases but rates of RNA and protein synthesis continue to reach peak values, RNAase H activity decreased. Compared to the corresponding enzyme from host glands, RNAase H from the R3230AC mammary tumor grown in pregnant and lactating hosts changes similarly, but to a lesser extent. The RNAase H activity which, ona tissue weight basis, was higher than in normal tissue also increased during pregnancy and directly after parturition, but decreased during lactation. During pregnancy these changes were accompanied by an increase in tumor DNA values. During lactation the tumor DNA values returned to the level seen in virgin hosts. These results are consistent with a role for RNAase H in DNA replication in rat mammary gland and in R3230Ac mammary tumor.     

Prolactin and growth hormone stimulation of lactation in mice requires thyroid hormones.

This experiment tested the hypothesis that thyroid hormones are essential for a milk production response to growth hormone (GH) and prolactin (PRL). Prior to breeding, female transgenic mice expressing the herpes simplex type-I thymidine kinase in the thyroid were treated with ganciclovir to ablate thyroid follicular cells. To provide for normal gestation, thyrocyte-ablated mice were supplied thyroxine (T4) in drinking water (0.2 microgram/ml) until 7 days before parturition. Litter size was adjusted to 9 pups, hormone administration began on Day 2 of lactation, and mice were sacrificed on Day 12. There were 5-6 mice in each of 7 treatments that included nonablated controls, thyrocyte-ablated controls, and thyrocyte-ablated mice treated with T4, GH, PRL, GH + T4, and PRL + T4. Thyroxine was administered in drinking water, and GH and PRL (20 microgram/d) were administered by subcutaneous injection. Compared with thyrocyte-ablated controls, litter weight gain was unaffected when dams were treated with GH, PRL, or T4 alone. However, when dams were treated with GH or PRL in combination with T4, litter weight gain increased 13% compared with thyrocyte-ablated controls and 18% compared with GH or PRL-treated mice. Concentration of T4 in serum of pups averaged 62 ng/ml and did not differ among treatments. Concentration of T4 in serum of dams averaged 76 ng/ml when T4-treated. Thyroxine 5'-deiodinase (5'D), the enzyme that converts T4 to triiodothyronine, was quantitated in liver, kidney, and mammary gland. Quantity of 5'D was lower in liver and kidney of thyrocyte-ablated dams without T4 than in respective tissues of mice treated with T4, and there was no effect of GH or PRL. However, in mammary gland, 5'D was increased by treatment with GH, PRL, or T4. Data show that thyroid hormones are necessary for a galactopoietic response to GH and PRL and demonstrate a unique organ-specific regulation of 5'D by galactopoietic hormones.     

Effects of serum on mammary epithelial proliferation in vitro during mammary gland development

The proliferative response of mammary gland epithelium from nonpregnant, pregnant, and lactating mice to mammary serum factor and insulin was studied in vitro. Mammary gland epiithelium from nonpregnant and lactating animals has a delayed proliferative response to mammary serum factor and insulin when compared to the response of epithelium from pregnant animals. The results show that as the animals go through pregnancy into lactation the mammary gland epithelium becomes less responsive to mammary serum factor while it retains its responsiveness to insulin. The concentration of mammary serum factor in sera from animals at various physiological stages is constant. Sera from hypophysectomized rats, on the other hand, show a 50% drop in mammary serum factor activity. This loss of activity cannot be reversed by injecting prolactin, 17-beta-estradiol, or growth hormone into the hypophysectomized animals. A hypothesis that the mammary gland is composed of two proliferative epithelial populations is developed, and the possible role of prolactin in stimulating DNA synthesis is discussed.     

The mRNA encoding a parathyroid hormone-like peptide is produced in mammary tissue in response to elevations in serum prolactin

During lactation, a dramatic rise in serum PRL stimulates milk production, resulting in a substantial rise in calcium mobilization from gut and bone. We found that the production of a newly characterized calcium-mobilizing PTH-like peptide (PTH-LP) by mammary tissue was tightly linked to lactation, suggesting a possible role for PRL in the expression of PTH-LP. Here it is shown that suckling results in both an elevation in serum PRL and the appearance of PTH-LP mRNA in mammary tissue. Bromocriptine, a potent inhibitor of PRL secretion, blocked the suckling-associated rise in serum PRL and the subsequent induction of PTH-LP mRNA in mammary gland. Furthermore, injection of PRL dramatically induced PTH-LP mRNA in unsuckled puerperal glands, but not in glands on day 21 of pregnancy. Thus, the correlation between serum levels of PRL and the expression of PTH-LP mRNA in mammary tissue extends the role of PRL in milk production and suggests a possible mechanism for the PRL effects on calcium metabolism.