多胺的生殖生物学作用及其研究进展

多胺是一类聚阳离子化合物,包括精胺、亚精胺和腐胺等。哺乳动物体内多胺来源于氨基酸合成或从饮食中摄取,多胺能够清除细胞内过多的活性氧簇(ROS),调节其氧化应激水平。多胺在雄性和雌性的生殖过程和胚胎/胎儿发育中起重要作用。研究发现,多胺参与调节细胞生长和基因表达,且与有丝分裂、减数分裂有关。在雄性,多胺与精子生成相关,并调节精子活性;在雌性,多胺与卵泡发育及排卵有关,且参与调节类固醇激素生成。在体外成熟(IVM)中外源性添加多胺,可有效地减少卵母细胞非整倍体率并且改善其胚胎发育。此外,多胺缺乏会导致胚胎发育停滞。多胺参与胎盘发育以及在胎儿发育过程中母婴的物质交换。综述多胺生物学功能及其对配子发生及胎盘发育的作用。     

哺乳动物体内γ-谷胺酰转肽酶活性的研究进展

γ-谷胺酰转肽酶(gamma-glutamyltranspeptide,γ-GT,[EC 2.3 2.2])催化γ-谷胺酰基团的转移,在哺乳动物体内其主要功能是参与"γ-谷胺酰循环",与氨基酸的跨细胞膜转运及谷胱甘肽(glutathione,GSH)水平的调节有关.在体内γ-谷胺酰基的供体是GSH,而受体一般为L-氨基酸.本文对近年来国外文献报道的哺乳动物体内γ-GT活性影响的因素、γ-GT对机体代谢的作用及相关性疾病等研究进展,作一综述.     

雄性生殖中热休克蛋白作用的研究进展

热休克蛋白(heat shock protein,HSP)是指所有生物细胞在应激原刺激后,发生热休克反应时产生的一类细胞伴侣蛋白的总称。该类蛋白在细胞生命过程中可参与蛋白的折叠、装配及运输等活动,对调控细胞的生长、存活及分化起着重要作用。在哺乳动物的雄性生殖领域,HSP家族参与精子发生、精卵结合、精子获能及受精等一系列活动,与雄性生殖过程密切相关。因此,研究HSP家族在雄性生殖中的生物学作用对进一步阐明男性不育的发病机制及后续男性生殖调节的研究都具有十分重要的意义。     

雄性生殖中热休克蛋白作用的研究进展

热休克蛋白(heat shock protein,HSP)是指所有生物细胞在应激原刺激后,发生热休克反应时产生的一类细胞伴侣蛋白的总称。该类蛋白在细胞生命过程中可参与蛋白的折叠、装配及运输等活动,对调控细胞的生长、存活及分化起着重要作用。在哺乳动物的雄性生殖领域,HSP家族参与精子发生、精卵结合、精子获能及受精等一系列活动,与雄性生殖过程密切相关。因此,研究HSP家族在雄性生殖中的生物学作用对进一步阐明男性不育的发病机制及后续男性生殖调节的研究都具有十分重要的意义。     

褪黑素与健康关系的研究进展

褪黑素(Melatonin MT)是哺乳动物和人类松果腺主要在夜间分泌的一种吲哚胺类激素，它的分子式为C13N2H16O2，分子量为232．27，熔点为116℃～118℃，化学名称为N-乙酰基-5-甲氧基色胺。它每日所分泌的量极其微小，但它的作用却极其强大，具有广泛的生理和药理作用，对生物的昼夜节律，性成熟及生殖、免疫反应、肿瘤、衰老等均具有作用。     

RF酰胺相关肽3调节雌性哺乳动物生殖活动的研究进展

雌性哺乳动物的生殖受下丘脑-垂体-卵巢(hypothalamus-pituitary-ovary,HPO)轴调控,外周和中枢的诸多刺激因子参与其中并组成复杂的调节网络.哺乳动物下丘脑神经肽RF酰胺相关肽3(RFamide-related peptide 3,RFRP-3)是下丘脑中的HPO轴抑制因子,通过G蛋白耦联受体...     

瘦素对女性生殖内分泌影响的研究进展

瘦素(leptin)是肥胖基因(ob基因)编码的产物,由白色脂肪组织分泌入血。leptin与leptin受体结合,通过JAK-STAT途径发挥生理作用,不仅能调节食欲、控制饮食、抑制脂肪合成、促进脂肪分解、调控能量代谢,还可影响女性生殖内分泌系统,调节下丘脑-垂体-卵巢轴,影响生殖功能及女性排卵,参与青春期的启动,是连接营养与生殖的代谢信号。就leptin对女性生殖内分泌的影响的研究进展作一综述。     

瘦素对女性生殖内分泌影响的研究进展

瘦素(leptin)是肥胖基因(ob基因)编码的产物,由白色脂肪组织分泌入血.leptin与leptin受体结合,通过JAK-STAT途径发挥生理作用,不仅能调节食欲、控制饮食、抑制脂肪合成、促进脂肪分解、调控能量代谢,还可影响女性生殖内分泌系统,调节下丘脑-垂体-卵巢轴,影响生殖功能及女性排卵,参与青春期的启动,是连接营养与生殖的代谢信号.就leptin对女性生殖内分泌的影响的研究进展作一综述.     

孕期接触职业性噪声的病例对照研究

根据文献报道,噪声似乎会对生殖产生有害影响,尤其是对较小的哺乳动物。噪声接触研究已显示出啮齿动物出生率下降及胚胎重吸收减少和生长迟缓。在较大的哺乳动物(牛、马、猪)中,目前尚无噪声对其妊娠影响的令人信服的证据。噪声对人妊娠影响的流行病学目前研究尚不多。已有资料提示噪声会导致居住在飞机场附近的孕妇分娩低体重新生儿。     

转化生长因子β与生殖功能调节研究进展

转化生长因子β是一类具有多种生物学作用、多细胞来源的细胞因子.越来越多的证据表明,转化生长因子β与生殖各方面存在密切关系,影响生殖活动各个环节,包括下丘脑-垂体-卵巢轴的调控、子宫内膜周期性变化、胚胎着床和发育以及局部免疫调节等.对其深入研究将有助于进一步了解人类生殖调节.     

Polyamines in human and animal milk

Polyamines are highly regulated polycations which are essentially involved in cell growth and differentiation. Polyamines in food significantly contribute to the polyamine body pool. Dietary polyamines exert various direct and indirect trophic effects on the rat's immature intestine and play an important role during intestinal maturation. Human milk and that of other mammalians contain relatively high levels of polyamines which are essential luminal growth and maturation factors. The polyamines spermidine and spermine as well as their diamine precursor putrescine are ubiquitous normal constituents of all prokaryotic and eukaryotic cells and are essentially involved in various processes of cell growth and differentiation (Pegg & McCann, 1982; Tabor & Tabor, 1984; Seiler, 1990).     

Polyamines: metabolism and implications in human diseases

Classically, polyamines is a family of molecules (i.e. putrescine, spermine, spermidine) derived from ornithine according to a decarboxylation/condensative process. More recently, it has been demonstrated that arginine can be metabolised according to the same pathway leading to agmatine formation. Polyamines are essential for the growth, the maintenance and the function of normal cells. The complexity of their metabolism and the fact that polyamines homeostasis is tightly regulated support the idea that polyamines are essential to cell survival. Multiple abnormalities in the control of polyamines metabolism might be implicated in several pathological processes. This paper summarises the knowledge about polyamines metabolism and point out the importance of these molecules as a target for the development of therapeutic tools and nutritional strategy.     

Critical windows of exposure for children's health: the reproductive system in animals and humans

Drugs and environmental chemicals can adversely affect the reproductive system. Currently, available data indicate that the consequences of exposure depend on the nature of the chemical, its target, and the timing of exposure relative to critical windows in development of the reproductive system. The reproductive system is designed to produce gametes in far greater excess than would seem to be necessary for the survival of species. Ten to hundreds of millions of spermatozoa are generated daily by most adult male mammals, yet very few of these germ cells succeed in transmitting their genetic material to the next generation. Although the number of oocytes produced in mammalian females is more limited, and their production occurs only during fetal life, most ovaries contain several orders of magnitude more oocytes than ever will be fertilized. Toxicant exposures may affect critical events in the development of the reproductive system, ranging from early primordial germ cell determination to gonadal differentiation, gametogenesis, external genitalia, or signaling events regulating sexual behavior. Although there are differences between the human reproductive system and that of the usual animal models, such models have been extremely useful in assessing risks for key human reproductive and developmental processes. The objectives for future studies should include the elucidation of the specific cellular and molecular targets of known toxicants; the design of a systematic approach to the identification of reproductive toxicants; and the development of sensitive, specific, and predictive animal models, minimally invasive surrogate markers, or in vitro tests to assess reproductive system function during embryonic, postnatal, and adult life.     

Polyamine excretion in depleted patients with gastrointestinal malignancy: effect of perioperative nutrition and tumor removal.

Polyamines, synthesized by all mammalian cells, are involved in protein and energy metabolism. We measured urinary excretion of polyamines, putrescine, spermidine, spermine, and their metabolites N1-acetylspermidine and N8-acetylspermidine, resting energy expenditure, and nitrogen excretion in 12 depleted patients with gastrointestinal malignancy during preoperative and postoperative parenteral nutrition and in 7 patients with multiple trauma receiving similar parenteral nutrition. During preoperative nutrition support, the excretion of putrescine (p less than .05) and total polyamines (p less than .01) increased by 420% and 60%, respectively. Increases in energy balance and resting energy expenditure during nutrition could entirely explain the observed changes in polyamine excretion. Preoperatively, the excretion of N1-acetylspermidine (p less than .05), N8-acetylspermidine (p less than .001) and total polyamines (p less than .05) was higher in patients with a surgically noncurable tumor than in those with a surgically curable tumor. The energy balance and resting energy expenditure could also explain the differences in polyamine excretion between patients with surgically curable and noncurable disease, excluding the increased N8-acetylspermidine. Postoperatively, the excretion of N8-acetylspermidine in patients with multiple trauma without malignancy and in patients with palliative operation was similar, and was higher than in patients with a totally resected malignancy (p less than .01). Our results suggest that the excretion of polyamines reflects the activity of energy metabolism in general and that polyamine excretion is not specific for any particular disease.     

Dietary Polyamine Intake and Polyamines Measured in Urine

Dietary polyamines have recently been associated with increased risk of pre-malignant colorectal lesions. Because polyamines are synthesized in cells and taken up from dietary sources, development of a biomarker of exposure is challenging. Excess polyamines are primarily excreted in the urine. This pilot study seeks to identify dietary correlates of excreted urinary polyamines as putative biomarkers of exposure. Dietary polyamines/other nutrients were estimated from a food frequency questionnaire (FFQ) and correlated with urinary levels of acetylated polyamines in 36 men using 24-h urine samples. Polyamines, abundant in cheese and citrus, were highly positively correlated with urinary N⁸-acetylspermidine (correlation coefficient; r = 0.37, P = 0.03), but this correlation was attenuated after adjustment for total energy intake (r = 0.07, P = 0.68). Dietary energy intake itself was positively correlated with urinary total acetylated polyamine output (r = .40, P = 0.02). In energy-adjusted analyses, folic acid and folate from food were associated with urinary N¹,N¹²-diacetylspermine (r = 0.34, P = 0.05 and r = ?0.39, P = 0.02, respectively). Red meat negatively correlated with total urinary acetylated polyamines (r = ?0.42, P = 0.01). Our findings suggest that energy, folate, folic acid, saturated fat, and red meat intake, as opposed to FFQ-estimated dietary polyamines, are correlated with urinary polyamines.     

Effect of spermine on membranolytic effect of vitamin A in rats

The effect of spermine on membranolytic effect of vitamin A has been studied on mitochondrial membrane integrity by examining phospholipase A2 activity and membrane phospholipids. Spermine arrest the vitamin A induced activity of mitochondrial phospholipase A2. The function of vitamin A in vision is fairly well understood. Though the part that vitamin A plays in vision is of high significance; vitamin A deficient animal not only become blind but eventually die. This indicates that vitamin A plays an indispensable role in general metabolism. The mechanism of absorption, transport and storage of vitamin A have been intensively studied [1, 8, 9]. Administration of vitamin A in large doses for prolonged periods is found to be toxic. This toxicity is termed as hypervitaminosis A. Excess of vitamin A to animals have been found to cause membrane labilization of various cellular organelles, e.g. mitochondria, lysosomes and release their contents. Alternations in membrane functions of liver mitochondria have also been observed in rats given excess of vitamin A. Polyamines have been shown to stabilize membrane structure against lysis or swelling for several microorganism and mammalian subcellular fractions [2, 4, 5, 7]. The stability of mitochondrial and lysosomal membranes are in reciprocal relationship with the activity of endogenous phospholipases bound to these membranes [4, 11]. Polyamines were shown to inhibit phospholipase A2 activity of heart mitochondria [12]. Phospholipase A2 detaches the fatty acid from the position of phosphatidyl choline, and the lysolecithin formed has a detergent effect that can produce membrane destabilization. The mechanism of inhibition by polyamines appears to be related to the effect of basic proteins as phospholipase digestion.(ABSTRACT TRUNCATED AT 250 WORDS)     

Activity of peroxisomal enzymes,and levels of polyamines in LPA-transgenic mice on two different diets

Background  

In man, elevated levels of plasma lipoprotein (a)(Lp(a)) is a cardiovascular risk factor, and oxidized phospholipids are believed to play a role as modulators of inflammatory processes such as atherosclerosis. Polyamines are potent antioxidants and anti-inflammatory agents. It was therefore of interest to examine polyamines and their metabolism in LPA transgenic mice.     

Clinical role of polyamine analysis: problem and promise

Polyamines are ubiquitous cell components for growth. They play an important role in cell proliferation, cell growth and synthesis of protein and nucleic acids. Cells that are stimulated to reproduce demonstrated early increases in biosynthetic enzymes involved in polyamine synthesis and subsequent elevations in polyamine levels. Extracellular fluid polyamine concentrations that reflect the intracellular events may be useful as rapid indicators of therapy in disorders which involve altered cell growth. More complex analytical approaches are required to isolate, identify and quantitate these polyamines. Most of the methods require an extraction procedure to remove interfering amino acid derivatives. Daily monitoring of plasma and urine polyamine levels in many pathological states may provide a non-invasive biochemical marker of the existing disease activity or response to therapy or to screen for drug efficacy. Automated high-performance liquid chromatography, with post or pre-column derivatization and fluorescence or electrochemical detection is frequently used for the simultaneous quantitation of picomolar quantities of polyamines. Recently, a new immuno-cytochemical model system incorporating an enzyme-linked immunosorbent assay for specific polyamines has been developed. The increasing momentum of basic science information in the polyamine discipline may lead clinicians to regard polyamines, their metabolites and antimetabolites as sources of effective treatment.     

Effects of radiofrequency electromagnetic fields on mammalian spermatogenesis

This article reviews studies about the effects of radiofrequency electromagnetic (RF EM) fields on male reproductive system and reproductive health in mammals. According to current data, there are almost 4 million active mobile phone lines in Croatia while this number has risen to 2 billion in the world. Increased use of mobile technology raises scientific and public concern about possible hazardous effects of RF fields on human health. The effects of radiofrequencies on reproductive health and consequences for the offspring are still mainly unknown. A number of in vivo and in vitro studies indicated that RF fields could interact with charged intracellular macromolecular structures. Results of several laboratory studies on animal models showed how the RF fields could affect the mammalian reproductive system and sperm cells. Inasmuch as, in normal physiological conditions spermatogenesis is a balanced process of division, maturation and storage of cells, it is particularly vulnerable to the chemical and physical environmental stimuli. Especially sensitive could be the cytoskeleton, composed of charged proteins; actin, intermedial filaments and microtubules. Cytoskeleton is a functional and structural part of the cell that has important role in the sperm motility, and is actively involved in the morphologic changes that occur during mammalian spermiogenesis.