Soil reproduction in steppe ecosystems of different ages

Features of the development of steppe chernozems were established based on the study of soils of different age groups at archaeological sites. Differences in the formation of phytomass and morphological maturity of the soil profile in the recovery of different age successions were shown. A regional model of the humus horizon steppe soil over time allowed us to estimate the time interval at which the processes of humus accumulation and morphological maturity of the soil profile are relatively at equilibrium, viz., 1700–1900 years.     

Toxic effects of cadmium on GABA and taurine content in different brain areas of adult male rats

This work assesses the possible changes in gamma amino butyric acid (GABA) and taurine content in the hypothalamus, the median eminence and striatum after the exposure to various doses of cadmium. Cadmium chloride (CdCl2) was administered in the drinking water at the doses of 5, 10, 25, 50 or 100 ppm to adult male rats for 1 month. In the anterior hypothalamus, taurine and GABA content decreased with the dose of 10 ppm of CdCl2 only. Cadmium exposure decreased both GABA and taurine content in mediobasal hypothalamus except for the 50 ppm dose. In posterior hypothalamus GABA and taurine content was not affected by cadmium treatment. As far as the median eminence, 5 or 10 ppm of CdCl2 increased taurine concentration, and at a dose of 5 ppm enhanced GABA content. A significant decrease of GABA and taurine concentration was seen in the striatum at any dose of cadmium used. The concentration of cadmium increased in the hypothalamus and in the striatum in animals receiving CdCl2 in the drinking water at doses of 25, 50 or 100 ppm. The results indicate that cadmium globally decreased GABA and taurine content in the brain areas studied through effects that were not dose dependent.     

慢性镉负荷雄性大鼠的睾丸及生殖内分泌功能活动

选择健康SD雄性成年大鼠60只,随机分成对照组（C组）、镉负荷中剂量组（M组）和镉负荷高剂量组（H组）,每天分别饲喂含镉0,5,10mg/kg的大鼠全价饲料,连续6周,研究了镉负荷对大鼠睾丸及生殖内分泌功能活动的影响。结果显示：在整个实验期内,M和H组大鼠睾丸组织中的镉含量极明显上升,锌含量销有下降,与对照组差异不显著;血浆镉、锌含量虽分别表现稍有升高和下降,但与对照组比较无明显差异;H组睾丸精子头计数和每日精子生成量在镉负荷第3周极显著下降,第6周时,M和H组均极明显低于对照组;在整个实验期内,H组大鼠ALP活明显低于C组;LDH－X活性在M和H组大鼠均极明显低于C组;M和H组血浆T水平下降,均低于或显著低于C组;3组间的FSH和LH水平无明显差异。结果提示：慢性镉负荷在睾丸组织中逐步蓄积可引起睾丸一些酶活性改变、精子生成减少及内分泌功能活动低下。     

Mitotic activity of prolactin cells in the pituitary glands of male and female rats of different ages

Summary The ultrastructural localization of the glycoprotein D2 in rat adrenal gland was investigated using immunohistochemical methods, and D2 localization in cultures of adult bovine chromaffin cells was studied by immunofluorescence. D2 was found to be situated on nerve fibers passing through the adrenal cortex and in the medulla zone, and also on the surface of all chromaffin cells. In addition, it was strongly expressed on the surface of glial (Schwann) cells. Cortical cells were unreactive to the antiserum. In cultures, all adrenalin and noradrenalin [dopamine--hydroxylase (DBH)-positive] cells were surface labelled for D2. A less frequent second cell type was recognized in vitro which was DBH negative but D2 positive. Such cells were presumed to be Schwann cells. These data are discussed in terms of the developmental origin of the cells and with regard to the putative functional rôle of D2 in cell adhesion phenomena.     

Chronic fenfluramine treatment of rats with different ages: Effects on brain oxidative stress-related parameters

Fenfluramine is an anorectic drug widely used for the regulation of food intake that presents some adverse effects at the central and peripheral levels. d-Fenfluramine, an isomer of dl-fenfluramine, is postulated to be more effective and to induce less side effects than the racemic compound. These drugs act preferentially on the serotonergic system. Some authors have suggested that fenfluramine causes a degeneration of serotonergic neurons. Alterations of the serotonergic system are also observed during the aging process, and in this case, a relationship with reactive oxygen species has been already established. In view of these data, the present study was conducted to investigate the relationship between fenfluramine and brain antioxidant defense system in mature and aged animals. Rats aged 4 and 17 months were chronically treated with dl-fenfluramine, d-fenfluramine, or saline. Brain activity of superoxide dismutase and glutathione peroxidase was significantly affected by aging. Catalase activity was altered by the treatment. Total glutathione content and chemiluminescence in the brains were also altered by aging. Glutathione levels were altered as a function of the interaction between age and treatment. These findings suggest that treatment with d- or dl-fenfluramine results in alteration of the antioxidant system that could be exacerbated when associated with the aging process. © 1997 John Wiley & Sons, Inc.     

Sexual exhaustion in White New Zealand male rabbits of different ages

Sexual exhaustion was studied in hybrid White New Zealand rabbits of different ages, for this purpose six young rabbits from 6 to 12 months of age, and six adult rabbits of 14-20 months of age were selected. Sexually receptive females were taken to the male's cage, for a period of 4 min, if copulation was not performed, the observation was then considered finished. If the male mounted within this period of time, the mounted female was immediately replaced by another female and 4 min of exposure time to the male were reinitiated, and repetitions were conducted until the male that was being studied refused to mount a new female at which time the male was considered to be sexually exhausted. Young rabbits mounted and ejaculated 9-10 times before sexual exhaustion. Adult rabbits showed a fluctuation of between 6 and 8 mounts per ejaculations before refusing another mount. The statistical analysis with a Mann-Whitney U-test, showed that the Rank sum for group A was 57, while for group B was 21. The U-value was 0.0 and the adjusted Z -2.9943. A significant difference was observed between groups with a value of P=0.00275. In the present study it was demonstrated that there is an influence of age on sexual behavior of rabbits.     

Ventilatory functions of normal rats of different ages

1. Lung volume, respiratory mechanics and flow-volume curve were measured in 96 male Wistar rats weighing from 102 to 521 g. Their ages ranged from 31 to 137 days and therefore, most of them were in the rapidly growing phase. 2. Data except for functional residual capacity were obtained under conditions of artificial ventilation. 3. Total lung capacity and the fractions of lung volume of these animals were found to relate linearly with their body weights. 4. Most of the parameters concerning respiratory mechanics and flow-volume curve also changed generally in proportion to their body weights, but those standardized for lung volume were not constant but varied depending on the weights. 5. These results suggest that the mechanical properties of lungs of young rats are age-related and comparisons of ventilatory functions among those animals should be carefully done.     

Effects of taurine and verapamil on heart calcium in hamsters and rats

Heart calcium was measured in hamsters and rats following 30 days of drinking (i) tap water, (ii) taurine solution (T) or (iii) a taurine uptake inhibitor (GES). The regimes were duplicated in animals receiving verapamil (V). Heart calcium was reduced in both species by T + V; a comparable effect was obtained with GES alone; T alone had no effect. In the hamster, the GES effect was reversed by GES + V; V alone had no effect. In rats, the separate and combined effects of GES and V on heart calcium were identical. Possible mechanisms and underlying species differences are discussed.     

Effects of an anabolic steroid on reproduction in female rats

Mature female rats given food and water ad libitum and maintained under a lighting schedule of 12h light/12h dark were treated with boldenone undecylenate. Neither dosage nor duration of treatment had a significant effect on weight gain when compared to controls. All treated females were characterized by the absence of cyclic ovarian activity that continued for several weeks following termination of treatment. Long term reproductive performance was altered by a significant reduction in both conception rate and neonatal survival. Behavioral patterns were modified for several months following steroid withdrawal.     

Ultrastructural morphometry of parathyroid cells in rats of different ages

Summary Parathyroid glands of newborn to 1-year-old male Sprague-Dawley rats were fixed by perfusion or by immersion, and prepared for electron microscopy. Parathyroid glands fixed by immersion exhibited parenchymal cells with variable ultrastructure, indicating that these cells were in different stages of the proposed secretory cycle in parathyroid cells. In contrast, parathyroid cells of glands fixed by perfusion were uniform in ultrastructure, suggesting that all cells were in the same stage of secretory activity. Parathyroid glands of 3-, 4-, 6-, 8- and 10-week-old rats also were fixed by perfusion and analysed by electron-microscopic morphometry. These data demonstrated an increase in cell volume and in surface area of the membrane compartments concerned with parathyroid hormone secretion: these changes were not related to variations in serum calcium concentration. Both the qualitative observations and the quantitative data do not favour the idea of a secretory cycle in rat parathyroid cells.     

Morphofunctional characteristics of adrenal reactivity in rats of different ages

Ultrastructural peculiarities of the cortical and medullary substance of the adrenals have been studied in mature (8-month-old) and old (26-month-old) intact white male rats and in rats of the same age groups in 3 h after electrical stimulation of the hypothalamic ventromedial nuclei. By means of certain biochemical methods contents of hormones (corticosterone, adrenaline and noradrenaline) have been estimated, as well as that of cholesterin and ascorbic acid in blood and adrenal tissues. After the hypothalamus is stimulated in the mature rats, certain peculiarities in the adrenals reactivity are revealed; they demonstrate positive ultrastructural and functional correlation of secretory cells in the cortex and medulla and are characterized with hypertrophy of the nuclei, increased amount of polyribosomes, hypertrophied Golgi complex and canaliculi of the endoplasmic reticulum and increased contents of corticosteroids and catecholamines in blood. In the old rats after stimulation of the hypothalamus, certain unequal ultrastructural and functional peculiarities are revealed. They demonstrate both disturbance of the hypothalamic regulation of the adrenal function at ageing and decreased adaptive possibilities of the adrenal secretory cells at the subcellular level.     

粪便激素水平反映不同出生时期雄性布氏田鼠的繁殖策略

布氏田鼠是我国内蒙古草原的主要害鼠之一,具有明显的季节繁殖特征,不同季节出生个体可能具有不同的繁殖策略,但尚缺乏内分泌证据支持。本研究采用标志重捕法,连续监测大型自然围栏中不同年龄雄性布氏田鼠的繁殖状态和应激水平的季节变化,分析各年龄组雄鼠的繁殖发育策略。结果表明,越冬雄鼠可保持较高的睾丸下降率和睾酮水平至8月初;而部分5月生雄鼠的繁殖期睾酮水平较接近越冬鼠,但8月初已降至年内最低水平,而6月及以后出生雄鼠睾酮始终处于较低水平;这说明越冬鼠的繁殖状态可贯穿繁殖期始终,只有部分5月生雄鼠可能参与当年繁殖,而6月及以后出生雄鼠则不能在当年繁殖。越冬鼠皮质醇水平高于当年鼠,繁殖期高于非繁殖期,这可能是越冬鼠由于繁殖需要而保持较高应激状态,从而造成繁殖盛期后死亡率升高。这些结果说明,不同时期出生的雄性布氏田鼠具有不同的出生后性腺发育模式和繁殖策略,反映出生存与繁殖之间的权衡。     

Effects of taurine on the reactivity of aortas from diabetic rats

The effects of the semi-essential amino acid-like nutrient, taurine, on alterations in the reactivities of aortas from male rats with chronic streptozotocin-induced diabetes were examined under in vitro conditions. In the absence of taurine, the contractile responsiveness of endothelium-denuded aortic rings from diabetic rats to norepinephrine, but not KCl, was enhanced compared to controls. This effect of norepinephrine on the diabetic rat aorta appeared to be associated with increased release of intracellular calcium, influx of extracellular calcium and protein kinase C-mediated responses. Incubation of endothelium-denuded aortic rings with 10 mM, but not 5 mM, taurine for 2 h reduced the augmented contractile responses of the tissues from diabetic rats to norepinephrine close to control levels, and this was associated with inhibition of responses linked to the release and influx of calcium, and protein kinase C activation. Endothelium-dependent relaxation of aortas from diabetic rats to acetylcholine was depressed relative to controls. This effect of diabetes was ameliorated close to control levels by incubating the tissues with 10 mM, but not 5 mM, taurine for 2 h. Incubation of nondiabetic rat aortic rings with 45 mM glucose for 3 h caused enhancement of contraction of the vascular smooth muscle to phenylephrine and impairment of endothelium-mediated vasorelaxation to acetylcholine, as compared to control responses. Co-incubation of the tissues with 5-10 mM taurine concentration-dependently reduced the alterations in both contractile and relaxant responses caused by high glucose. Overall, the data suggest that taurine ameliorates or prevents vascular reactivity alterations in diabetes. Such an observation provides preliminary evidence for taurine's potential as a therapeutic agent for the prevention or amelioration of vascular disorders in diabetes.     

牛磺酸对Ⅱ型糖尿病大鼠血液流变学的影响

目的：探讨牛磺酸（taurine）对Ⅱ型糖尿病（diabetes mellitus,DM）大鼠血液流变学及氧化应激的影响。方法：将40只Wistar大鼠随机取10只为正常对照组（control组）、其余30只大鼠中取20只符合模型标准的大鼠随机分为糖尿病组（DM组）和牛磺酸治疗组（Tau组,采用20g/L牛磺酸生理盐水溶液治疗,200mg/kgbw）,前两组注射等体积的生理盐水溶液。8周后,测3组大鼠血浆葡萄糖、糖化血红蛋白、超氧化物岐化酶（SOD）、丙二醛（MDA）及血液流变学指标。结果：与对照组相比,糖尿病大鼠血糖、MDA及糖化血红蛋白明显升高,SOD活性降低,全血粘度、红细胞聚集指数、红细胞压积明显增大,红细胞变形指数减小;牛磺酸能明显降低糖尿病大鼠的血糖、MDA和糖化血红蛋白（P〈0.05或P〈0.01）,显著升高造模大鼠SOD（P〈0.01）;并且明显降低大鼠全血黏度（P〈0.05）、降低红细胞聚集指数（P〈0.05）,提高红细胞变性指数（P〈0.05）。结论：牛磺酸改善糖尿病大鼠的血液流变性可能与其提高大鼠的抗氧化能力有关,对防治糖尿病血管并发症有较好作用。     

Tissue reaction of rats of different ages to xerophagia

Studies have been made on the ionic and osmotic indices of the blood, as well as on the content of water and electrolytes in different tissues of rats from 2 age groups (adult animals over 90 days and 18-24 days old ones) in the course of water deprivation within 7 days. It was demonstrated that concentration of sodium in and osmolarity of the blood plasma increased earlier and to a greater extent in young animals as compared to adult ones. In most of the tissues investigated, these changes were accompanied by the increase in the content of electrolytes and water. In the subcutaneous tissue, accumulation of cations and dehydration were observed. Adult rats exhibited mainly ion-accumulating processes in all the tissues investigated, whereas young animals showed mainly shifts in water content of the tissues.