Effect of Chronic Stress during Neonatal Ontogeny on Structural Organization of the Adrenal Gland in Hypertensive NISAG Rats

Structural organization of the adrenal gland was studied in 3-week- and 6-month-old hypertensive NISAG rats subjected to daily handling (10-min separation from mothers) on postnatal days 1-21. Neonatal handling reduces the stress-induced blood pressure rise in adult NISAG rats and modulates the structure of the adrenal cortex and medulla.     

Effect of Cold Stress in Early Postnatal Ontogeny on Blood Pressure and Heart Activity in Normo- and Hypertensive Rats

Cold stress in the early postnatal ontogeny caused permanent functional changes in the cardiovascular system, which were different in hypertensive NISAG and normotensive WAG rats. Stress led to elevation of blood pressure and overload on the left heart chambers in adult WAG rats postnatally exposed to cold. At the same time, postnatal exposure to cold stress attenuated functional disturbances typical of hypertensive NISAG rats.     

Effect of Chronic Stress during Early Postnatal Ontogeny on Structural Characteristics of the Myocardium and Glomerular Apparatus of the Kidneys in NISAG Rats

We studied structural characteristics of the myocardium and glomerular apparatus of the kidneys in 3-week- and 6-month-old male NISAG rats (hereditary stress-induced arterial hypertension) subjected to handling on days 1-21 of postnatal ontogeny. The animals were daily isolated from mothers for 10 min. Handling did not modulate the development of arterial hypertension and typical morphological signs in the myocardium and kidneys.     

Effect of enalapril injected in the early period of postnatal ontogeny on structure of adrenal glands in mature hypertensive NISAG rats

Blood pressure in 6-month hypertensive NISAG rats daily treated with enalapril in the early postnatal period was lower than in control rats. Enalapril produced significant morphological alterations only in the zona glomerulosa of the adrenal cortex. The volumes of this area and the corresponding endocrine cells were lower than in the control. Enalapril produced a delayed modifying effect on the structure of the adrenal zona glomerulosa by moderating hyperplasic alterations, which are characteristic of intact mature NISAG rats. __________ Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 141, No. 2, pp. 133–136, February, 2006     

Stress ulcer in normotensive and spontaneously hypertensive rats

Spontaneously hypertensive rats (SHR) and their normotensive progenitors, the Wistar-Kyoto (WKY) rats, were tested in the open-field arena and subsequently exposed to either cold-restraint stress or activity-stress. SHR rats were more active and judged less fearful in the open-field test. Changes in core body temperature, and adrenal and thymus weights did not differentiate between SHR and WKY rats in the cold-restraint procedure. A significant adrenal hypertrophy was observed for SHR rats in the activity-stress procedure. WKY rats were more susceptible to stress ulcer in both the cold-restraint and the activity-stress procedures. While running-wheel activity had been considered an important etiological variable for activity-stress ulcer, the lower activity demonstrated by the ulcer-prone WKY rats suggested that genetic variables might be more relevant to stress ulcer disease.     

Structure of Zona Reticularis of Adrenal Cortex in Hypertensive NISAG Rats

The structure of zona reticularis of the adrenal cortex in hypertensive NISAG rats was studied during the early, middle, and late periods of postnatal ontogeny. The detected morphological signs suggest that hypotrophic changes in zona reticularis of the adrenal cortex in hypertensive rats appeared before the onset of high blood pressure and accompanied the development of arterial hypertension in these animals. Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 146, No. 11, pp. 594-596, November, 2008     

Effect of cold stress in early postnatal ontogeny on blood pressure and heart activity in normo- and hypertensive rats

Cold stress in the early postnatal ontogeny caused permanent functional changes in the cardiovascular system, which were different in hypertensive NISAG and normotensive WAG rats. Stress led to elevation of blood pressure and overload on the left heart chambers in adult WAG rats postnatally exposed to cold. At the same time, postnatal exposure to cold stress attenuated functional disturbances typical of hypertensive NISAG rats. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 130, No. 12, pp. 660–664, December, 2000     

白松片对慢性应激抑郁模型大鼠行为学及血浆CORT、ACTH的影响

目的：观察白松片对慢性应激抑郁大鼠模型行为学和血浆CORT、ACTH含量的影响。方法：SD雄性大鼠28只随机分为空白对照组、模型对照组、氟西汀对照组及白松片试验组，选用慢性轻度不可预见性应激加孤养造模，观察各组大鼠敞箱实验和液体消耗等行为学指标变化，采用放射免疫方法检测大鼠血浆皮质醇(CORT)和促肾上腺皮质激素(ACTH)含量。结果：慢性应激抑郁大鼠体重增加缓慢，敞箱实验中的水平运动、垂直运动得分、清洁动作次数显著减少，中央格停留时间显著延长；糖水消耗明显下降，纯水消耗显著增多，而且其血浆皮质醇和促肾上腺皮质激素含量增加。氟西汀和白松片均显著改善慢性应激抑郁大鼠模型的行为学和神经内分泌变化。结论：慢性轻度不可预见性应激可使大鼠行为及神经内分泌发生异常改变，引起抑郁状态，白松片对此具有一定拮抗作用。     

慢性不可预知性应激刺激后大鼠行为学的改变

目的:建立长期慢性不可预知性应激刺激大鼠动物模型,观察大鼠在应激后行为学的改变。方法:雄性SD大鼠20只,5周龄,饲养3周后随机分为实验组和对照组,每组10只。实验组进行为期5周的随机应激刺激,建立慢性不可预知性应激动物模型,对照组不施加任何刺激,正常饲养。两组大鼠每周都要进行体质量测量、矿场行为学测验以及糖水偏好测试,将两组的测试结果进行比较。结果:两组大鼠在体质量方面无明显差异,而矿场实验,实验组与对照组从第14天就开始出现显著差异(t=-2.420,P=0.016);糖水测验两组出现显著差异则出现在21天时(t=5.854,P=0.000)。结论:大鼠的行为活动在长期慢性不可预知性应激刺激后明显改变,说明大鼠长期处在应激刺激下,正常的行为活动会出现障碍。     

Stress adaptation and adrenal activity in isolated and crowded rats

Socially reared male control rats (Co) were compared with crowded reared rats (Cr) and isolated reared rats (I). We assayed the adaptation to moderate stress (activity and defecation rate in open-field test) and to intensive stress sensitivity to restraint ulcer), so as the basal adrenal activity measuring basal values of corticosterone (R.I.A.) and fresh weight of adrenal and thymus glands. Results show a great lack of adaptation to moderate and intensive stress in Cr and I reared rats which leads to a decrease of activity variables, an increase of defecation rates and a high sensitivity to restraint ulcers. The effect of crowding conditions show higher values than isolation. We also found, in isolated and crowded reared rats, an increase in the adrenal function with great values for the basal secretion of corticosterone and atrophy of the thymus gland, besides which, crowded reared animals showed adrenal hypertrophy.     

Specific features in the behavior of rats with different genetic stability to stress

The effects of acute and chronic immobilization stress on the behavior of NISAG and outbred rats with different resistance to stress were evaluated. In the acute stress model, NISAG rats did not differ from stress-resistant outbred rats in the majority of the studied parameters. Chronic stress exhausted adaptive potential of NISAG rats, and their behavior became similar to that of rats with low resistance to stress. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 125, No. 4, pp. 420–424, April, 1997     

复方刺蒺藜苷对慢性应激抑郁模型大鼠行为学及海马CNTF表达的影响

目的：观察刺蒺藜苷对慢性应激抑郁大鼠行为学及海马CNTF表达的影响.方法：将大鼠随机分为正常组、模型组、复方刺蒺藜苷组、氟西汀组,采用慢性轻度不可预见性应激配合孤养复制抑郁模型.通过敞箱实验观察抑郁模型大鼠行为学改变并运用免疫组化和原位杂交方法探讨复方刺蒺藜苷对抑郁模型大鼠海马神经元细胞CNTF、CNTFmRNA表达的影响.结果：慢性应激抑郁大鼠敞箱实验中水平穿越格数、竖立次数、理毛时间有减少,中央格停留时间、粪便粒数均有增加.刺蒺藜苷和氟西汀可改善大鼠行为学变化.与模型组相比,复方刺蒺藜苷组大鼠海马神经元CNTF免疫反应阳性颗粒数目增多,神经元平均灰度值降低.结论：刺蒺藜苷能明显改善抑郁动物的各项行为学指标,增加海马CNTF、CNTF mRNA的表达具有抗抑郁作用.     

Structural Characteristics of Cardiomyocytes in the Right Atrium of NISAG Rats

Electron microscopy and stereomorphometric analysis of hypertrophic cardiomyocytes in the right atrium of NISAG rats revealed signs of activation of biosynthetic processes: increased relative volume of euchromatin (compared to Wistar rats), high density of nuclear pores, presence of large numerous Golgi complexes, and well-developed endoplasmic reticulum. The numerical density of secretory granules in the cytoplasm of cardiomyocytes in NISAG rats significantly surpassed that in Wistar rats. However, these granules in NISAG rats were smaller than in Wistar rats. The presence of numerous secretory granules and increased ratio of forming and dissolving structures suggest that this pool is characterized by high turnover rate, i.e., intensive synthesis and rapid elimination (consumption) of natriuretic peptide. Hypertrophy and hyperactivity of endocrine function in atrial cardiomyocytes of NISAG rats can be considered as a compensatory reaction to hypertension.     

Physiological and behavioral consequences of maternal and post-weaning protein restriction

Offspring of dams fed a protein restricted or control diet during gestation and lactation were weaned to the same diet and evaluated in the open-field just prior to puberty. No animals received preweaning handling. For 1, 2, 3 or 4 days, rearing and ambulation in the open-field were recorded. Fifteen minutes after testing, the animals were decapitated and plasma corticosterone assayed. Restricted animals ambulated and reared less and exhibited reduced basal and post-testing corticoid levels relative to controls. Although all animals reduced activity with repeated test experience, no concomitant reduction in circulating adrenal corticoids over the 4 days of testing was observed. These data suggest that maternal and post-weaning protein restriction, with calorie intake controlled, appears to reduce the animal's general responsiveness to environmental stimuli.     

Prenatal stress and emotional response of adult offspring

Pregnant dams were subjected to REM sleep deprivation during different stages of pregnancy. Pups were reared by their biological mothers and tested as adults for susceptibility to PTZ-induced convulsions, and ambulation and defecation in an open-field arena. Adrenal weights were taken at this time. Those animals whose mothers had been stressed during the first trimester showed a reduction in ambulatory behavior measured in the open field, and a reduction in adrenal weight after open-field exposure. Subjects exposed to prenatal stress (PNS) during the 2nd trimester showed an increased susceptibility to PTZ-induced clonic convulsions, and a reduction in adrenal weight after PTZ administration and open-field exposure. Finally, subjects exposed to PNS during the third trimester showed a reduction in susceptibility to PTZ compared with 2nd week PNS pups. The results showed different patterns of prenatal stress-induced behavioral and physiological changes, depending on the developmental stage in which the stress was applied.     

Comparative analysis of the persistence of a conditioned passive avoidance reflex in rats with different forms of inherited hypertension

The characteristics of anxiety behavior and reproduction of a conditioned passive avoidance reflex acquired in response to a single combination with an unconditioned aversive stimulus were studied in NISAG rats with inherited stress-sensitive arterial hypertension and spontaneously hypertensive SHR rats. SHR rats were characterized by hyperactive behavior, very low levels of anxiety, and poor reproduction of the conditioned reflex as compared with NISAG and control Wistar and WAG rats. Intermediate-anxiety NISAG rats showed no difficulties in acquiring and subsequently retaining the conditioned reflex. These differences in the ability to undergo single-combination learning in rats with different forms of hypertension suggest that memory processes are independent of elevated arterial blood pressure. The effects of the genetic characteristics of behavior and emotional status of these animals on memory are discussed. __________ Translated from Rossiiskii Fiziologicheskii Zhurnal imeni I. M. Sechenova, Vol. 92, No. 4, pp. 440–448, April, 2006.     

Open-field behavior, habituation and passive avoidance learning: Effect of ACTH and hydrocortisone on Normal and adrenalectomized rats

Exploratory behavior (GMA) and habituation rate (IH) were studied in an open-field situation in normal and adrenalectomized rats. Following this procedure the rats were subjected to passive avoidance learning (PA). Wide-spreading individual differences were observed in the exploratory behavior and the tendency of habituation of normal rats. As compared to the normal values, either the adrenalectomy which was performed 24 hr, 7 days and 28 days prior to the experiments or the ACTH and hydrocortisone treatment failed to modify the GMA and the IH significantly. An improvement of PA was found in the normal rats following ACTH and hydrocortisone treatment. In the adrenalectomized animals the hydrocortisone proved to be effective, whereas ACTH did not influence PA. No correlation was found between GMA, IH versus PA values and the influence of ACTH and hydrocortisone administration on these parameters. It is concluded that the direction of PA is unpredictable on the basis of the open-field test performed on R-Amsterdam strain of rats, and the effect of ACTH on passive avoidance learning is mediated through the adrenal glands.     

Memory deficit in passive-avoidance learning in bulbectomized Long-Evans hooded rats

Male and female Long-Evans hooded rats were subjected to either olfactory bulb damage or control surgery. Olfactory bulb removal resulted in increased mouse killing, increased irritability to handling, and increased open-field activity. In acquisition trials on a modified passive-avoidance apparatus, control animals habituated rapidly to the apparatus, while OB rats showed little evidence for habituation. All controls showed 24-hour retention of shock on the last acquisition trial, while OB rats showed the typical retention deficit, despite being given a behavioral alternative to withholding a response. The P-A deficit in OB rats appears to be a learning/memory deficit, not the result of heightened activity.     

Iron Content and Parameters of Blood Antioxidant Activity in Rats with Hereditary Arterial Hypertension during Experimental Myocardial Infarction

Plasma, lymph and myocardial Fe²⁺ contents and blood antioxidant activity were studied in hypertensive NISAG and normotensive Wistar rats with experimental myocardial infarction. In hypertensive rats, iron levels in plasma, lymph and myocardial tissue were increased throughout the experiment. In both strains iron content in the plasma during experimental myocardial infarction negatively correlated with blood antioxidant activity. In hypertensive NISAG rats this correlation persisted also during recovery. This attests to prooxidant effect of Fe²⁺ aggravating the course of myocardial infarction in NISAG rats.     

Activity of 11β-hydroxysteroid dehydrogenase in tissues of hypertensive NISAG rats

11β-Hydroxysteroid dehydrogenase activity in the kidneys of NISAG rats (rat strain with hereditary stress-induced arterial hypertension) was 1.5-fold higher than in WAG rats. An inverse relationship was observed in the liver of these animals. After stress exposure 11β-hydroxysteroid dehydrogenase activity remained unchanged in the kidneys of NISAG and WAG rats, but significantly increased in the liver of NISAG rats. Functional activity of 11β-hydroxysteroid dehydrogenase probably reflects the hypertensive state of NISAG rats. __________ Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 141, No. 1, pp. 35–37, January, 2006