Effect of a tryptophan lead on the swine adrenal cortex reactivity and behavioral response to stress]

Behaviour and plasma corticosteroid levels were investigated in pigs preloaded with 50 to 200 mg/kg 1-tryptophan. The treatment did not influence reactions to frustation and had no effect on continuous avoidance responding. However the adrenal response to the stress of new environment concomitant with delivery of unavoidable shocks was decreased (fig. 1), as well as the behavioural response to a fear signal superimposed on a continuous avoidance paradigm (fig. 2). These results point out relatively specific psychotropic effects of a tryptophan load in pigs.     

Effect of alpha-tocopherol on adrenal cortex functions under stress]

alpha-Tocopherol has been studied for its effect on lipid peroxidation and steroidogenesis in the adrenal cortices of rat and rabbit under stress. The vitamin is shown to exert an inhibitory effect on the lipid peroxidation developing under chronic stress. A biphasic pattern of the alpha-tocopherol effect on the steroidogenesis in the adrenal cortex is established: a decrease in the release of the steroids under the acute stress and maintaining of their levels under the chronic stress. A conclusion is drawn about a potential alpha-tocopherol application to correct the adrenal cortex function under stress.     

Primary response mechanisms of the adrenal cortex in dogs to pain stress]

The adrenal cortex of dogs shows a drop in the glucocorticoid content 10--15 sec after the pain action in the presence of the free cholesterol level increase and its esterified form drop. The concentrations of hormones in the blood falls chiefly at the expense of protein bound hydrocortisone. The subsequent phase of the reaction (after 30--60 sec) is characterized by a considerable accumulation of the hormones by the gland. The level of free glucocorticoids significantly increases, the initial ratio of hydrocortisone and cortisone restores, and transcortin depot is filled up. The role of the adrenal and transcortine depot in realization of feedback mechanisms under stress is discussed.     

Effect of prolonged exhausting exercise on the adrenal cortex response to ACTH

Plasma cortison response of ACTH injection was studied in dogs under control conditions and after a prolonged exercise performed until exhaustion. Exercise induced a marked increase in plasma cortisol concentration but no significant differences were found in the level of plasma cortisol following ACTH injection between the control and post-exercise animals.     

Effect of disabling bacteroid proline catabolism on the response of soybeans to repeated drought stress

The aim of this study is to evaluate the contribution of bacteroidproline catabolism as an adaptation to drought stress in soybeanplants. To accomplish this, soybeans (Glycine max L. Merr.)were inoculated with either a parental strain of Bradyrhizobiumjaponicum which was able to catabolize proline, or a mutantstrain unable to catabolize proline. A large strain-dependentdifference in nodule number and size was observed. In orderto separate inoculant-dependent effects on nodulation from effectson bacteroid proline catabolism, plants inoculated with eachstrain were only compared to other plants inoculated with thesame strain, thus removing the observed inoculant-dependentdifferences in nodulation as a bar to interpretation of theresults. This experimental design allowed a comparison of thedrought penalty on yield for plants with parental bacteroidsand for plants with mutant bacteroids. The two results werethen compared to each other in order to evaluate the impactof the ability of bacteroids to catabolize proline on the responseto drought stress. When water stress was mild, soybean plants inoculated with bacteriaunable to catabolize proline suffered twice the percentage decreasein seed yield as did plants inoculated with bacteria able tocatabolize proline. However, when stress was severe there wasno significant effect of the ability of bacteroids to catabolizeproline on drought imposed decrease in seed yield. These resultssuggest that increasing the oxidative flux of proline in bacteroidsmight provide an agronomically significant yield advantage whenstress is modest, but that severe drought stress would probablyoverwhelm this yield benefit. Key words: N₂-fixation, proline dehydrogenase, drought stress     

Effect of 3-acetylpyridine on the functional activity of the adrenal cortex]

A reduction of blood corticosteroid content was observed in rats blood after the administration of 3-acetylpyridine. The rats given ACTH after 3-acetylpyridine showed a lesser elevation of corticosteroids in the blood and adrenal gland tissue than the intact animals; 3-acetylpyridine diminished the activity of dehydrogenase glucose-6-phosphate in the adrenal glands. The authors suggested that the action of acetylpyridine was realized at the adrenal gland level and consisted in inhibition of the NADP-H2 generation in the dehydrogenase systems.     

Effect of cholesterol administration on the state of the adrenal cortex in severe stress

The two weeks' effect of cholesterol on the rat adrenal cortex response under conditions of a severe stress was studied. In comparison with control, the degree of the gland activation and its alteration was found to decrease. It is suggested that the effect of cholesterol depends upon the action on the hypothalamus, and upon the adrenocortical tissue as well. The action of cholesterol on the adrenocortical tissue is bound with the cholesterol capacity to retard peroxydation reactions.     

Effect of N-acylethanolamines on adrenal cortex function

The possibility of NAE to take part in the regulation of the function of adrenal glands was studied. It was shown that two times NAE (18:0) injection in a dose 5 mg/kg of weight increased the content of 11-hydroxysteroids in blood of intact male rats. NAE caused the raise of the blood hormone content by 4 times under the immobilization stress. It is apparent that augment of stress response under the influence of NAE in vivo is explained by the activation of hypophysis-adrenal cortex system. In vitro NAE lowered steroidogenesis by near 40%. One can suggest that this decrease is caused by membranotropic properties of NAE.     

The sheep antibody response to repeated infection with Lucilia cuprina.

, , and 1992. The sheep antibody response to repeated infection with Lucilia cuprina. International Journal for Parasitology 22: 1169–1174. The specific serum antibody responses of sheep exposed to 10 consecutive infections of L. cuprina have been analysed by enzyme-linked immuno-sorbent assay and immunoblotting using monoclonal antibodies specific for sheep immunoglobulin isotypes. Recognition of a number of larval excretory-secretory products by IgM antibodies appeared to be non-specific. IgG₁ was the major antibody class stimulated by the infection protocol and marked increases in antibody to specific excretory-secretory antigens were observed. Three molecules of 35, 30 and 25 kDa were particularly recognized although the extent of recognition of these molecules varied considerably between individual sheep serum. A pooled serum composed of sera collected after five to seven infections significantly inhibited larval growth in in vitro cultures when compared to a sera pool consisting of sera collected both prior to infection and after infections 1 and 2. The degree of inhibition was greater when serum with high specific antibody titre was used.     

Effect of group and isolated rearing of white rats on their resistance to exposure to emotional stress]

The influence of isolated vs. group breeding on the sensitivity of higher nervous and vegetative functions to chronic stress effects was studied in 50 albino random-bred male rats. It has been found that group breeding of the animals (ten specimens in each cage) from the 12th to the 30th week of their life enhances their resistance to external stress factors which begin to take effect from the 17th week on. The effect is linked to the positive emotions produced by mutual contacts among the animals and their intensified motor activity. Isolated breeding of the rats (beginning with the 17th week of their life) makes them vulnerable to the action of stress situations. By the end of the investigation they exhibit clear symptoms of an early stage of neurogenic hypertension. The isolation evidently sets up a negative emotional background, reduces drastically the motor activity and lowers the animals resistance to extreme environmental influences.     

Effect of alpha-tocopherol on the adrenal reaction to cold stress

Adrenocortical function and the intensity of lipid peroxidation in the liver of animals fed the diet containing alpha-tocopherol (4 mg/day/rat for 7 days) and exposed to cold stress for 2, 5 and 20 hours were studied in vitro. It was established that alpha-tocopherol reduces the duration of the corticosterone secretion augmentation under cold stress but raises the sensitivity of the adrenals to ACTH. The action of the antioxidant correlated with its content in the tissues and inhibition of the cold-induced activation of lipid peroxidation.