11beta-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 11beta-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 11beta-hydroxysteroid dehydrogenase probably reflects the hypertensive state of NISAG rats.
In several seabirds, nutritional state of a nest-bound chick is negatively correlated with the activity of its hypothalamus-pituitary-adrenal (HPA) axis. Increased corticosterone (cort) secretion has been shown to facilitate changes in behavior that allow hungry chicks to obtain more food from parents. However, if parents are not willing/able to buffer their young from temporary food shortages, increased cort secretion could be detrimental to undernourished chicks. In a system where parents are insensitive to chick demands, low benefits and high costs of activation of the HPA-axis in hungry chicks should lead to a disassociation of the nutritional state of the young and the activity of its HPA-axis. We tested this novel hypothesis for the tufted puffin (Fratercula cirrhata), a seabird with intermittent provisioning of a nest-bound semi-precocial chick. We examined the HPA-axis activity of captive chicks exposed to the following: (1) a short-term (24 h) food deprivation; and (2) an array of prolonged (3 weeks) restrictions in feeding regimens. We found that in response to a short-term food deprivation chicks decreased baseline levels of cort and thyroid hormones. In response to prolonged restrictions, food-limited chicks exhibited signs of nutritional deficit: they had lower body mass, endogenous lipid reserves, and thyroid hormone titers compared to chicks fed ad libitum. However, baseline and maximum acute stress-induced levels of cort were also lower in food-restricted chicks compared to those of chicks fed ad libitum. These results support a major prediction of the study hypothesis that puffin chicks suppress HPA-axis activity in response to short- and long-term nutritional deficits. This physiological adaptation may allow a chick to extend its development in the nest, while eluding detrimental effects of chronic cort elevation.
It was investigated both melatonin blood level in the adult and old CBA-mice after immunization by sheep erythrocytes and the link between thymus and adrenal glands function in the old immunizated mice with high melatonin content in the pineal gland. It has been revealed that in the adult mice blood melatonin level was influenced by the phase changes in dynamic of immunization, namely raised significantly in 20 min with following suppression after 3 hrs and rehabilitation up to normal in 4 days. In the old mice fluctuations of melatonin level were impaired and characterized by gradually decrease in dynamics of immunization. The increase of melatonin content in pineal gland by administration of epithalamine improved the dynamics of fluctuations of thymic hormone and corticosterone level in the immunizated old mice.
The thymic serum factor (FTS) titer and corticosterone level in blood of adult and old CBA mice after immunization by T-dependent antigen was investigated. It has been revealed that in adult mice these indices influenced by phase changes in dynamics of immunization whereas in old mice fluctuations of FFS and corticosterone levels were monotonous. In both adult and old mice the correlation exists between thymic hormone and corticosterone. The increasing of thymic function by thymaline administration did not improve the dynamics of FTS titer and corticosterone level in immunized old mice.
The goal of this work was to find out to which degree the black coat color mutation nonagouti that appears in wild Norway rat in the course of breeding for the maintenance and enhancement of aggressiveness towards a human affects selected and other behavioral traits as well as stress reactivity and brain neurochemistry. Nonagouti rats displayed increased emotionality in the open-field and forced-swimming tests as compared to agouti animals, whereas there were no differences in anxiety estimated in the elevated plus-maze. Neither were there any differences in glucocorticoid reactions to a combined stressful procedure such as forced swimming. The dopamine content in the frontal cortex and striatum and noradrenaline content in the frontal cortex were increased in black rats as compared to gray rats. The result suggest that the nonagouti mutation in gray aggressive rats enhances the effects of selection for aggressiveness on some behavioral traits and brain catecholamine level.
Populations of many North American sea ducks are declining. Biomarkers may offer valuable insights regarding the health and fitness of sea ducks in relation to contaminant burdens. In this study we examined body condition, immune function, corticosterone stress response, liver glycogen levels and vitamin A status in relation to tissue concentrations of mercury, selenium and cadmium in female common eiders during the nesting period. The study was conducted in the eastern Canadian arctic during July, 2000. Hepatic mercury, selenium and renal cadmium concentrations ranged 1.5-9.8, 6.5-47.5 and 74-389 microg/g, dry wt, respectively. Mercury concentrations were negatively related to dissection body mass, heart mass and fat mass. Cadmium concentrations were negatively related to mass at capture and dissection mass after controlling for the mercury concentration-dissection mass relationship. Cell-mediated immunity was assessed by the skin swelling reaction to an injection of phytohemagglutinin-P, and was unrelated to metal concentrations. After adjusting the corticosterone concentration to account for the time between capture and sampling, there was a negative relationship between the residual corticosterone concentration and selenium. Liver glycogen concentrations were not significantly related to metal concentrations. Mercury concentrations were positively related to those of hepatic retinol and retinyl palmitate and the ratio of the retinol to retinyl palmitate in liver. They were negatively related to the ratio of plasma to liver retinol. Our findings do not indicate that exposure to metals may have adversely affected the health of these birds. They do, however, suggest that more research is required to elucidate mechanisms by which exposure to these metals could impact body condition.
The effects of neonatal administration ofverapamil, a calcium L-type channel blocker, on the stress and noradrenergic responses of hypothalamo-pituitary-adrenal (HPA) axis in adult female rats with anovulatory syndrome induced by neonatal androgenization have been studied. There was no adrenocortical response to an acute stress nor noradrenaline infusion in the 3rd brain ventricle in females with persistent estrus. Verapamil pretreatment completely restored the adrenocortical responses to normal level. No changes were found in studied parameters following treatment with verapamil alone. These results demonstrate possible involvement of calcium signalling in pathogenesis of the disorders of HPA function in adult female rats, induced by neonatal androgenization.
It was shown by using elaborated method of cell zinc quantitative determination that phase alterations in cell zinc content occurs during stress. Zinc accumulation in cells in the first phase was accompanied by the increase of blood corticosterone and corticotropine levels. A decrease of zinc concentrations in cells in second phase was accompanied by a decrease in the levels of these hormones. Zinc deficiency in cells was observed after adrenalectomy and insular apparatus function removal. Cell zinc deficiency correction was achieved in the first phase by adrenaline and prednisolone injections and in second one--by insuline administration. Positive correlation of the changes of zinc content in hippocampus and blood corticotropine level indicates possible functional connection between hippocampus and hypophysis.