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Abstract—We studied the effect of prenatal stress on the activity of glutathione-bound enzymes in the subcellular fractions of neurons and neuroglia of rat neocortex. The results of the study showed that prenatal stress causes changes in the activity of these enzymes in both neurons and neocortical neuroglia. These changes differ in the subcellular fractions of the studied cell populations. In the nuclei of neurons and neuroglia fraction, the activity of glutathione peroxidase increases. In the cytosol of neurons fraction, the activity of glutathione peroxidase decreases, while in the cytosol of neuroglia it grows. In neuronal mitochondria, the activity of glutathione peroxidase and glutathione transferase increases, while in the neuroglial mitochondria fraction, the activity of glutathione peroxidase decreases. It has been suggested that a change in the activity of these enzymes in the subcellular fractions of neurons and neuroglia is one of the causes for the resistance of the neocortex to the effects of prenatal stress. [ABSTRACT FROM AUTHOR]

To study the role of somatotropin (ST) in osmotic regulation of anadromous acipenserids, the dynamics of hormone concentration in blood serum of juvenile Russian sturgeon Acipenser gueldenstaedtii Brandt (age 4 months, average length 16.9 cm, average weight 17.1 g) during fish adaptation to hyperosmotic medium of 12.5‰ salinity (403 mOsm/l) was evaluated for the first time. During the first 24 h after the transfer of fish from freshwater to hyperosmotic medium, an increase of ST serum concentration (up to 2.06 ± 0.09 vs. 0.98 ± 0.03 pg/ml in control fish from freshwater) was observed. This increase occurs concurrently with an increase in blood serum osmolarity (up to 386.2 ± 4.0 mOsm/l vs. 218.5 ± 4.9 mOsm/l in control) resulting from the diffusion of water from the organism under new osmotic gradient, as well as with the period of morphofunctional remodelling of the osmoregulatory system corresponding to the transition of fish to hypoosmotic regulation. 24 h after the start of the experiment, fish that have shifted to hypoosmotic regulation display the adaptive decrease in osmolarity (aimed at maintaining the relative constancy of blood serum) and the ST concentration (down to 1.18 ± 0.16 pg/ml after 120 h, comparable with that in the control fish). It is concluded that during transition of juvenile Russian sturgeon to hypoosmotic regulation, ST becomes involved in morphofunctional remodelling of the osmoregulatory system concurrently with other components of this system. ST-immunopositive cells were revealed in the dorsal part of mesoadenohypophysis of Russian sturgeon juveniles by immunochemical method. [ABSTRACT FROM AUTHOR]

The activity of glutathione-associated antioxidant enzymes in subcellular fractions (cytosolic, mitochondrial, and cell nucleus fractions) was investigated in the liver of adult male Wistar rats born after prenatal stress was. Two groups of animals were studied in the experiment: (1) control group included - animals was born by intact mothers, and (2) prenatal stress group included animals whose mothers were subjected to immobilization stress in high-light conditions from the 15th to the 19th day of pregnancy. The activity of glutathione peroxidase (EC 1.11.1.9) in prenatally stressed animals decreased in the fractions of nuclei and mitochondria compared to the control group, while the activity of glutathione reductase (EC 1.8.1.7.) increased in the same subcellular fractions. The activity of glutathione transferase (EC 2.5.1.18) in prenatally stressed rats reduced in the cytosol and mitochondrial fractions as compared to control group. Redistribution of the antioxidant enzyme activity in the cytosol, the fraction of nuclei and the mitochondrial fraction of liver tissue may contribute to the formation of the pathological phenotype of prenatally stressed offspring.

We studied the effect of preliminary three-fold administration of dehydroepiandrosterone-sulphate (DHEA-S) on behavioral disturbance, induced by water-immobilization stress in high- and low-anxiety active rats. Active rats were selected from Wistar rats on the basis of T-maze testing. Active rats were then divided into the groups with high and low anxiety level after testing in elevated plus maze. We found that DHEA-S injections (3 mg/100 g, i.p.) had an anti-stress-like effect, as shown by a decrease stress corticosterone level in both groups of rats. DHEA-S also demonstrated an anxiolytic-like effects in high anxiety rats and anxiogenic-like effects in low anxiety rats. These results suggest that DHEA-S anxiolytic and anti-stress effects depend on the individual psycho-emotional status and baseline anxiety level.

The objective of this study was to ascertain the effect of dehydroepiandrosterone-sulphate (DHEA-S) on changes of anxiety level, induced by corticotropin-releasing hormone (CRH) injection. Active and passive rats were selected from Wistar rats on the basis of T-maze testing. Active rats were then divided into the groups with high (HA) and low anxiety (LA) level after testing in elevated-plus maze. Intranasal injection of CRH induced increase of anxiety level in the LA rats, while in HA rats it remained unchanged. DHEA-S exerted a moderate anxiolytic effect on the LA rats and sedative effect--on the HA rats. DHEA-S injection had no effect on anxiety level in passive rats that typically demonstrate high level of trait-anxiety and resistance to CRH. These results suggest that DHEA-S effect depends on the individual psycho-emotional status and responsiveness to CRH.

Corticoliberin (corticotrophin-releasing hormone, CRH) regulated of endocrine, autonomic and immune response to stress and is a mediator of anxiety in behavioral response. We studied the effect of corticoliberin on neuronal activity after microstimulation of olfactory cortex slices. Wistar rats strain were selected in T-maze labyrinth according to active and passive strategy of the adaptive behavior. The rats were exposed to water-immersions stress and after 10 days from their brain the olfactory cortex slices were prepared. The evoked focal potential were registered after perfusion with 0.1 mcM of CRH. It was revealed that in 60% of the slices of the active rats CRH induced the small decrease of excitatory amplitude but the increase amplitude inhibitory postsynaptic potential. In 40%, CRH induced the depression of synaptic transmission. Addition of CRH in incubation medium of the passive rat slices related, blockade the synaptic transmission.

Wistar rats strain with passive strategy of the adaptive behavior were selected in T-maze labyrinth. The rats were exposed to water-immerssions stress and after 10 days from their brain the olfactory cortex slices were prepared. The evoked focal potentials were registered in slices. It is shown that the amplitudes of the AMPA and NMDA EPSPs were reduced as compared to control (rats without stress). The amplitude of the GABABergic inhibitory postsynaptic potentiation was increased after stress. Additions of the corticotropin-releasing hormone (10(-10) M) in incubation medium result in reversible inhibition of synaptic transmission. Tetanic stimulation of the slices induced of the long-term posttetanic depression in 84 % slices and in 12 %--to the long-term posttetanic potentiation. It is indicates that the significant disturbances in synaptic transmission in slices. Thus the activation of the corticotrophinergic mechanisms in cortical structures not promots the removal of the rats depressive state with passive strategy of the adaptive behavior induced by inescapable stress.

Active as well as passive Wistar rats were subjected to a single water-immersion action that gave rise signs of poststressor depression in them. Administration of CRH-R1-receptor peptide blocker astressin prevented development of behavioural deficiency in active rats and did not affect behaviour of passive rats. This suggests that the corticoliberin receptor blockers are only effective for treatment of poststressor depressions in individuals with initially behavioural strategy.

A single intranasal injection of CRH alters adaptive behavior only in active rats. In particular this procedure results in increase of their behavioral passivity and reduction of psychomotor responsiveness. This neurohormone causes the same effect in active rats being injected by means of the same routine 20 days after animals have been exposed to a single water-immersion stress. But this effect of CHR is not observed after injection of the neurohormone to depressed animals in the stress-restress paradigm. Passive rats, intact or depressed, do not show any behavioral changes, while active ones develop signs of depression after repeated CRH intranasal injection.

Animals with active and passive behavioral strategy were selected among male Wistar rats by testing them in the T-maze. Using the results of rats testing in T-maze index of behavioral activity and index of behavioral passivity were calculated. The development of post-stress psychopathology and ils correlation with initial behavioral strategy were studied under water-immersion stress conditions consiclering individual alteration of adaptive behavior. Two paradigms were used--one time trial (stress) and two times trial (stress-restress). It was found that active and passive rats being subjected to inescapable aversive exposure develop different types of post-stress depression and only passive animals show the signs of posttraumatic stress disorder.

Original behavioral strategy is an important prerequisite for the pathogenesis of post-stress psychopathologies. Heterogeneity of these pathologies depends on the functional activity of hypophyseal-adrenocortical system.

The 3-month old SHR differ from the WKY rats in that the former have an increased osmolality, concentration of albumins, activity (but not the concentration) of sodium and a reduced activity of potassium. The shifts in the albumins concentration occur, mainly, on account of the amino acid phenylalanine. The gradient increase of the sodium and potassium concentration between the plasma and muscular tissue in followed by a slight hyperpolarisation of the muscle fibers, a drop in the lability and a increase in pO2. The above shifts of homeostatic parameters were not revealed in the SHR and WKY rats of 1.5 and 6.0 months of age.

The dynamics of distribution of potassium and sodium among the blood plasma and the tissues (muscle and liver) was studied in Wistar rats at an artificial increase of the potassium content in the blood. After administration of 1.25% solution of potassium chloride into the stomach (5 ml/100 g), into the liver portal vein (0.5 ml/100 g), and into femoral vein (0.1 ml/min during 45 min), the changes of potassium and sodium contents were opposite in the blood plasma and in the tissues under study. The maximal shift of these ions concentration in the plasma and tissues occurs sooner after administration of potassium directly into the blood. In continuous administration of the solution the potassium concentration reaches 10.8 mM/l in the blood plasma and returns to normal values within 2 hrs after cessation of the administration. Therefore, the redistribution of potassium between extra- and intracellular fluid plays a major role in restoration of the potassium homeostasis.