Investigation of human and rat inactive renin in plasma and kidney.

Under an initial interval of immobilization stress in rats, reciprocal changes of plasma active and inactive renin were observed, suggesting activation of circulating inactive renin. Molecular weight (MW) studies revealed that this activation might proceed via a MW shift from inactive renin with MW of 50,000 to active renin of MW 43,000. In a later interval of stress, under stimulated renin secretion, a lower MW form (38,000) of active renin was released into the circulation.

Do the circulating neurohypophysial hormones affect basal or stress induced prolactin (PRL) release in male rats?

The action of acute administration of oxytocin (OXY), vasopressin (AVP) or its analog 1-deamino-8-D-arginine-vasopressin (dDAVP) on basal and stress induced PRL release in normal male rats and the effect of chronic injection of AVP on PRL stress response in AVP deficient rats were studied. The hormones (OXY, 600 ng min-1 per rat; AVP 6, 12 or 24 ng min-1 per rat and dDAVP 24 ng min-1 per rat) were infused to conscious rats via the jugular vein for 10 min and then the rats were immobilized under continuing the infusion for further 20 min. In parallel experiments arterial blood pressure (BP) was measured.

Repeated stress-induced activation of corticotropin-releasing factor neurons enhances vasopressin stores and colocalization with corticotropin-releasing factor in the median eminence of rats.

Stress-induced release of corticotropin-releasing factor (CRF) and vasopressin (AVP) was studied in rats by measuring the decline of CRF and AVP stores in the median eminence after blockade of fast axonal transport with colchicine (5 micrograms per rat intracisternally). Quantitative immunocytochemistry was used to detect changes in CRFi and AVPi in the external zone of the median eminence (ZEME) selectively. Immobilization stress induced a fast ACTH response to 1,000-2,000 pg/ml which was associated with a fall in both CRFi and AVPi of 34% during the first 30 min.

Effect of space flights on plasma hormone levels in man and in experimental animal.

An important increase of plasma hormone levels like insulin, TSH and aldosterone was observed in human subjects after space flights, however in the changes of plasma content of ACTH, cortisol, adrenaline and noradrenaline the individual variations were observed in relation to number and duration of space flight. For evaluation of the effects of these changes in plasma hormone levels on metabolic processes also the experiments with small animals subjected to space flights on a board of biosatellite of Cosmos series were running. An elevation of plasma levels of corticosterone, adrenaline, noradrenaline and insulin was found in rats after the space flights of duration from 7 to 20 days.

Activity of the sympathoadrenal system in cosmonauts during 25-day space flight on station Mir.

The activity of the sympathoadrenal system in cosmonauts was studied by measuring plasma and urinary catecholamines and their metabolites and conjugates. The appliance Plasma 02 was used for collecting, processing, and storing blood and urine samples from the cosmonauts during the course of a 25-day flight on board the station Mir. Plasma and urine concentrations of adrenaline (A), noradrenaline (NA), and dopamine (DA) as well as urinary levels of vanillylmandelic acid (VMA) and homovanillic acid (HVA), and plasma levels of catecholamine sulphates were determined before, during and after the space flight.

Neuroendocrine and immunologic effects of unemployment and job insecurity.

We prospectively followed a cohort of 354 blue-collar men and women, some of whom lost their jobs. Results show marked effects during the anticipatory and early unemployment phase on mental well-being, serum cortisol, prolactin, total cholesterol, HDL cholesterol, and phytohemagglutinin reactivity of lymphocytes. Most of these changes appear to be of short-term duration.

[Changes in circulating catecholamine levels in old rats under basal conditions and during stress].

The aim of the paper was to study the levels of circulating catecholamines in unrestrained cannulated rats under basal resting conditions and after exposure to two stressors. Catecholamines were determined radioenzymatically in 4-, 11-, 12-, 24-, and 28-month-old rats. Immobilization and exposure to ether vapors were used as stress models.

[The effect of chronic stress on the activity of the sympathetic-adrenomedullary system].

Plasma levels of adrenaline (ADR) and noradrenaline (NA) belong to the best parameters of activity of the sympatho-adrenomedullary system (SAS). Introduction of a sensitive radioenzymatic method for the determination of catecholamines in small volumes of plasma (0.05 ml) and observing conditions of stressless blood collection by means of an indwelling catheter made in possible to determine basal plasma catecholamine levels and their dynamics during stress.

Prolactin response to immobilization stress and hemorrhage: the effect of hypothalamic deafferentations and posterior pituitary denervation.

The roles of posterior and anterolateral connections to the mediobasal hypothalamus (MBH) as well as innervation of the posterior pituitary in the PRL response to immobilization (IMO) and hemorrhage (HEM) were studied by means of surgical isolation, performed 6-9 days before stress exposure. Male rats bearing indwelling tail artery cannulae subjected to 120-min IMO reached peak PRL secretion in 5-20 min. HEM of 25% elicited a significant rise of PRL levels.

Tolerance and cross-tolerance to stress-induced increases in plasma Met-enkephalin in rats with adaptively increased resting secretion.

Plasma concentrations of both native (pentapeptide plus its sulfoxide) and peptidase-derivable (trypsin followed by carboxypeptidase-B) Met-enkephalin showed brisk increases in response to the stresses of immobilization, hemorrhage, and electric footshock in conscious, freely moving, adult male rats. Daily exposure to 150-min periods of immobilization resulted in a maintained increase in baseline plasma concentrations of native Met-enkephalin 21.5 h after the sixth day and a further increase after 39 days.

Hormonal responses to hemorrhage and their relationship to individual hemorrhagic shock susceptibility.

The effect of differences in sympathoadrenomedullary and pituitary-adrenocortical responses of individual animals to 35% hemorrhage on severity of shock induction has been studied in unanesthetized unrestrained rats by measuring plasma concentrations of adrenaline (A), noradrenaline (NA), corticosterone (CS) and adrenocorticotropin (ACTH). The responses of A, CS and ACTH were related to the decrease of blood volume and mean arterial pressure (MAP), whereas plasma NA remained unchanged. Higher susceptibility to blood loss was characterized by more pronounced hemorrhage-induced increase in blood lactate concentration and plasma enzyme activities as well as lethal outcome of hemorrhagic shock.

Activation of the sympathoadrenal system in rats during hypokinesia.

The levels of plasma epinephrine (E) and norepinephrine (NE) were examined in rats exposed to hypokinesia in special adjustable cages for 1, 7 and 75 days. One day before the collection of blood an arterial catheter was inserted into the tail artery and blood samples were collected from undisturbed animals on next day at 8 a.m.

Prior immobilization stress alters adrenal hormone responses to hemorrhage in rats.

The effect of prior immobilization stress (IMO) on the plasma epinephrine (EPI), norepinephrine (NE), adrenocorticotropic hormone (ACTH), and corticosterone (CS) responses to acute hemorrhage was studied in conscious male rats with chronic catheters in tail artery, using two combinations of IMO and hemorrhage. IMO per se led to significant increases of EPI, NE, ACTH, and CS in all animals. Hemorrhage of 25% of estimated blood volume (EBV) performed immediately after 150 min IMO caused exaggerated release of EPI and NE, whereas CS remained unchanged at the level previously elevated by IMO.

Acetylcholinesterase and choline acetyltransferase activity in some hypothalamic nuclei under immobilization stress in rats.

Rats were subjected to acute immobilization (IMO) for 1 or 2 h and killed by decapitation. The hypothalamic supraoptic and paraventricular nuclei were isolated by dissection technique and the activity of acetylcholinesterase (AChE) and choline acetyltransferase (ChAT) was assayed. A period of 1 or 2 h of IMO resulted in a significant increase of AChE activity only in the supraoptic nucleus, while no change of ChAT activity occurred.

Changes in acetylcholine content, release and muscarinic receptors in rat hippocampus under cold stress.

The aim was to study the mechanism of the previously established decrease in acetylcholine (ACh) concentration in the rat hippocampus under cold stress. Male rats were exposed for 14 days to cold (5 degrees C) or kept (controls) at room temperature (24 degrees C). Acetylcholine content, release and muscarinic receptor binding were investigated in the hippocampus.

Effect of acute and repeated immobilization stress on food and water intake, urine output and vasopressin changes in rats.

In several experiments the rats were subjected to immobilization stress (IMO) for 150 min daily for 7 to 38 days and after each IMO they were placed into individual metabolism cages. A considerable decrease of food and water intake was found even after the first IMO and lasted up to the 7th IMO. This resulted in a decrease of body weight and of diurnal urine output, while the osmolality of urine increased.

Vasopressin and 1-deamino-8-D-arginine-vasopressin (DDAVP) reduce elevated plasma catecholamine levels in rats with hypothalamic deafferentation.

1. Anterolateral cut (ALC) of the medial basal hypothalamus (MBH) in rats produces an elevation of plasma catecholamine levels, especially of norepinephrine (NE), in unstressed animals and a more pronounced rise of plasma NE levels in response to immobilization (IMO). Animals with ALC have a destroyed corresponding vasopressin (AVP) and other peptides containing innervation of the median eminence and the posterior pituitary, resulting in the prevention of increased AVP secretion during the early intervals of IMO.

Opioid mu and delta and dopamine receptor number changes in rat striatum during stress.

The question whether acute and repeated immobilization stress is accompanied by changes in the number of opioid mu- and delta- -receptor and that of dopamine receptor in the rat corpus striatum was studied. The number of opioid mu- and delta-receptors as well as that of dopamine receptors was estimated in corpus striatum of rats subjected either to a single (acute) immobilization stress (IMO) for 150 min or to identical repeated stress exposure for 7 or 40 consecutive days. The number of mu-receptors was estimated by the use of 3H-dihydromorphine binding (an agonist) or 3H-naloxone binding (an antagonist).

Plasma and urine catecholamine levels in cosmonauts during long-term stay on Space Station Salyut-7.

The activity of the sympathetic adrenal system in cosmonauts exposed to a stay in space lasting for about half a year has so far been studied only by measuring catecholamine levels in plasma and urine samples taken before space flight and after landing. The device "Plasma 01", specially designed for collecting and processing venous blood from subjects during space flight on board the station Salyut-7 rendered it possible for the first time to collect and freeze samples of blood from cosmonauts in the course of a long-term 237-day space flight. A physician-cosmonaut collected samples of blood and urine from two cosmonauts over the period of days 217-219 of their stay in space.

Acetylcholine and its enzymes in some brain areas of the rat under stress.

A period of 1 or 24 h of cold stress (5 degrees C) resulted in a significant decrease of acetylcholine (ACh) concentration in the hypothalamus and hippocampus in rats. In the hippocampus the activity of the choline acetyltransferase (ChAT) was significantly increased after 24 h and that of acetylcholinesterase (AChE) after 1 and 24 h exposure to cold, whereas in the hypothalamus, AChE activity was found to be decreased, albeit only after 24 h exposure. Separate investigation of the dorsal and ventral hippocampus under 24 h of cold revealed that the ACh decreased in the dorsal hippocampus only, where no change in ChAT activity was observed.

Acetylcholinesterase activity in several hypothalamic and brain stem nuclei after acute and chronic immobilization stress in rats.

Acute and repeated immobilization stress increased acetylcholinesterase (AChE) specific activity in the nucleus supraopticus and median eminence of the rat and this increase was still present 24 hours after the 7th or 45th day of immobilization. The increase of AChE activity in those nuclei was probably related to the neuronal activation of the hypothalamic-pituitary axis during stress conditions. Acute and repeated immobilization was not accompanied by the change of AChE activity in A1 area and locus coeruleus.