Stress-induced increase in noradrenaline release in the rat hypothalamus assessed by intracranial microdialysis

Summary The hypothalamic microdialysis of conscious rats was used to investigate the effects of immobilization stress (20 min) on extracellular noradrenaline(NA) levels. The stress significantly increased NA levels relative to basal efflux by 106% and this elevation continued for 40 min after release from stress.     

Effect of repeated electroconvulsive shock on plasma noradrenaline and adrenaline in man

Summary The concentration of noradrenaline (NA) and of adrenaline (A) in plasma was measured before and 3, 30 and 60 min after single and repeated electroconvulsive shocks (ECS). Single ECS resulted in an activation of the sympathoadrenal medullary system; however, after the treatment had been repeated 4 times there was evidence of a diminished response of the peripheral sympathetic nervous system in comparison to the response to the first ECS.     

Interaction of cortisol and epinephrine in the regulation of leucine kinetics in man

To assess the interaction of the two major stress hormones epinephrine and cortisol in the regulation of leucine kinetics in man, epinephrine (50 ng/kg/min) was infused either alone or in combination with cortisol (2 micrograms/kg/min) into two groups of 6 postabsorptive normal male subjects during 180 min. Plasma leucine concentrations decreased by 28% (p less than 0.05) from baseline during epinephrine treatment (plasma levels 515 pg/ml); this was due to a decrease of leucine appearance (determined by 1-13C-leucine infusions) by 23% (p less than 0.025); leucine oxidation decreased by 29% (p less than 0.05). However, when plasma cortisol concentrations were elevated to supraphysiological levels (16.3 mumol/l) during epinephrine administration, the decreases of leucine plasma concentrations, appearance and oxidation were abolished. Plasma glucose and FFA concentrations were similarly elevated during both kinds of treatment. Since leucine appearance represents a measurement of total body protein breakdown and leucine disappearance into non-oxidative pathways reflects protein synthesis, the data indicate that plasma epinephrine concentrations during severe stress exert a protein anabolic effect in man which may counteract catabolic properties of elevated plasma cortisol.     

Acute heat/exercise stress in rats: effects on fluid and electrolyte regulatory hormones

Adult, male rats were exercised in the heat until hyperthermic exhaustion ensued. Plasma aldosterone levels were significantly (p less than 0.001) elevated after 8 min of exercise and remained increased throughout the exercise and recovery periods. Alternatively, plasma angiotensin I levels were unaffected during exercise, but increased significantly (p less than 0.001) during the recovery period. These rapid elevations in hormonal levels may be part of a sympathicoadrenal response to heat/exercise stress as well as an adaptational response to maintain plasma volume during and following exercise in the heat.     

Effects of neurochemical lesions restricted to spinal cord monoaminergic neurons on blood pressure and sympathetic activity of spontaneously hypertensive rats

Intraspinal (i.s.) injection of 6-hydroxydopamine or 5,7-dihydroxytryptamine in newborn spontaneously hypertensive rats (SHR) resulted, in the adult animal (30-week-old), in a marked decrease of spinal cord noradrenaline (NA) or 5-hydroxytryptamine (5-HT) levels, respectively. Since both neurotoxin- and vehicle-injected rats developed full hypertension and had similar plasma catecholamine concentrations, it is concluded that in SHR neither spinal cord NA nor 5-HT play a major role in development and maintenance of hypertension.     

The influence of cold or isolation stress on resistance of mice to West Nile virus encephalitis

The effect of cold or isolation stress on mortality rate and brain virus level were investigated in mice infected with West Nile virus (WNV). Exposure of mice for 5 min/day to cold water (1 +/- 0.5 degrees C) for 8-10 days resulted in 92% mortality as compared to 47% in control mice (p less than 0.001). Mice housed in individual cages (isolation stress) were also more susceptible to WN viral infection, as shown by increased mortality rate reaching 85% as compared to 50% in mice housed 6 per cage (p less than 0.01). Cold or isolation stress increased blood brain and spleen virus levels as early as 2 days after inoculation. After 8 days of isolation or cold stress, mice inoculated with WNV had 8.9 and 9.0 log10 plaque forming units in the brain, respectively, as compared to 6.9 in the control (p less than 0.01-0.001). Furthermore, lymphoid organs such as spleen and thymus showed severe mass loss. These data suggest that physical or non-physical stress situations enhance WNV encephalitis by accelerating virus proliferation and increase mortality in mice.     

Long-term depressor effects of catecholamine neuronal grafts in the third ventricle of the brain in normotensive rats

Summary Neuronal tissue containing A-6 group noradrenalin (NA) neurons of the locus ceruleus, or A-10 group dopamine (DA) neurons of the substantia nigra, was grafted into the third ventricle at the level of the preoptic-anterior hypothalamic region, in normotensive male rats. A significant and long-lasting depressor effect was shown in rats with either graft. In rats with an NA neuron-rich graft, plasma concentrations of arginine-vasopressin (AVP), plasma renin activity (PRA), and corticosterone (CS) decreased significantly, whereas in rats with a DA neuron-rich graft, AVP and PRA concentrations also decreased significantly but CS showed no significant change. Neither NA nor adrenalin in plasma changed significantly in rats with either graft.     

Long-term depressor effects of catecholamine neuronal grafts in the third ventricle of the brain in normotensive rats

Neuronal tissue containing A-6 group noradrenalin (NA) neurons of the locus ceruleus, or A-10 group dopamine (DA) neurons of the substantia nigra, was grafted into the third ventricle at the level of the preoptic-anterior hypothalamic region, in normotensive male rats. A significant and long-lasting depressor effect was shown in rats with either graft. In rats with an NA neuron-rich graft, plasma concentrations of arginine-vasopressin (AVP), plasma renin activity (PRA), and corticosterone (CS) decreased significantly, whereas in rats with a DA neuron-rich graft, AVP and PRA concentrations also decreased significantly but CS showed no significant change. Neither NA nor adrenalin in plasma changed significantly in rats with either graft.     

Differential inhibitory effects of noradrenaline upon insulin secretion by the isolated perfused pancreas of the rat

Summary Responses of basal and glucose-induced secretion phases of the isolated perfused pancreas of the rat to graded doses of noradrenaline (NA) are described. Maximal inhibition of basal secretion was achieved at [NA]=40, ng/100 ml; at [NA]=80 ng/100 ml, the 1st phase of glucose induced secretion was abolished; at [NA]=100 ng/100 ml the 2nd phase was abolished. At [NA]40 ng/100 ml basal secretion was less sensitive to NA inhibition than glucose induced output.Acknowledgment. The authors are most grateful to Mr J. Stevenson for advice upon and assistance with statistical analysis of data.     

Nitric oxide inhibition intensifies cold-restraint induced gastric ulcers in rats

Treatment 20 min beforehand with an inhibitor of nitric oxide (NO) synthesis, N^W-nitro-l-arginine methyl ester (L-NAME) (12.5, 25, 50 or 100 mg/kg, s.c.), dose-dependently intensified gastric glandular mucosal ulceration produced by cold-restraint stress. Hexamethonium (20 mg/kg) or atropine (1 mg/kg) pretreatment s.c. 20 min before stress strongly antagonised stress-evoked ulceration, as well as the ulcer-potentiating effects of L-NAME when either cholinoceptor antagonist was given concurrently with the NO inhibitor. Stress-induced mast cell degranulation was not worsened by L-NAME pretreatment. The findings suggest that NO could confer partial protection against stress-induced gastric ulcer formation; its activity is triggered off by the ulcerogenic mechanism of stress.     

Behavior and catecholamine levels: comparative study of gregarious insects, solitary insects, and those treated with carbon dioxide in Locusta migratoria (Insecta, Orthoptera)]

The dopamine (DA) and noradrenaline (NA) was measured in Locusta migratoria for 3 groups of individuals showing differences in their motility: gregarious are very active, solitary and animals in chronic treatment by CO2 (1 mn/day) show a very low motility. NA is present in small amounts (0,120-0,250 microng/g) in the 3 groups without significant differences. On the contrary, the quantity of DA is 5 times greater in gregarious than in the 2 other groups (1,78 and 0,31-0,39 microng/g). Thus it is suggested that DA is related to motility and must play its own role of a neurochormone, distinct from that of a metabolic intermediary between DOPA and NA. The question of a relationship between the metabolism of catecholamine and melanization is open.     

Effect of prostaglandin E2 (PgE2) on the biosynthesis and metabolism of noradrenaline (NA) in the isolated and perfused rabbit heart]

In isolated perfused rabbit heart, Pg E2 at concentrations ranging from 1.10(-8) to 1.10(-4) M has shown no significant action either on the biosynthesis or on the metabolism of NA. But it inhibited NA uptake, nevertheless this action was weak.     

Changes in the distensibility of the cat aortic arch induced by noradrenaline

Summary In the isolated preparation of the aortic arch of the cat, noradrenaline (NA) reduced at low pre-loads, and increased at high pre-loads, the arterial wall distensibility. For each dose of NA, the changes were directly related to the pressure level in the system.     

Influences of temperature change on the relaxation and amplitude inhibition by noradrenaline in the rabbit jejunum.

In the rabbit jejunum, the elevation of temperature within the range of 25-37 degrees C diminished the sensitivity to noradrenaline (NA) for both the relaxation and amplitude inhibition. The relaxation by NA was mainly mediated via adrenergic beta-receptors at 25, 30 or 37 degrees C. The amplitude inhibition was mediated via alpha-receptors at 37 degrees C, and both alpha- and beta-receptors at 30 or 25 degrees C.     

The influence of cold or isolation stress on resistance of mice to West Nile virus encephalitis

Summary The effect of cold or isolation stress on mortality rate and brain virus level were investigated in mice infected with West Nile virus (WNV). Exposure of mice for 5 min/day to cold water (1±0.5°C) for 8–10 days resulted in 92% mortality as compared to 47% in control mice (p<0.001). Mice housed in individual cages (isolation stress) were also more susceptible to WN viral infection, as shown by increased mortality rate reaching 85% as compared to 50% in mice housed 6 per cage (p<0.01). Cold or isolation stress increased blood brain and spleen virus levels as early as 2 days after inoculation. After 8 days of isolation or cold stress, mice inoculated with WNV had 8.9 and 9.0 log₁₀ plaque forming units in the brain, respectively, as compared to 6.9 in the control (p<0.01–0.001). Furthermore, lymphoid organs such as spleen and thymus showed severe mass loss. These data suggest that physical or non-physical stress situations enhance WNV encephalitis by accelerating virus proliferation and increase mortality in mice.     

Thermogenic response as the function of extravascular influx of infused noradrenaline

Summary The dynamic and static phases of the thermogenic response to i.v. infused noradrenaline (NA) do not reflect the arterial concentration of NA; according to the equation presented here they are a function of the influx rate.     

Isolation of human epidermal stem cells by adherence and the reconstruction of skin equivalents

The isolation of human epidermal stem cells is critical for their clinical applications. In the present study, we isolated three populations of epidermal keratinocytes according to their ability to adhere to collagen type IV: i.e., rapidly adhering (RA), slowly adhering (SA), and non-adhering (NA) cells. The aim of this study was to characterize RA cells and to investigate the possibility of using these cells for epidermis reconstruction. To identify RA cells, flow cytometric analysis was performed using anti-₆ integrin and anti-CD71 antibodies. RA cells express high levels of ₆ integrin and low levels of CD71, which are considered as markers of an epidermal stem cell nature. Furthermore, electron microscopy showed that RA cells are small and have a high nuclear to cytoplasmic ratio, whereas SA and NA cells have well-developed cellular organelles and abundant tonofilaments. Western blot analysis showed that RA cells are slow cycling and express p63, a putative epidermal stem cell marker, whereas SA and NA cells express c-Myc, which is known to regulate stem cell fate. To compare epidermal regenerative abilities, skin equivalents (SEs) were made using RA, SA, and NA cells. The epidermis constructed from RA cells was well formed compared to those formed from SA or NA cells. In addition, only SEs with RA cells expressed ₆ integrin and ₁ integrin at the basal layer. These results indicate that RA cells represent epidermal stem cells and are predominately comprised of stem cells. Therefore, the isolation of RA cells using a simple technique offers a potential route to their clinical application, because they are easily isolated and provide a high yield of epidermal stem cells.Received 2 July 2004; received after revision 20 August 2004; accepted 10 September 2004     

Evidence to support the hypothesis that ATP is a co-transmitter in rat vas deferens

Application of exogenous ATP or of noradrenaline (NA) produced responses in bisected rat vas deferens which mimicked the biphasic responses to nerve stimulation, and these actions were modified by nifedipine and verapamil in a manner similar to the modification of the 2 phases of the responses of the vas to nerve stimulation. It is proposed that sufficient evidence now exists to support the hypothesis that in this tissue, ATP is released along with NA from the motor nerves and that ATP may indeed be a co-transmitter.     

Effects of a definite stress on the enzyme activities in blood plasma in mice (author's transl)

The present study was designed to analyze the effects of a short term stress on the quantitative levels of alkaline phosphatase (AP), creatine phosphokinase (CK), aldolase (ALD), lactate dehydrogenase (LDH), and lactate dehydrogenase-1-isoenzyme (LDH 1) during 24 h after stress. For all the enzymes studied higher values for the activity were found due to stress in comparison to the activity level before the stress. The period during the 24 h after stress to reach maximum activity depends on the enzyme and in part on the sex of the animal.     

Effect of large mesencephalic-diencephalic lesions on the noradrenalin,dopamine and 5-hydroxytryptamine neurons of the central nervous system

Zusammenfassung Nach Ausführung von grossen symmetrischen mesencephalisch-dicncephalischen Läsionen in Ratten konnte mit Hilfe von biochemischen und histochemischen Methoden eindeutig festgestellt werden, dass die Dopamin (DA), Noradrenalin (NA) und 5-Hydroxytryptamin (5-HT) enthaltenden Nerventerminalen im Prosencephalon zu grossen aufsteigenden DA, NA und 5-HT Neuronsystemen gehören. Die Zellkörper dieser Neuronensysteme sind im Gehirnstamm lokalisiert. Dies deutet darauf hin, dass ein einzelnes NA Neuron Gebiete innervieren kann, die weit auseinander liegen, zum Beispiel auf der einen Seite im Cerebellum, auf der anderen im Prosencephalon.