Increase In Noradrenaline Excretion Research Articles

Another chapter in the understanding of angiotensin-catecholamine interactions relevant to blood pressure control.

Another chapter in the understanding of angiotensin-catecholamine interactions relevant to blood pressure control.

Effect of the cannabinoid receptor-1 antagonist rimonabant on lipolysis in rats

The cannabinoid receptor 1 antagonist, rimonabant, reduces food intake and body weight, but contradictory findings have been reported as to whether the weight-reducing effect is fully accounted for by the reduced food intake or if rimonabant also mediates a lipolytic effect. In the present study, the effect on weight loss was studied in diet-induced obese rats after 3 days and 3 weeks of exposure to rimonabant, respectively. Induction of lipolysis was examined following acute administration and following 3 weeks of repeated dosing. Rimonabant-treated rats lost significantly more weight than their food-restricted controls. This effect was most pronounced in the beginning of the treatment period. No increase in lipolytic activity was found after 3 weeks of repeated dosing as measured by microdialysis in adipose tissue whereas acute administration of 10 mg/kg produced a significant increase in microdialysate levels of glycerol illustrating an acute stimulation of lipolysis. No equivalent increase in glycerol was, however, observed in vitro following incubation of isolated rat adipocytes with rimonabant. This finding excludes a direct lipolytic action of rimonabant on tissue level. Instead, administration of 10 mg/kg produced a significant increase in noradrenaline excretion in diet-induced obese rats, suggesting an increase in sympathoadrenal activity. In conclusion, the present study suggests an acute lipolytic effect of rimonabant mediated through activation of the sympathoadrenal system.

Conditioned reflex responses of the sympathetico-adrenal system to an aversive taste stimulus.

Studies were carried out on male and female rats in which the effects of isolated presentation of a conditioned stimulus (a saccharine solution) to which the animals had previously developed conditioned reflex taste aversion (RTA) on the level of urinary catecholamine secretion were determined. The studies showed that presentation of an aversive taste stimulus without reinforcement by a negative stimulus increased the levels of urinary adrenaline, noradrenaline, and dopamine secretion; this repeated, albeit more weakly, the effects of the negative reinforcement (angular acceleration) used for development of RTA. After presentation of the isolated aversive taste stimulus, the greatest increase in catecholamine excretion affected adrenaline, which indicates an anxiety state (fear). There was also a significant increase in noradrenaline excretion in these conditions. The accompanying increase in dopamine excretion in experimental and control animals showed this change to be largely nonspecific in nature, and to result from the experimental procedures. Isolated presentation of the conditioned taste stimulus elicited significantly greater increases in urinary catecholamine excretion in males than in females. It is suggested that the time for which the RTA is retained could be increased by activation of the sympathetico-adrenal system resulting from presentation of the nonreinforced taste stimulus which had acquired aversive properties.

An increase in noradrenaline excretion during prolonged mental task load.

To investigate the effects of prolonged mental work, urinary excretion of catecholamines and cortisol was measured in 18 human subjects from 9:30 to 17:00. On the "task day,' the subjects performed mental tasks during the morning (10:20-11:45) and afternoon sessions (13:00-17:00), otherwise taking chair rest. On the "control day,' the subjects took chair rest in the afternoon after performing mental tasks in the morning. In the morning session, urinary excretion of adrenaline during mental work increased greatly compared to that before the mental work. Mental work in the afternoon session also caused a marked increase in adrenaline excretion compared to the rest level in the afternoon on the control day. Cortisol levels in the first hour of the afternoon mental work were significantly higher than those during the corresponding time on the control day. Urinary excretion of noradrenaline during mental work in the morning session only increased slightly compared to that before the mental work. In the afternoon session, however, noradrenaline excretion during mental work on the task day was markedly elevated compared to that during the rest condition at the corresponding time on the control day. These findings suggest that prolonged exposure to mental work, but not short-term mental work, produces a marked increase in noradrenaline excretion in human subjects.

Phosphate and cyclic AMP excretion decreases during less than 12 hours of hypoxia in conscious rats.

Hypocapnia is known to have an antiphosphaturic effect that overcomes the phosphaturic effect of hypoxia. The objective of this study was to examine whether conscious rats exposed to acute hypoxia show a decrease in phosphate excretion due to the concomitant hypocapnia. Wistar rats weighing 200 g were exposed to hypoxia (inspired oxygen fraction = 0.10) or normoxia (inspired oxygen fraction = 0.21) for 6 h; and rats were alternately exposed to hypoxia or normoxia every 12 h for a total 36 h. Renal clearance and hormone studies were performed. Rats exposed to 6 h of hypoxia (n = 11) showed significant hypophosphaturia and decreases in absolute and fractional excretion of phosphate (0.38 +/- 0.10 microgram min-1, mean +/- SE, P < 0.0001 and 0.59 +/- 0.15%, P < 0.0001) as compared with normoxic rats (n = 11, 3.91 +/- 0.68 micrograms min-1 and 5.62 +/- 0.85%). In addition, nephrogenous adenosine 3',5'-cyclic monophosphate level per glomerular filtrate was significantly decreased (-0.87 +/- 0.64 nmol dL GF-1, P < 0.05) and plasma parathyroid hormone level was unchanged (45.2 +/- 9.5 pg mL-1) after 6 h of hypoxia as compared with normoxic rats (4.03 +/- 1.83 nmol dL GF-1 and 54.3 +/- 10.4 pg mL-1). A parallel increase in urinary noradrenaline and a decrease in dopamine excretion was observed in rats after 6 h of hypoxia. The decreased phosphate and adenosine 3',5'-cyclic monophosphate excretion during acute hypoxia were restored to normoxic levels by reoxygenation with 21% oxygen in the study of 12-h intermittent hypoxia. In summary, (1) hypoxia produced by inhalation of 10% oxygen for 12 h or less causes reduced phosphate and adenosine 3',5'-cyclic monophosphate (cAMP) excretion by spontaneously breathing rats; (2) these effects are reversed by reoxygenation and (3) hypoxia elicits a parallel increase in noradrenaline excretion and a decrease in dopamine excretion. These data suggest that renal adrenergic and dopaminergic systems play important roles in hypophosphaturia during acute hypoxia in conscious rats.

中高年鉄鋼労働者の労働負担 カテコールアミンとコルチゾールの尿中排せつ量からみて

To evaluate physical and mental workload in middle-aged workers, urinary excretion of catecholamines and cortisol and self-reported scores of fatigue, stress and arousal in middle-aged steel workers were compared with those in young steel workers. Noradrenaline excretion in daytime of the day-off was higher in middle-aged workers than that in young workers. In the work days, noradrenaline excretion during working hours increased in both age groups when compared with that in the day-off. The work-related increase in noradrenaline excretion was more evident in the middle-aged group than in the young group. Adrenaline excretion during working hours was greater in the middle-aged group than that in the young group, whereas the adrenaline value in the day-off was almost the same in the two age-groups. Age-difference was hardly observed in dopamine and cortisol excretion. These findings suggest that the workload in middle-aged workers was greater than that in young workers. However, self-reported scores of fatigue and stress in middle-aged workers were less than those in young workers, suggesting inconsistency between subjective score of workload and urinary levels of catecholamines. These age-related differences in urinary levels of noradrenaline and adrenaline were not so obvious in workers engaged in automated and mechanized work (vigilance task) when compared to workers engaged in less automated and less mechanized work. It is considered that factory automation might reduce the workload in middle-aged workers.

Catecholamine and cortisol excretion patterns in three-year-old children and their parents.

Urinary catecholamine and cortisol excretion was studied in a group of three-year-olds, their mothers and fathers during night rest, one day at home and one day at hospital. The stay in the hospital, which was part of a longitudinal study of the families, induced a pronounced rise in adrenaline excretion and a moderate increase in noradrenaline excretion in relation to the at-home level. Although the catecholamine excretion in relation to body weight was much higher in the children, the magnitude of the increase at the hospital was about the same in all the family members. The adrenaline excretion was also affected by the diverse conditions at the hospital and showed, for example, a marked decrease during lunch hour. The cortisol excretion at the hospital tended to be elevated only in fathers. On the average, mothers excreted about the same amount of adrenaline as the fathers at the hospital, but significantly more noradrenaline. In earlier studies males have shown a greater adrenaline output than females during achievement-demanding situations. The findings of this study were interpreted within the context of the specific challenge that the situation represented to the mothers. The mothers also excreted more noradrenaline in the at-home condition. Catecholamine and cortisol excretion levels within family members tended to be positively correlated, but the correlations were generally low.

Urinary excretion of noradrenaline in response to tilting in aged.

AbstractUrinary excretion of noradrenaline was measured after 1 h in supine and 1 h tilted head‐up 70 in 8 healthy persons 71–75 years of age. The lack of increase in noradrenaline excretion in response to tilting found in the investigation is probably a normal consequence of an altered reflex circulatory adaptation in this age group.

Catecholamines: thyroid function and the sexual cycle in rats.

ABSTRACT Investigations were performed on the daily urinary excretion of noradrenaline (NA), adrenaline (A) and 4-hydroxy-3-methoxymandelic acid (vanillylmandelic acid) and on the concentration of both amines in different areas of the central nervous system, in control, triiodothyronine (T3), and 131I-treated Wistar rats in order to gain some knowledge about the interrelation between thyroid function, sexual hormones and catecholamines. Cyclic variations were observed in NA excretion and in the excreted NA/A relationship in the three groups of animals. T3 increased NA excretion and decreased vanillylmandelic acid excretion in both sexes. A excretion did not show cyclic changes, nor was it influenced by the thyroid function. In the hypothalamus, there was an increase of NA in experimental hyperthyroidism. No changes were observed in 131I-treated animals. Progesterone stimulated the synthesis and/or depletion of NA storage while oestrogens had the reverse effect, making it also possible for the latter to potentiate the activity of phenylethanolamine-N-methyltransferase. The thyroid hormones inhibited monoamine-oxidase and extended the half life of catecholamines, a fact which was corroborated by the increase in NA excretion and the decrease in vanillylmandelic acid.

The excretion of catecholamines in rats during acute and chronic exposure to altitude.

The response of the sympathoadrenal medullary system in rats exposed to altitude has been assessed in terms of excretion of free noradrenaline (NA) and adrenaline (A) in the urine. Male Sprague–Dawley rats were either exposed acutely to simulated altitudes of 18 000 ft and 24 000 ft for 6 h or chronically to 18 000 ft for 5 weeks. Acutely exposed animals showed a considerable increase in the excretion of both catecholamines at 18 000 ft and 24 000 ft accompanied by a fall in body temperature. Acclimation to 18 000 ft by chronic exposure was achieved either by allowing the animals to reach the final altitude in stages during the 1st week, or by placing them directly at 18 000 ft. Body weight measurements confirmed that the second exposure condition was the more stressful. Although both groups showed an increase in NA excretion in the initial stages, only the second group exhibited an increase in A excretion. As the exposure continued, NA excretion returned towards sea level values. Preexposed animals maintained their body temperature at 18 000 ft and, when subsequently exposed to 24 000 ft for 6 h, did not excrete increased levels of NA or A. Increased activity of the sympathoadrenal medullary system appears to be involved only in the initial stages of acclimation to altitude.

Urinary excretion of adrenaline and noradrenaline in response to eserine before and after medullo-adrenalectomy in cats.

Removal of the adrenal medulla in cats was performed in two stages under sodium pentobarbital anesthesia. One mg eserine per kg of body weight was in-jected subcutaneously before and after medullo-adrenalectomy. Urine of 24-hour period was collected before and after injection of eserine and fluorimetrically analyzed for adrenaline and noradrenaline. The urinary excretion of adrenaline was increased significantly after administration of eserine in both intact and medullo-adrenalectomized cats. However, the urinary excretion of adrenaline in response to eserine in medullo-adrenalectomized cats was only 8 per cent of that in intact cats. The urinary excretion of noradrenaline was also increased after injection of eserine. As to the magnitude of increase in noradrenaline excretion there was no definite difference between those before and after medullo-adrenalec-tomy.

Catecholamine Excretion in Adreno‐Demedullated Rats Exposed to Gold after Chronic Guanethidine Treatment

AbstractAdreno‐demedullated rats subjected to a moderate cold exposure showed a significant increase in urinary excretion of noradrenaline (NA) and maintained their thermal equilibrium. Adrenodemedullated rats, chronically pretreated with guanethidine, however, failed to respond with an increase in NA excretion upon exposure to 3° C and all the animals died 7 days later following a fall in urinary NA. These results suggest that the survival of cold stressed adreno‐demedullated animals is dependent upon a peripheral secretion of NA.

THE INFLUENCE OF CHLORPROMAZINE ON THE CATECHOLAMINE EXCRETION OF NORMAL AND COLD ACCLIMATED RATS.

AbstractChlorpromazine was administered to normal rats placed at 30° and 20° C and to cold acclimated rats exposed to 30° and 2°. Treatment of the animals at 30° produced no increase in catecholamine excretion. However, rats placed at either 20° or 2° significantly increased their noradrenaline excretion, and to a lesser extent their adrenaline excretion, following chlorpromazine. These increases, also noted in adrenalectomized rats and associated with hypothermia, could be prevented by pretreatment with a ganglionic blocker. It is concluded that the increase in noradrenaline excretion is a result of a temporary hypothermia produced by chlorpromazine and originates from sympathetic nerve endings.

THE EFFECT OF COLD EXPOSURE ON THE CATECHOLAMINE EXCRETION OF ADRENALECTOMIZED RATS TREATED WITH RESERPINE.

AbstractAdrenalectomizad rats subjected to moderate cold exposure showed a significant increase in noradrenaline excretion in urine. Adrenalectomized rats, treated with reserpine. howevar, failed to respond with an increase in the noradrenaline excretion during cold stress. A fall in the noradrenaline excretion of the reser‐pinized animals was usually followed by death. These results suggest that reserpine treatment inhibits the synthesis of noradrenaline in vivo and that the survival of moderately cold stressed adrenalectomized animals is related to the secretion of noradrenaline.

Increase in noradrenaline excretion following activation of the vasomotor system during tilting in adrenalectomized patients.

Summary.The noradrenaline excretion figures in adrenalectomized patients were significantly increased during tilting head‐up + 750 as compared with the figures during recumbency, indicating that reflex activation of the vasomotor system causes an overflow of neurotransmitter into the circulating blood from where it can be partly recovered in the urine.