Thyroid hormone-catecholamine interrelationships during exposure to cold

1981 ◽  
Vol 97 (1) ◽  
pp. 91-97 ◽  
Author(s):  
H. Storm ◽  
C. van Hardeveld ◽  
A. A. H. Kassenaar
Keyword(s):  
Nervous System ◽  
Plasma Concentration ◽  
Thyroid Hormone ◽  
Sympathetic Nervous System ◽  
Plasma Levels ◽  
Surgical Procedure ◽  
Exposure To Cold ◽  
Basal Plasma ◽  
Sympathetic Nervous

Abstract. Basal plasma levels for adrenalin (A), noradrenalin (NA), l-triiodothyronine (T3), and l-thyroxine (T4) were determined in rats with a chronically inserted catheter. The experiments described in this report were started 3 days after the surgical procedure when T3 and T4 levels had returned to normal. Basal levels for the catecholamines were reached already 4 h after the operation. The T3/T4 ratio in plasma was significantly increased after 3, 7, and 14 days in rats kept at 4°C and the same holds for the iodide in the 24-h urine after 7 and 14 days at 4°C. The venous NA plasma concentration was increased 6- to 12-fold during the same period of exposure to cold, whereas the A concentration remained at the basal level. During infusion of NA at 23°C the T3/T4 ratio in plasma was significantly increased after 7 days compared to pair-fed controls, and the same holds for the iodide excretion in the 24-h urine. This paper presents further evidence for a role of the sympathetic nervous system on T4 metabolism in rats at resting conditions.

Neonatal hyperthyroidism: effects on sympathetic responses to stress in adult rats

1983 ◽  
Vol 245 (1) ◽  
pp. R95-R99
Author(s):  
R. McCarty ◽  
R. F. Kirby ◽  
P. C. Brunjes
Keyword(s):  
Nervous System ◽  
Sympathetic Nervous System ◽  
Plasma Levels ◽  
Acute Stress ◽  
Male Rats ◽  
Adult Rats ◽  
Basal Plasma ◽  
Repeated Sampling ◽  
Neonatal Hyperthyroidism ◽  
Sympathetic Nervous

Treatment of developing rats with thyroid hormone results in accelerated maturation of sympathetic and adrenal medullary responses to reflex activation of central sympathetic outflow. In this study, we examined the effects of neonatal hyperthyroidism on the responsiveness of the sympathetic nervous system of adult rats to acute stress. Hyperthyroidism was produced in Long-Evans hooded rats by injections of thyroxine (neo-T4, 1 mg/kg body wt) on postnatal days 1-4. Littermate controls received injections of vehicle only. In adulthood, male rats of the two groups were prepared with chronic tail artery catheters to allow repeated sampling of blood and direct measurements of mean arterial pressure (MAP, mmHg) and heart rate (HR, beats/min). Two days after surgery, rats were stressed by exposure to 1 min of inescapable foot shock (2.0 mA, 0.6-s duration, every 6 s). The activity of the sympathetic nervous system was assessed by measuring plasma levels of norepinephrine (NE) and epinephrine (E). Basal plasma levels of NE and E and resting MAP did not differ between neo-T4 and control rats. However, basal HR was elevated in neo-T4 rats. Footshock-induced increments in plasma levels of both catecholamines were greater in neo-T4 compared with control rats even though behavioral responses to footshock were similar across groups. However, neo-T4 rats were more active when tested in an open field on each of 3 consecutive days. These findings indicate that neonatal treatment with T4 results in hyperresponsiveness of the sympathoadrenal medullary system to acute stress that persists into adulthood.

Sympathetic nervous system and blood pressure maintenance in the Brattleboro DI rat

1986 ◽  
Vol 250 (5) ◽  
pp. R770-R775 ◽  
Author(s):  
J. L. Williams ◽  
M. D. Johnson
Keyword(s):  
Blood Pressure ◽  
Nervous System ◽  
Sympathetic Nervous System ◽  
Bolus Injection ◽  
Plasma Concentrations ◽  
Sympathetic Function ◽  
Unstressed State ◽  
Basal Plasma ◽  
Sympathetic Nervous

Experiments were performed to determine the functional role of the sympathetic nervous system (SNS) in blood pressure regulation in Brattleboro diabetes insipidus (DI) rats and to determine the effects of synthetic arginine vasopressin (AVP) on sympathetic function in DI rats. The experiments were conducted in male age-matched Long-Evans (LE) and DI rats in the conscious unstressed state. Mean arterial pressure (MAP) and heart rate were similar in conscious unstressed LE and DI rats, but basal plasma concentrations of norepinephrine (NE) and epinephrine (E) were elevated in DI rats compared with LE rats. An intra-arterial bolus injection of hexamethonium (30 mg/kg) resulted in greater reductions of MAP in DI rats (-62 +/- 5 mmHg) than in LE rats (-42 +/- 7 mmHg; P less than 0.05). Administration of AVP to DI rats by osmotic minipump reduced plasma NE concentration in DI rats to a level not different from that in LE rats, but E concentration remained elevated. AVP administration to DI rats also reduced the hexamethonium-induced fall in MAP in these animals (-47 +/- 7 mmHg) to a level not different from that in LE rats. We conclude that the SNS plays a greater role in blood pressure maintenance in conscious DI rats than in LE rats and that AVP administration can normalize plasma NE concentration and the contribution of the SNS to blood pressure maintenance in these animals.

Hyperresponsiveness of monoaminergic mechanisms in DOCA/NaCl hypertensive rats

1985 ◽  
Vol 249 (1) ◽  
pp. H71-H79 ◽  
Author(s):  
Y. F. Chen ◽  
S. Nagahama ◽  
S. R. Winternitz ◽  
S. Oparil
Keyword(s):  
Nervous System ◽  
Sympathetic Nervous System ◽  
Plasma Norepinephrine ◽  
Developmental Phase ◽  
Plasma Prolactin ◽  
Hypertensive Rats ◽  
Basal Plasma ◽  
Sympathetic Nervous ◽  
Monoaminergic Mechanisms

To examine the role of the sympathetic nervous system in the development of deoxycorticosterone acetate (DOCA)/NaCl hypertension and to test the hypothesis that the responsiveness of the sympathetic nervous system to stress is enhanced during the developmental phase of hypertension in this model before resting sympathetic activity becomes increased, DOCA/NaCl-treated rats and uninephrectomized control animals were studied after 3, 7, 14, and 28 days of treatment. Basal plasma norepinephrine and epinephrine in conscious, unrestrained resting DOCA/NaCl-treated rats were the same as in controls at 3, 7, and 14 days but were significantly elevated at 28 days of treatment. Ganglionic blockade resulted in a significantly greater decrease in mean arterial pressure in DOCA/NaCl rats than in controls at 14 and 28 days of treatment. At 14 days, DOCA/NaCl rats exhibited significantly greater increments in plasma norepinephrine and epinephrine following cold stress than did H2O controls. Basal plasma prolactin levels were elevated and release of dopamine from isolated superfused mediobasal hypothalami reduced in 28-day DOCA/NaCl hypertensive rats. These results indicate that sympathetic nervous system activity increases progressively during the development of DOCA/NaCl hypertension and that the sympathoadrenal system is hyperresponsive to environmental stress even early in the course of DOCA/NaCl treatment and suggest that hypothalamo-hypophyseal function is altered in this model of hypertension.

Neurovascular Role of Sympathetic Nervous System and Beta-Adrenoceptor Polymorphisms in Obesity and Hypertension

2008 ◽  
Vol 4 (2) ◽  
pp. 121-130 ◽  
Author(s):  
Kazuko Masuo ◽  
Gavin Lambert ◽  
Hiromi Rakugi ◽  
Toshio Ogihara ◽  
Murray Esler
Keyword(s):  
Nervous System ◽  
Sympathetic Nervous System ◽  
Beta Adrenoceptor ◽  
Sympathetic Nervous

scholarly journals Pathophysiology of Resistant Hypertension: The Role of Sympathetic Nervous System

2011 ◽  
Vol 2011 ◽  
pp. 1-7 ◽  
Author(s):  
Costas Tsioufis ◽  
Athanasios Kordalis ◽  
Dimitris Flessas ◽  
Ioannis Anastasopoulos ◽  
Dimitris Tsiachris ◽  
...  
Keyword(s):  
Nervous System ◽  
Sympathetic Nervous System ◽  
Resistant Hypertension ◽  
Antihypertensive Treatment ◽  
Treatment Options ◽  
Treatment Resistance ◽  
Obstructive Sleep ◽  
Cardiovascular Morbidity And Mortality ◽  
Sympathetic Nervous

Resistant hypertension (RH) is a powerful risk factor for cardiovascular morbidity and mortality. Among the characteristics of patients with RH, obesity, obstructive sleep apnea, and aldosterone excess are covering a great area of the mosaic of RH phenotype. Increased sympathetic nervous system (SNS) activity is present in all these underlying conditions, supporting its crucial role in the pathophysiology of antihypertensive treatment resistance. Current clinical and experimental knowledge points towards an impact of several factors on SNS activation, namely, insulin resistance, adipokines, endothelial dysfunction, cyclic intermittent hypoxaemia, aldosterone effects on central nervous system, chemoreceptors, and baroreceptors dysregulation. The further investigation and understanding of the mechanisms leading to SNS activation could reveal novel therapeutic targets and expand our treatment options in the challenging management of RH.

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