Effects of thyroid hormones and cold exposure on turnover of norepinephrine in cardiac and skeletal muscle

Tedesco, Joseph L.; Flattery, K. V.; Sellers, E. A.

doi:10.1139/y77-073

Cited by 29 publications

(9 citation statements)

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“…Noradrenaline turnover rate was shown to increase after thyroidectomy (Tu & Nash, 1975;Tedesco, Flattery & Sellers, 1977) or hypophysectomy (Landsberg & Axelrod, 1968), and an increased tonic release of the neurotransmitter may down-regulate postsynaptic receptors (Raff, 1976). This mechanism, however, cannot explain the present findings.…”

Section: Discussioncontrasting

confidence: 66%

The Influence of Hormonal and Neuronal Factors on Rat Heart Adrenoceptors

Kunos

Mucci

O’Regan

1980

British J Pharmacology

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1 The influence of hormonal and neuronal factors on adrenoceptors mediating increased cardiac force and rate of contraction were studied in rat isolated atria. The pharmacological properties of these receptors were deduced from the relative potencies of agonists and from the effects of selective aand /-adrenoceptor antagonists. The numbers and affinities of a-and /-adrenoceptors were also determined by radioligand binding to ventricular membrane fragments. 2 Hypophysectomy reduced the inotropic potency of isoprenaline and increased the potency of phenylephrine and methoxamine in left atria. The effect of phenylephrine was inhibited by propranolol less effectively and by phentolamine or phenoxybenzamine more effectively in hypophysectomized than in control rats. The difference in block was smaller at low than at high antagonist concentrations. Similar but smaller changes were observed for chronotropic responses of right atria. 3 The decreased /-and increased a-receptor response after hypophysectomy was similar to that observed earlier in thyroidectomized rats (Kunos, 1977). These changes developed slowly after hypophysectomy (>2 weeks), they were both reversed within 2 days of thyroxine treatment (0.2mg/kg daily), but were not affected by cortisone treatment (50 mg/kg every 12 h for 4 days). 6 These results indicate that thyrotropin or steroids do not contribute to the reciprocal changes in the sensitivity of cardiac xl-and /-adrenoceptors in altered thyroid states. These thyroid hormonedependent changes are probably due to a parallel, reciprocal change in the numbers but not the affinities of al-and /3-adrenoceptors. Reciprocal regulation of cardiac alj-and P-adrenoceptors by thyroid hormones requires intact sympathetic innervation but not the presence of normal stores of the neurotransmitter.

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Section: Discussioncontrasting

confidence: 66%

The Influence of Hormonal and Neuronal Factors on Rat Heart Adrenoceptors

Kunos

Mucci

O’Regan

1980

British J Pharmacology

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“…Acute cold exposure increases NE turnover in a variety of tissues in addition to heart and IBAT, including pancreas, lung, skeletal muscle, spleen, and kidney (10)(11)(12)29); in other tissues, such as liver, intestine, and submandibular gland,3 the changes in NE turnover with cold are minimal, if present at all (10,11). Of all tissues studied only IBAT demonstrated (Figs.…”

mentioning

confidence: 90%

Effect of Diet and Cold Exposure on Norepinephrine Turnover in Brown Adipose Tissue of the Rat

Young¹,

Saville²,

Rothwell³

et al. 1982

J. Clin. Invest.

336

153

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A B S T R A C T Brown adipose tissue (BAT)is an important site of adaptive changes in thermogenesis in the rat. The sympathetic nervous system, which richly supplies BAT, is thought to play an important role in the regulation of BAT thermogenesis because catecholamines stimulate and beta adrenergic blocking agents inhibit oxygen consumption in this tissue. The present studies were carried out to assess directly sympathetic activity in BAT in response to cold exposure and to changes in dietary intake, both of which alter heat production in the rat. Sympathetic activity was determined from the rate of norepinephrine (NE) turnover in interscapular brown adipose tissue (IBAT) after preliminary experiments validated the use of NE turnover techniques in IBAT. Acute exposure to 4°C increased NE turnover in IBAT 4-to 12-fold compared with ambient temperature controls, depending upon the interval over which the turnover measurement was made, while in the heart NE turnover doubled in response to the same cold stimulus. In animals exposed to cold continuously for 10 d before study, NE turnover measurements in IBAT and in the heart were elevated comparably to those obtained during acute exposure. Alterations in feeding were also associated with changes in NE turnover in IBAT. Fasting for 2 d decreased NE turnover in IBAT (-35% from 29.2±4.2 ng NE/h to 18.9±5.9) and in heart (-52%). In animals fed a "cafeteria" diet, a model of voluntary overfeeding in the rat, NE turnover was increased in both IBAT (+108% from 24.8±4.5 ng NE/h to 51.7±6.8) and heart (+66%). Because ganglionic blockade exerted a greater effect on NE turnover in IBAT in cafeteriafed rats than in controls, the increase in NE turnover in IBAT with this overfeeding regimen reflects enhanced central sympathetic outflow. Thus NE turnover techniques can be satisfactorily applied to the

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“…Consumption of a goitrogenic diet (LID supplemented with PTU) increased NE turnover in thyroid as well as heart. The stimulus for these responses likely represents a combination of both iodine deficiency and hypothyroidism, since hypothyroidism is widely recognized to stimulate sympathetic activity in human subjects (12,29) and in peripheral tissues of experimental animals (2,21,36,38).…”

Section: Discussionmentioning

confidence: 99%

Sympathetic nervous system activity in rat thyroid: potential role in goitrogenesis

Young

Burgi-Saville²,

Bürgi³

et al. 2005

American Journal of Physiology-Endocrinology and Metabolism

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Young, James B., M. Elizabeth Bü rgi-Saville, Ulrich Bü rgi, and Lewis Landsberg. Sympathetic nervous system activity in rat thyroid: potential role in goitrogenesis. Am J Physiol Endocrinol Metab 288: E861-E867, 2005. First published December 7, 2004; doi:10.1152/ajpendo.00292.2004.-The role of sympathetic innervation in regulation of thyroid function is incompletely understood. We, therefore, carried out studies in rats utilizing techniques of norepinephrine turnover to assess thyroid sympathetic activity in vivo. Thyroidal sympathetic activity was increased 95% by exposure to cold (4°C), 42% by chronic ingestion of an iodine-deficient diet, and 32% in rats fed a goitrogenic diet (low-iodine diet supplemented with propylthiouracil). In addition, fasting for 2 days reduced sympathetic nervous system activity in thyroid by 38%. Thyroid growth and 125 I uptake were also compared in intact and decentralized hemithyroids obtained from animals subjected to unilateral superior cervical ganglion decentralization. Unilateral superior cervical ganglion decentralization led to a reduction in thyroid weight, in 125 I uptake by thyroid tissue, and in TSH-induced stimulation of 125 I uptake in decentralized hemithyroids. These results suggest that sympathetic activity in thyroid contributes to gland enlargement and may modulate tissue responsiveness to TSH. cold exposure; diet; fasting; iodine deficiency; pregnancy THE THYROID GLAND IS RICHLY innervated by autonomic nerves. Although the potential importance of this innervation was recognized well over 100 years ago (17, 25), the precise roles played by the adrenergic, cholinergic, and peptidergic components of the thyroid innervation in the regulation of glandular function are unclear even today. Because nerve endings have been noted in proximity to thyroid follicles (37, 39), a neural role in thyroid regulation appears likely. In vitro studies have provided considerable information regarding tissue and cellular responses to diverse biogenic amines and neuropeptides (1), although the contributions of these agents in vivo are largely unknown. This lack of information arises, in part, from the following problem. Because the potential effects of thyroid nerves are inhibitory as well as stimulatory, changes in thyroid function after either disruption or excitation of efferent neural pathways cannot be attributed to specific neural events. Furthermore, the principal methods employed to assess the activity of thyroid nerves in any given setting have been based on functional differences observed between intact and denervated thyroid glands. Consequently, assignment of specific effects to thyroid nerves is largely inferential.To circumvent this problem, we used a technique independent of glandular function to study thyroid neural physiology. Techniques of norepinephrine (NE) turnover assess the dynamic behavior of neuronal NE stores and provide a generally accepted index of the functional state of the sympathetic nervous system (SNS) in innervated tissues of unanesthetized, unrest...

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Effects of thyroid hormones and cold exposure on turnover of norepinephrine in cardiac and skeletal muscle

Cited by 29 publications

References 0 publications

The Influence of Hormonal and Neuronal Factors on Rat Heart Adrenoceptors

The Influence of Hormonal and Neuronal Factors on Rat Heart Adrenoceptors

Effect of Diet and Cold Exposure on Norepinephrine Turnover in Brown Adipose Tissue of the Rat

Sympathetic nervous system activity in rat thyroid: potential role in goitrogenesis

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