Thyroxine: effect on behavioral thermoregulation in fishes

1982 ◽  
Vol 60 (5) ◽  
pp. 926-928 ◽  
Author(s):  
William W. Reynolds ◽  
Martha E. Casterlin ◽  
Richard E. Spieler
Keyword(s):  
Thyroid Hormones ◽  
Fish Species ◽  
Chronic Exposure ◽  
Acute Exposure ◽  
Behavioral Thermoregulation ◽  
Ambient Water ◽  
Thermoregulatory Behavior ◽  
Preferred Temperature ◽  
Preferred Temperatures

Exposure to thyroxine in the ambient water significantly lowered the preferred temperatures of two fish species. Acute exposure to thyroxine at a concentration of 20 μg/L of water lowered the preferred temperature by approximately 2 °C, while chronic exposure to the same concentration for 14 days prior to testing lowered the preferred temperature by as much as 10 °C. Chronic exposure for 14 days to thiourea (0.33 g/L), a thyroxine antagonist, raised the preferred temperature by 2.6 °C. These results suggest a role of thyroid hormones in thermoregulatory behavior of ectothermic vertebrates.

Behavioral thermoregulation and locomotor activity of Perca flavescens

1979 ◽  
Vol 57 (11) ◽  
pp. 2239-2242 ◽  
Author(s):  
William Wallace Reynolds ◽  
Martha Elizabeth Casterlin
Keyword(s):  
Locomotor Activity ◽  
Yellow Perch ◽  
Local Minimum ◽  
Perca Flavescens ◽  
Behavioral Thermoregulation ◽  
Major Peak ◽  
Nocturnal Activity ◽  
Preferred Temperature ◽  
Preferred Temperatures ◽  
The Relationship

Ten yearling yellow perch (Perca flavescens) were tested individually for 3-day periods in electronic shuttleboxes to determine their diel patterns of behavioral thermoregulation and of locomotor activity relative to a natural April photoperiod, and to determine the relationship between preferred temperatures and activity. The perch exhibited a diel rhythm of preferred temperature, with a predawn minimum of 16.7 °C and a dusk maximum of 23.8 °C. The 24-h mean was 20.2 °C; the diurnal mean was 21.5 °C and the nocturnal mean was 18.5 °C. Locomotor activity (quantified as mean photocell-monitored light-beam interruptions per hour) was crepuscular, with a major peak (25 units/h) at dusk, and a smaller peak (14.4 units/h) at dawn. Nocturnal activity was slightly greater (5.3 units/h) than diurnal activity (4.4 units/h). Locomotor activity relative to temperature exhibited a local minimum (0.4–6.2 units/h) at 22.2 °C.

The Role of Zinc in Thyroid Hormones Metabolism

2019 ◽  
Vol 89 (1-2) ◽  
pp. 80-88 ◽  
Author(s):  
Juliana Soares Severo ◽  
Jennifer Beatriz Silva Morais ◽  
Taynáh Emannuelle Coelho de Freitas ◽  
Ana Letícia Pereira Andrade ◽  
Mayara Monte Feitosa ◽  
...  
Keyword(s):  
Thyroid Hormones ◽  
Scientific Evidence ◽  
Thyroid Stimulating Hormone ◽  
Zinc Transporters ◽  
Serum Concentrations ◽  
Metabolic Adaptations ◽  
Serum T3 ◽  
Regulatory Effects ◽  
Shed Light

Abstract. Thyroid hormones play an important role in body homeostasis by facilitating metabolism of lipids and glucose, regulating metabolic adaptations, responding to changes in energy intake, and controlling thermogenesis. Proper metabolism and action of these hormones requires the participation of various nutrients. Among them is zinc, whose interaction with thyroid hormones is complex. It is known to regulate both the synthesis and mechanism of action of these hormones. In the present review, we aim to shed light on the regulatory effects of zinc on thyroid hormones. Scientific evidence shows that zinc plays a key role in the metabolism of thyroid hormones, specifically by regulating deiodinases enzymes activity, thyrotropin releasing hormone (TRH) and thyroid stimulating hormone (TSH) synthesis, as well as by modulating the structures of essential transcription factors involved in the synthesis of thyroid hormones. Serum concentrations of zinc also appear to influence the levels of serum T3, T4 and TSH. In addition, studies have shown that Zinc transporters (ZnTs) are present in the hypothalamus, pituitary and thyroid, but their functions remain unknown. Therefore, it is important to further investigate the roles of zinc in regulation of thyroid hormones metabolism, and their importance in the treatment of several diseases associated with thyroid gland dysfunction.

Glucose disposal and lipid metabolism in man: role of thyroid hormones

1988 ◽  
Vol 117 (4_Suppl) ◽  
pp. S130-S131
Author(s):  
M. J. MÜLLER ◽  
A. G. BURGER ◽  
E. JEQUIER ◽  
K.J. ACHESON
Keyword(s):  
Lipid Metabolism ◽  
Thyroid Hormones ◽  
Glucose Disposal

scholarly journals Role of Thyroid Hormones in Skeletal Development and Bone Maintenance

2016 ◽  
Vol 37 (2) ◽  
pp. 135-187 ◽  
Author(s):  
J. H. Duncan Bassett ◽  
Graham R. Williams
Keyword(s):  
Thyroid Hormones ◽  
Skeletal Development ◽  
Bone Maintenance

scholarly journals Vulnerability to climate change of a microendemic lizard species from the central Andes

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
A. Laspiur ◽  
J. C. Santos ◽  
S. M. Medina ◽  
J. E. Pizarro ◽  
E. A. Sanabria ◽  
...  
Keyword(s):  
Climate Change ◽  
Species Distribution Models ◽  
Activity Patterns ◽  
Geographic Range ◽  
Behavioral Thermoregulation ◽  
Rapid Loss ◽  
Distribution Models ◽  
Lizard Species ◽  
Vulnerability To Climate Change

AbstractGiven the rapid loss of biodiversity as consequence of climate change, greater knowledge of ecophysiological and natural history traits are crucial to determine which environmental factors induce stress and drive the decline of threatened species. Liolaemus montanezi (Liolaemidae), a xeric-adapted lizard occurring only in a small geographic range in west-central Argentina, constitutes an excellent model for studies on the threats of climate change on such microendemic species. We describe field data on activity patterns, use of microhabitat, behavioral thermoregulation, and physiology to produce species distribution models (SDMs) based on climate and ecophysiological data. Liolaemus montanezi inhabits a thermally harsh environment which remarkably impacts their activity and thermoregulation. The species shows a daily bimodal pattern of activity and mostly occupies shaded microenvironments. Although the individuals thermoregulate at body temperatures below their thermal preference they avoid high-temperature microenvironments probably to avoid overheating. The population currently persists because of the important role of the habitat physiognomy and not because of niche tracking, seemingly prevented by major rivers that form boundaries of their geographic range. We found evidence of habitat opportunities in the current range and adjacent areas that will likely remain suitable to the year 2070, reinforcing the relevance of the river floodplain for the species’ avoidance of extinction.

Association of Dyskalemias with Ischemic Stroke in Advanced Chronic Kidney Disease Patients Transitioning to Dialysis

2021 ◽  
pp. 1-9
Author(s):  
Ankur A. Dashputre ◽  
Keiichi Sumida ◽  
Fridtjof Thomas ◽  
Justin Gatwood ◽  
Oguz Akbilgic ◽  
...  
Keyword(s):  
Chronic Kidney Disease ◽  
Ischemic Stroke ◽  
Kidney Disease ◽  
Lower Risk ◽  
Chronic Exposure ◽  
Cox Regression ◽  
Acute Exposure ◽  
Continuous Exposure ◽  
Advanced Chronic Kidney Disease

<b><i>Introduction:</i></b> Hypo- and hyperkalemia are associated with a higher risk of ischemic stroke. However, this association has not been examined in an advanced chronic kidney disease (CKD) population. <b><i>Methods:</i></b> From among 102,477 US veterans transitioning to dialysis between 2007 and 2015, 21,357 patients with 2 pre-dialysis outpatient estimated glomerular filtration rates &#x3c;30 mL/min/1.73 m<sup>2</sup> 90–365 days apart and at least 1 potassium (K) each in the baseline and follow-up period were identified. We separately examined the association of both baseline time-averaged K (chronic exposure) and time-updated K (acute exposure) treated as categorized (hypokalemia [K &#x3c;3.5 mEq/L] and hyperkalemia [K &#x3e;5.5 mEq/L] vs. referent [3.5–5.5 mEq/L]) and continuous exposure with time to the first ischemic stroke event prior to dialysis initiation using multivariable-adjusted Cox regression models. <b><i>Results:</i></b> A total of 2,638 (12.4%) ischemic stroke events (crude event rate 41.9 per 1,000 patient years; 95% confidence interval [CI] 40.4–43.6) over a median (Q<sub>1</sub>–Q<sub>3</sub>) follow-up time of 2.56 (1.59–3.89) years were observed. The baseline time-averaged K category of hypokalemia (adjusted hazard ratio [aHR], 95% CI: 1.35, 1.01–1.81) was marginally associated with a significantly higher risk of ischemic stroke. However, time-updated hyperkalemia was associated with a significantly lower risk of ischemic stroke (aHR, 95% CI: 0.82, 0.68–0.98). The exposure-outcome relationship remained consistent when using continuous K levels for both the exposures. <b><i>Discussion/Conclusion:</i></b> In patients with advanced CKD, hypokalemia (chronic exposure) was associated with a higher risk of ischemic stroke, whereas hyperkalemia (acute exposure) was associated with a lower risk of ischemic stroke. Further studies in this population are needed to explore the mechanisms underlying these associations.

scholarly journals Vasoactive Effects of Acute Ergot Exposure in Sheep

Toxins ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 291
Author(s):  
Rossalin Yonpiam ◽  
Jair Gobbet ◽  
Ashok Jadhav ◽  
Kaushik Desai ◽  
Barry Blakley ◽  
...  
Keyword(s):  
Single Dose ◽  
Chronic Exposure ◽  
Contractile Response ◽  
Ergot Alkaloids ◽  
Acute Exposure ◽  
Control Group ◽  
Vascular Effects ◽  
Adrenergic Antagonist ◽  
Vascular Sensitivity ◽  
Dose Dependent

Ergotism is a common and increasing problem in Saskatchewan’s livestock. Chronic exposure to low concentrations of ergot alkaloids is known to cause severe arterial vasoconstriction and gangrene through the activation of adrenergic and serotonergic receptors on vascular smooth muscles. The acute vascular effects of a single oral dose with high-level exposure to ergot alkaloids remain unknown and are examined in this study. This study had two main objectives; the first was to evaluate the role of α1-adrenergic receptors in mediating the acute vasocontractile response after single-dose exposure in sheep. The second was to examine whether terazosin (TE) could abolish the vascular contractile effects of ergot alkaloids. Twelve adult female sheep were randomly placed into control and exposure groups (n = 6/group). Ergot sclerotia were collected and finely ground. The concentrations of six ergot alkaloids (ergocornine, ergocristine, ergocryptine, ergometrine, ergosine, and ergotamine) were determined using HPLC/MS at Prairie Diagnostic Services Inc., (Saskatoon, SK, Canada). Each ewe within the treatment group received a single oral treatment of ground ergot sclerotia at a dose of 600 µg/kg BW (total ergot) while each ewe in the control group received water. Animals were euthanized 12 h after the treatment, and the pedal artery (dorsal metatarsal III artery) from the left hind limb from each animal was carefully dissected and mounted in an isolated tissue bath. The vascular contractile response to phenylephrine (PE) (α1-adrenergic agonist) was compared between the two groups before and after TE (α1-adrenergic antagonist) treatment. Acute exposure to ergot alkaloids resulted in a 38% increase in vascular sensitivity to PE compared to control (Ctl EC50 = 1.74 × 10−6 M; Exp EC50 = 1.079 × 10−6 M, p = 0.046). TE treatment resulted in a significant dose-dependent increase in EC50 in both exposure and control groups (p < 0.05 for all treatments). Surprisingly, TE effect was significantly more pronounced in the ergot exposed group compared to the control group at two of the three concentrations of TE (TE 30 nM, p = 0.36; TE 100 nM, p < 0.001; TE 300 nM, p < 0.001). Similar to chronic exposure, acute exposure to ergot alkaloids results in increased vascular sensitivity to PE. TE is a more potent dose-dependent antagonist for the PE contractile response in sheep exposed to ergot compared to the control group. This study may indicate that the dry gangrene seen in sheep, and likely other species, might be related to the activation of α1-adrenergic receptor. This effect may be reversed using TE, especially at early stages of the disease before cell death occurs. This study may also indicate that acute-single dose exposure scenario may be useful in the study of vascular effects of ergot alkaloids.

scholarly journals Inhibition of hepatic deiodination of thyroxine is caused by selenium deficiency in rats

1987 ◽  
Vol 248 (2) ◽  
pp. 443-447 ◽  
Author(s):  
G J Beckett ◽  
S E Beddows ◽  
P C Morrice ◽  
F Nicol ◽  
J R Arthur
Keyword(s):  
Thyroid Hormones ◽  
Production Rate ◽  
Selenium Deficiency ◽  
Enzyme Complex ◽  
Measurable Effect ◽  
Direct Role ◽  
Mechanism Of Inhibition ◽  
Se Deficiency

Selenium (Se) deficiency produced up to a 14-fold decrease in hepatic tri-iodothyronine (T3) production from thyroxine (T4) in vitro. The T3 production rate could not be restored by the addition of a variety of cofactors, nor by the addition of control homogenate. The impairment in hepatic T3 production observed in Se deficiency was reflected in the concentrations of thyroid hormones circulating in plasma, T4 being increased approx. 40% and T3 being decreased by 30%. However, the fall in plasma T3 concentrations was smaller than might be expected in view of the marked decreased in T3 production. Se deficiency had no measurable effect on plasma reverse-tri-iodothyronine concentrations. The data suggest that Se deficiency produces an inhibition of both 5- and 5′-deiodination, consistent with the widely held view that these reactions are catalysed by the same enzyme complex. The mechanism of inhibition appears not be mediated by changes in thiol levels, but a direct role of Se in the activity of the deiodinase complex cannot be excluded.

Immunomodulatory role of thyroid hormones: in vivo effect of thyroid hormones on the blastogenic response of lymphoid tissues

1983 ◽  
Vol 103 (1) ◽  
pp. 95-100 ◽  
Author(s):  
Sadhana Chatterjee ◽  
Amar Singh Chandel
Keyword(s):  
Thyroid Hormones ◽  
Pokeweed Mitogen ◽  
Lymphoid Tissues ◽  
Mesenteric Lymph Nodes ◽  
Mesenteric Lymph ◽  
Hormone Administration ◽  
Blastogenic Response ◽  
Significant Depression

Abstract. In an attempt to find out the mechanism of immunomodulation by thyroid hormones (T3 and T4), their in vivo effect on the blastogenic response of lymphocytes from various lymphoid tissues of hormonetreated and thyroidectomized rats were studied. The blastogenic response of lymphocytes from thymus, peripheral blood and mesenteric lymph nodes to pokeweed mitogen (PWM) was found to be increased significantly following T3 or T4 administration for 15 days or 30 days. However, the response to phytohaemagglutinin (PHA) increased only after 1 month of T3 or T4 administration. The blastogenic response of spleen cells to both PHA and PWM was, on the other hand, found to be depressed following 15 days of hormone administration. Thyroidectomy invariably induced significant depression in the blastogenic response to both PHA and PWM in lymphocytes of all the lymphoid tissues. Thyroid hormone (T3) administration was found to restore the blastogenic response of the lymphocytes of thyroidectomized animals.

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