Iodide and thyroxine metabolism in the brook trout, Salvelinus fontinalis (Mitchill), during sustained exercise

1971 ◽  
Vol 49 (9) ◽  
pp. 1255-1269 ◽  
Author(s):  
D. A. Higgs ◽  
J. G. Eales
Keyword(s):  
Thyroid Hormone ◽  
Brook Trout ◽  
Salvelinus Fontinalis ◽  
Specific Activity ◽  
Hormone Secretion ◽  
Conversion Ratio ◽  
Limited Extent ◽  
Thyroid Activity ◽  
Individual Variations ◽  
Serum Ratio

Iodide and thyroxine metabolism were followed in exercised and non-exercised starved trout.Radioiodide (125I) parameters suggested a slight increase in thyroid activity (% dose in thyroid, thyroid/serum ratio (T/S), and conversion ratio (CR)) and an increase in extrathyroidal 125I excretion resulting from exercise.The generally high and variable serum 127I levels increased up to 496 μg% during the experiments, being consistently higher in exercised fish. Individual variations in serum 127I were related in many instances to radioiodide parameters (I125I, T/S, CR) and to a limited extent to % thyroid. This demonstrates the uncertainty of radioiodide measurements when the specific activity of circulating 125I changes and the need for assessing 127I levels in radioiodide studies.Tissue uptake of radioactivity and serum loss of protein-bound radioactivity following radiothyroxine intraperitoneal injection, as well as serum stable thyronine levels, suggested both increased biliary loss of thyroid hormones and a higher thyroid hormone secretion rate as the result of exercise.

The influence of temperature on histological and radiochemical measurements of thyroid activity in the eastern brook trout, Salvelinus fontinalis Mitchell

1968 ◽  
Vol 46 (1) ◽  
pp. 1-9 ◽  
Author(s):  
D. E. Drury ◽  
J. G. Eales
Keyword(s):  
Epithelial Cell ◽  
Brook Trout ◽  
Salvelinus Fontinalis ◽  
Acclimation Temperature ◽  
Thyroid Follicle ◽  
Thyroid Activity ◽  
Cell Height ◽  
Different Temperatures ◽  
Influence Of Temperature On ◽  
T Values

Histological and radiochemical techniques for assessing thyroid activity were compared on yearling brook trout acclimated at 5, 12, and 15 °C.The mean thyroid follicle epithelial cell height was 7.4 μ (range 6.0–8.6 μ) at 5 °C; 3.5 μ (range 2.9–3.9 μ) at 12 °C, and 2.3 μ (range 1.9–2.9 μ) at 15 °C. Assuming that a taller epithelial cell height indicates greater thyroid activity, then an inverse relationship between thyroid activity and acclimation temperature exists.Both the uptake of radioiodide by the thyroid (T/S) and the clearance of radioiodide from the serum were greater at higher temperatures. Serum PB125I production was negligible within 8 days after radioiodide injection and the conversion ratio could not be applied as an index of thyroid function, Assuming, however, that the thyroid radioiodide uptake is an index of thyroid activity, then there is a direct relationship between thyroid activity and acclimation temperature.In view of the marked discrepancy between these histological and radiochemical techniques, fractional rates of turnover of serum thyroxine were compared by determining the biological half-life (t½) for serum PB125I after L-thyroxine-125I intraperitoneal injection at different temperatures. The serum PB125I clearance curves were complex and tentative t½ values of 18.0 days (5 °C, 3.2 days (12 °C), and 1.5 days (15 °C) were obtained. These results indicate a more rapid serum PBI turnover at higher temperatures and support the radiochemical measurements.

Thyroid function as measured by 131iodine release rate, weight and RNA/DNA in growing lambs, and its relation to growth rate

1969 ◽  
Vol 11 (3) ◽  
pp. 399-407 ◽  
Author(s):  
S. A. Draper ◽  
N. B. Haynes ◽  
I. R. Falconer ◽  
G. E. Lamming
Keyword(s):  
Growth Rate ◽  
Thyroid Hormone ◽  
Thyroid Gland ◽  
Thyroid Function ◽  
Rate Constant ◽  
Release Rate ◽  
Hormone Secretion ◽  
Thyroid Status ◽  
Thyroid Activity ◽  
Ad Libitum

SUMMARYThyroid activity was assessed in two groups of crossbred lambs and in Dorset Horn lambs fed ad libitum, by measuring the rate constant (K4) for the release of 131iodine from the gland. The results demonstrated a highly significant curvilinear correlation (P<0·001) between growth rate and the rate constant (K4) in experiments based on individual measurements in animals from three populations.Separate work carried out on the measurements of both thyroid size and RNA/DNA ratio suggests a need for caution when these are interpreted as parameters of thyroid activity. In the growing animal these may be more reflective of the growth of the thyroid gland itself, differences which may be governed by factors not directly related to variations in hormone secretion rate.The findings are discussed in terms of an explanation of the contradictory results obtained where attempts have been made to alter the thyroid status of growing animals by the use of thyroid hormone analogues and thyroid depressant drugs.

CHANGES IN THYROID ACTIVITY DURING GROWTH IN THE SHEEP

1961 ◽  
Vol 22 (1) ◽  
pp. 23-30 ◽  
Author(s):  
I. R. FALCONER ◽  
H. A. ROBERTSON
Keyword(s):  
Body Weight ◽  
Energy Metabolism ◽  
Thyroid Hormone ◽  
Rate Constants ◽  
Hormone Secretion ◽  
Secretion Rate ◽  
Initial Increase ◽  
Thyroid Activity ◽  
Thyroid Uptake ◽  
Unit Body Weight

SUMMARY The rate constants for thyroid uptake (K1) and release (K4) of 131I, the serum protein-bound iodine (PBI) level and the rate of secretion of thyroid hormone have been determined for sheep from 5 weeks to 7 years old. The secretion rate of thyroid hormone has been shown to increase rapidly up to the age of 6–8 months, and then decline slightly with increasing age. The rate constant for 131I release from the thyroid (K4), showed an increase up to 1 year of age, and considerably lower values at 5 and 7 years old. When the thyroid hormone secretion rate is expressed per unit body weight, the highest rate was observed at approx. 6 months of age or 20–40 kg. body weight. The significance of this initial increase in thyroid hormone secretion rate per unit body weight is discussed in conjunction with the results of other workers on the energy metabolism of immature animals. Serum PBI levels decreased sharply during the 1st year of life and then remained relatively constant.

Growth Inhibition, Gluconeogenesis, and Morphometric Studies of the Pituitary and Interrenal Cells of Acid-Stressed Brook Trout (Salvelinus fontinalis)

1988 ◽  
Vol 45 (7) ◽  
pp. 1197-1211 ◽  
Author(s):  
W. H. Tam ◽  
J. N. Fryer ◽  
I. Ali ◽  
M. R. Dallaire ◽  
B. Valentine
Keyword(s):  
Brook Trout ◽  
Salvelinus Fontinalis ◽  
Hormone Secretion ◽  
Acid Stress ◽  
Somatic Growth ◽  
Experimental Period ◽  
Plasma Cortisol Level ◽  
Electron Microscopic ◽  
Cell Hyperplasia ◽  
Plasma Protein Concentration

Somatic growth was stunted in yearling brook trout (Salvelinus fontinalis) maintained for up to 73 d in pH 4.5. Plasma cortisol level increased in pulses after 1.5 h (from 10 to 82.3 ng∙mL−1) on days 4 (46 ng∙mL−1) and 15–30 (20–25 ng∙mL−1) of acid treatment. Interrenal nuclear hypertrophy and cell hyperplasia occurred respectively on days 4 and 15. Electron microscopic observations revealed that the somatotropes and thyrotropes were atrophic for about half of the experimental period whereas the corticotropes displayed sustained hypertrophy. Plasma glucose and amino acid levels rose simultaneously by 300–600 and 130%, respectively, from day 4 of acid exposure. Hepatic L-alanine aminotransferase activity increased on day 30 just as plasma protein concentration began to decline. When adrenalin and cortisol acetate were administered to trout maintained in neutral pH to raise circulating cortisol levels from 10–20 to 1876 ng∙mL−1, blood glucose remained normal up to 6 d after treatment. These results suggested that acid stress suppressed somatotropin, thyrotropin, and indirectly thyroid hormone secretion but stimulated the pituitary–interrenal axis, leading to inhibition of protein synthesis and accumulation of amino acids in the circulation. The elevation of blood sugar level was caused by some as yet unidentified factors.

ACTION OF POTASSIUM IODIDE ON THYROID ACID PROTEASE

1973 ◽  
Vol 74 (4) ◽  
pp. 703-710 ◽  
Author(s):  
M. A. Pisarev ◽  
N. Altschuler
Keyword(s):  
Thyroid Hormone ◽  
Potassium Iodide ◽  
Enzyme Preparation ◽  
Specific Activity ◽  
Hormone Secretion ◽  
Enzyme Synthesis ◽  
Acid Protease ◽  
Rule Out ◽  
Stimulation Of

ABSTRACT Potassium iodide (KI) is known to inhibit thyroid hormone secretion. In the present studies its action on the proteolytic step of this process was investigated. Rats were treated with KI (200 μg/ml in the drinking water) for 30 days. This treatment caused a decrease of protease activity in total homogenate and in the specific activity of a 15 000 × g pellet. No alteration in the pattern of subcellular distribution was observed. In order to rule out an action of KI on enzyme activity its in vitro action was studied. KI concentrations around 103-–10−4 m were without effect, though 10−2 caused a stimulation of activity. Similar results were observed when a liver enzyme preparation was checked under the same conditions. Neither CL− nor F− had an effect on thyroid or liver protease at concentrations between 10−2 to 10−4 m. The present results suggest that KI inhibition of thyroid hormone secretion can be explained at least in part by its action on acid protease. Moreover, the lack of an in vitro inhibitory affect of KI would suggests that this drug affects enzyme synthesis and/or breakdown.

Influence of acclimation temperature on rate constants for thyroid uptake of iodide by brook trout, Salvelinus fontinalis (Mitchill)

1971 ◽  
Vol 49 (5) ◽  
pp. 783-786 ◽  
Author(s):  
Carolyn D. Smith ◽  
J. G. Eales
Keyword(s):  
Rate Constant ◽  
Rate Constants ◽  
Brook Trout ◽  
Salvelinus Fontinalis ◽  
Acclimation Temperature ◽  
Thyroid Activity ◽  
Iodide Uptake ◽  
Individual Fish ◽  
Thyroid Uptake

A procedure for determining the rate constant for thyroid iodide uptake for fish is described.Rate constants for thyroid iodide uptake in brook trout agreed with previously used indices of thyroid activity (T/S and CR) in indicating a more active thyroid at 16C than 10C.At both temperatures radioiodide metabolism was extremely slow with considerable variation between individual fish. These features may be attributed to the high and variable serum stable iodide level in this species.

INHIBITION BY SOMATOSTATIN OF MOUSE THYROID ACTIVITY FOLLOWING STIMULATION BY THYROTROPHIN, ISOPRENALINE AND DIBUTYRYL CYCLIC-AMP

1977 ◽  
Vol 86 (2) ◽  
pp. 323-329 ◽  
Author(s):  
B. Ahrén ◽  
P. Hedner ◽  
A. Melander ◽  
U. Westgren
Keyword(s):  
Thyroid Hormone ◽  
Thyroid Gland ◽  
Cyclic Amp ◽  
Hormone Secretion ◽  
Inhibitory Effect ◽  
Dibutyryl Cyclic Amp ◽  
Thyroid Activity ◽  
Iodine Release ◽  
Mouse Thyroid

ABSTRACT The recent discovery of somatostatin-containing cells within the thyroid gland infers that somatostatin may influence thyroid activity. This possibility was investigated by measurements of radio-iodine release in mice pre-treated with 125I and T4. The animals were treated with TSH, isoprenaline or dibutyryl-cyclic AMP with and without concomitant injection of somatostatin. It was found that somatostatin reduced the blood 125I increase in response to each of the three thyroid-stimulating agents. The elimination rates of 125I-labelled T4 and T3 were unaffected by somatostatin. The observations suggests that somatostatin may participate in the regulation of thyroid hormone secretion, by an inhibitory effect exerted within the thyroid gland.

STUDIES ON THYROIDAL COLLOID PINOCYTOSIS USING A DOUBLE ISOTOPE TECHNIQUE

1972 ◽  
Vol 70 (1) ◽  
pp. 48-55 ◽  
Author(s):  
Mario A. Pisarev ◽  
Noe Altschuler ◽  
Leslie J. DeGroot
Keyword(s):  
Acid Phosphatase ◽  
Thyroid Hormone ◽  
Trichloroacetic Acid ◽  
Specific Activity ◽  
Acid Precipitation ◽  
Solvent System ◽  
Blood Stream ◽  
Radioactive Materials ◽  
Isotope Technique ◽  
Double Isotope

ABSTRACT The process of secretion of the thyroid hormone involves several steps: pinocytosis of thyroglobulin, fusion of the colloid droplets with the lysosomes, digestion of thyroglobulin by a cathepsin, dehalogenation of tyrosines and release of thyronines into the blood stream. The present paper describes a double isotope technique for studying the first two steps. Thyrotrophin (TSH) administration to rats increased the radioactivity present in all fractions, specially in the 15 000 × g pellet. When the subcellular distribution of acid phosphatase was determined, the highest specific activity was found in this fraction, thus indicating the presence of lysosomes. The content of radioactive materials in the 15 000 × g pellet was analyzed by trichloroacetic acid precipitation and by ascending paper chromatography using n-butanol:ethanol:ammonium hydroxide (5:1:2;v/v) as solvent system. The results obtained showed that 90% of the radioactivity was protein bound and strongly suggest that this material is thyroglobulin.

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