scholarly journals Comparative Studies of the Thyroid Function in Teleosts of Tropical and Temperate Habitats

1955 ◽  
Vol 32 (3) ◽  
pp. 504-513
Author(s):  
P. Y. FORTUNE
Keyword(s):  
Seasonal Variation ◽  
Thyroid Function ◽  
Comparative Studies ◽  
Thyroid Activity ◽  
Thermal Range ◽  
Environmental Temperatures ◽  
Thiourea Treatment

1. Normal and thiourea-treated Phoxinus and Lebistes show a depression of thyroid activity by low environmental temperatures and stimulation by high. 2. Thiourea treatment affects the thermal range in both species. 3. Phoxinus shows a seasonal variation in thyroid activity, correlated with breeding periods. This is absent in Lebistes. 4. No effect of the thyroid on growth could be demonstrated.

EFFECTS OF HYPOTHALAMIC LESIONS AND OF COLD ON THYROID ACTIVITY IN THE RAT

1961 ◽  
Vol 38 (4) ◽  
pp. 585-597 ◽  
Author(s):  
L. van Beugen ◽  
J. J. van der Werff ten Bosch
Keyword(s):  
Thyroid Function ◽  
Half Life ◽  
Anterior Part ◽  
Hypothalamic Lesion ◽  
Thyroid Activity ◽  
Hypothalamic Lesions ◽  
Biological Half Life ◽  
Exposed Animal ◽  
Environmental Temperatures ◽  
Made In

ABSTRACT The effect was studied of an electrolytic basal midline lesion in the anterior part of the hypothalamus on thyroid activity of rats exposed to environmental temperatures of 24° C and 4° C. The index of thyroid function used was the biological half-life of thyroidal 131I calculated from the amount of radioactivity released by the gland in seven days. In one experiment, thyroid function was studied at 24° C one month after the placement of a lesion and at 4° C a month later. In another experiment hypothalamic lesions were made in the middle of a release study, during which some of the animals were kept at 24° C and others at 4° C. The two experiments yielded comparable results; the biological half-life values were approximately 7½ days at 24° C and 4 days at 4° C in intact or blank-operated rats, and approximately 13 days at 24° C and 7 days at 4° C in rats with a hypothalamic lesion. Thyroid 127I contents of various groups were identical. It appears that the biological half-life was reduced to approximately half the normal value by exposure to cold, that a lesion caused doubling of the half-life and that summation of the two effects was produced, when a lesioned rat was exposed to cold or when a cold-exposed animal was lesioned. The basal midline region of the hypothalamus destroyed by the lesions, whilst appearing to be essential for the maintenance of »spontaneous« thyroid activity, does not seem to be essential for the thyroid response to cold. Observations on so-called goitre-block lesions are discussed in the light of these findings.

scholarly journals Seasonal variation in sleeping metabolic rate, thyroid activity, and leptin

2003 ◽  
Vol 285 (2) ◽  
pp. E338-E343 ◽  
Author(s):  
Guy Plasqui ◽  
Arnold D. M. Kester ◽  
Klaas R. Westerterp
Keyword(s):  
Body Composition ◽  
Seasonal Variation ◽  
Metabolic Rate ◽  
Compartment Model ◽  
Fat Free Mass ◽  
Interindividual Variation ◽  
Dilution Method ◽  
Thyroid Activity ◽  
Intraindividual Variation ◽  
Total Thyroxine

We investigated seasonal variation in sleeping metabolic rate (SMR) and the possible relation to body composition, thyroid activity, and leptin. Twenty-five healthy volunteers were examined four times during the year: in spring (April, May), summer (July, August), autumn (October, November), and winter (January, February). Body composition was determined using a three-compartment model based on underwater weighing and the deuterium dilution method. SMR was measured during an overnight stay in a respiration chamber. A blood sample was taken for the analysis of free and total thyroxine, TSH, and leptin. SMR showed a significant seasonal variation ( P < 0.01) with a maximum in winter (4.54 kJ/min) and a minimum in summer (4.34 kJ/min). The amplitude was 0.10 ± 0.02 kJ/min, and the phase was November 5th. Season explained 17% of the intraindividual variation in SMR. The circannual rhythm in SMR could not be explained by changes in body composition, thyroid activity, or leptin. Interindividual variation in SMR was explained by fat-free mass ( P < 0.001) and leptin ( P < 0.001).

scholarly journals Seasonal variation in thyroid activity of turtle Lissemys punctata with respect to annual cycle of reproduction

2010 ◽  
Vol 2 (2) ◽  
pp. 194-199
Author(s):  
Vidya R. Chandavar ◽  
Prakash R. Naik
Keyword(s):  
Seasonal Variation ◽  
Reproductive Cycle ◽  
Annual Cycle ◽  
Seasonal Cycle ◽  
Maximum Size ◽  
Reproductive Period ◽  
Thyroid Activity ◽  
The Relationship

The objective of the present investigation was to study the relationship between thyroid activity and reproductive cycle in turtle Lissemys punctata. The animals were studied in the annual seasonal cycle of reproduction for two consecutive years, which is distinguished into three separate periods namely regenerative, reproductive and recrudescent. The thyroid in L. punctata was observed to be a single pyramid shaped gland, creamy white to reddish-brown in color with lenticular profile. The diameter of the follicle was lowest in regenerative period, whichgradually increased in reproductive period attaining maximum size in recrudescent, where as epithelial height was highest in regenerative period, which gradually decreased in reproductive period reaching minimum in recrudescent period. Thyroid activity varies annually in relation to different phases of reproductive periods.

Comparative indexes of thyroid function in sheep

1961 ◽  
Vol 201 (5) ◽  
pp. 819-822 ◽  
Author(s):  
T. M. Hoersch ◽  
H. E. Henderson ◽  
E. P. Reineke ◽  
H. A. Henneman
Keyword(s):  
Thyroid Function ◽  
Hormone Secretion ◽  
Secretion Rate ◽  
Half Time ◽  
Thyroid Activity ◽  
Height Measurement ◽  
Cell Height ◽  
Thyroid Epithelial Cell ◽  
Thyroid Secretion ◽  
Zero Time

The effects of light and temperature on thyroid activity of sheep were assessed by four methods: thyroid secretion rate, zero time per cent uptake of I131, I131 output half-time, and measurement of the thyroid epithelial cell height. Increased ambient temperature inhibited thyroid activity as evaluated by all methods. Reduced temperatures consistently resulted in a depressed uptake of I131. I131 output half-time had no relationship with actual hormone secretion. Light alterations imposed the same trend on thyroid function when activity was assessed by secretion rate and cell height measurement. As evaluated by these two methods the lowest thyroid activity was observed at 12 hr of illumination per day and increased with both increasing and decreasing light beyond this 1:1 light-to-dark ratio. When the three isotopic measures of thyroid activity were correlated with the histological method the highest correlation was found between cell height and thyroid secretion.

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