Estimation of thyroxine secretion rate in reindeer, Rangifer tarandus: effects of sex, age and season (original) (raw)
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Journal of Animal Behaviour and Biometeorology, 2023
It is well known that the concentration of the thyroid hormone thyroxine increases as day length increases, and the other way around, in Karagouniko and Chios ewes but based on openly international English literature, nothing is known about this hormone on the rams of the breeds mentioned above concerning a meticulous analysis of their aerial environment. So from this perspective, the current research was conducted to investigate the thyroxine concentrations of Karagouniko and Chios rams, taking into account two periods, January-June and July-November, when the day length was increasing and decreasing, respectively. Apart from photoperiod, the meteorological variables air temperature, relative humidity, and sunshine were taken into consideration in the farm of the Artificial Insemination Center of Karditsa (39021΄18΄΄N, 21054΄19΄΄E), Greece (temperate climate zone), where the experimental animals raised. The possible change of thyroxine concentration in both sheep breeds and the possible changes of the abovementioned meteorological variables between the examined periods were detected using t-tests. Higher thyroxine values (P < 0.05) were confirmed in January-June (55.11 ng/ml in Karagouniko and 47.72 ng/ml in Chios rams), in comparison to July-November (49.03 ng/ml in Karagouniko and 44.14 ng/ml in Chios rams). Air temperature and sunshine followed a reverse course (P < 0.05). In both periods, Karagouniko rams were characterized by higher concentrations of thyroxine than Chios rams (P < 0.01). Our results add more insight into the physiology of Karagouniko and Chios sheep related to thyroxine and temperate aerial environment.
Journal of Comparative Physiology B-biochemical Systemic and Environmental Physiology, 1983
Changes in plasma total thyroxine, triiodothyronine (T3) and metabolic rate were investigated in both hydrated and dehydrated dik-diks after prolonged exposure to ambient temperatures (T a) of 25°C, 35°C and 15°C. AtT a of 25°C, metabolic rate, T3 and T4 were 2.58 W·kg−1, 56.3 ng ml−1 and 0.93 ng ml−1 for the hydrated group, and 1.95 W·kg−1, 70.0 ng ml−1 and 0.85 ng ml−1 for the dehydrated group, respectively. Exposure to 15°C increased metabolic rate and total hormonal concentrations in both groups. Following dehydration and exposure toT a of 35°C a significant decrease in metabolic rate occurred in the presence of a significant increase in both T3 and T4 concentrations. Levels of total plasma T3 and T4 alone are unlikely to be responsible for the decrease in metabolic rate observed in the dehydrated dik-dik antelopes.
General and Comparative Endocrinology, 1975
Leopard frogs (Rana pipiens complex) were given daily injections of Na-I-thyroxine (2.0 &lo g body wt) in the dorsal lymph sac, while control animals were given daily injections of equivalent volumes of the alkaline vehicle. Half of the animals were acclimated in darkness at a constant temperature of W, whereas the remaining frogs were acclimated in darkness at 25". At the end of 5.5 days of treatment, the frogs were sacrificed; and oxygen consumption of liver tissue from each animal was measured by differential respirometry at the temperature to which the donor was acclimated. Oxygen consumption of liver tissue from hyperthyroid frogs acclimated at 25" was 21% higher than it was in preparations from control animals acclimated at the same temperature. However, oxygen uptake by liver preparations from hyperthyroid frogs acclimated at 15" did not differ significantly from control levels. Thus, in anuran amphibians-as in reptilian ectotherms-temperature seems to govern the metabolic response of tissues to thyroid hormones.
CHANGES OF THYROID HORMONES IN DIFFERENT PHYSIOLOGICAL PERIODS IN WHITE GOATS
Journal of Animal and Plant Sciences
The levels of thyroid hormones are important indicator of metabolic activity. The knowledge of the metabolic activity in different physiological periods, animals readjusted dietary regimen. Therefore, in this study, changes of triiodotironine (T3) and thyroxine (T4) hormones in the blood serum of female (n=14) and male (n=9) white goats were studied for a duration of one year through different physiological periods [breeding (September-October), gestation (November to March), postpartum-sucking (April-May) and milking (June to August)]. Results show that the differences in T3 and T4 hormone levels between sexes are statistically unimportant in breeding, gestation, postpartum-sucking and milking periods, while the changes for each sex between the physiological periods are important (p<0.05). Also, it has been found out that the thyroid hormone levels in different physiological periods are under the influence of the environmental temperature changes.
PLoS ONE, 2014
Ansell's mole-rats (Fukomys anselli) are subterranean, long-lived rodents, which live in eusocial families, where the maximum lifespan of breeders is twice as long as that of non-breeders. Their metabolic rate is significantly lower than expected based on allometry, and their retinae show a high density of S-cone opsins. Both features may indicate naturally low thyroid hormone levels. In the present study, we sequenced several major components of the thyroid hormone pathways and analyzed free and total thyroxine and triiodothyronine in serum samples of breeding and non-breeding F. anselli to examine whether a) their thyroid hormone system shows any peculiarities on the genetic level, b) these animals have lower hormone levels compared to euthyroid rodents (rats and guinea pigs), and c) reproductive status, lifespan and free hormone levels are correlated. Genetic analyses confirmed that Ansell's mole-rats have a conserved thyroid hormone system as known from other mammalian species. Interspecific comparisons revealed that free thyroxine levels of F. anselli were about ten times lower than of guinea pigs and rats, whereas the free triiodothyronine levels, the main biologically active form, did not differ significantly amongst species. The resulting fT4:fT3 ratio is unusual for a mammal and potentially represents a case of natural hypothyroxinemia. Comparisons with total thyroxine levels suggest that mole-rats seem to possess two distinct mechanisms that work hand in hand to downregulate fT4 levels reliably. We could not find any correlation between free hormone levels and reproductive status, gender or weight. Free thyroxine may slightly increase with age, based on subsignificant evidence. Hence, thyroid hormones do not seem to explain the different ageing rates of breeders and nonbreeders. Further research is required to investigate the regulatory mechanisms responsible for the unusual proportion of free thyroxine and free triiodothyronine.
Dynamics of Thyroid Hormones in Growth and Development of South Indian Sheep (Bannur
Research Article , 2018
From the data bank of livestock census in India, the total sheep in the country is 65 million numbers in 2012, declined by about 9.09% over census 2007. The total sheep contributes around 12.7% of the total livestock population. Karnataka (South Indian province) contributes second highest in sheep population first is Andra Pradesh. Growth and development are continuous and dynamic processes require integration of numerous physiological functions, they influenced by nutrition, efficiency of metabolism, respiration, hormonal regulation, immune responses, physiological status, and maintenance of homeostasis. The physiological and endocrinological events involved in the onset of puberty and estrus cycle are of primary importance. Appropriate thyroid glands function and activity of thyroid hormones (TH) are considered crucial to sustain the productive performance in domestic animals (growth, milk, hair fiber production) and circulating TH can be considered as indicators of the metabolic and nutritional status of the animals. A total of 24 female Bannur sheep (age from 3.5 month to 11 month) were used in this study. Blood samples were collected from the jugular vein of 24 clinically healthy animals in four groups along with body weight also recorded (GI (>3-5 m), GII (>5-7m), GIII (>7-9m) and GIV (>9-11)). Triidothyroxine and Thyroxine estimation was done using immunoassay test kit method. In the present study, the mean serum Triidothyronine (ng/mL) levels ranged from 1.17 ± 0.01 to 1.80 ± 0.01 ng/mL. Positive correlation was observed between the levels of thyroid hormones (T 3) and the age of animal and body weight gain in Bannur ewes. The mean serum thyroxin (μg/dl) levels ranged from 3.98 ± 0.18 to 7.61 ± 0.05 μg/dl. T 4 concentrations elevated at premature phase, where during fattening period growing lambs needed to increase the basal metabolic rate, protein synthesis in their muscles and more of energy to achievements these biological functions, therefore plasma T 4 and glucose concentrations increased in the two last months of fattening period. The age of sheep influenced statically significantly all the investigated parameters. Blood thyroid hormones levels are considered to be good indicators of the nutritional status of an animal.
Thyroid hormone profile in dairy cattle acclimated to cold or hot environmental temperatures
European Journal of Endocrinology, 1987
Milk yields and the circulating pro file of T 4 , T 3 and rT 3 were assessed during three different seasons of the year, in first trimester lactating (L) and in dry (D) multiparous holstein cows acclimated to distinct weather conditions. Within the thermoneutral zone (18-28ºC; 40-60% RH) and regardless of their geographical location, the thyroid hormone profile in ali L-cows (n = 50) resembled the so-called euthyroid sick syndrome (T 4 , 43.7 ± 7.7 nmol/l; T 3 , 1.31±0.10 nmol/ 1 and rT 3 , 0.52 ± 0.08 nmol/I). In both groups of animals the T 3 /T4 molar ratio was similar within the entire range of climates encompassed in the study. However, both groups exhibited a significant shift in the T 3 /rT 3 molar ratio during cold (IOºC; 50%) or hot-dry (34ºC; 40%) weather conditions. This shift reaches maximum values {L, 6.5 ± l.2; D, 7.9 ± l.0 nmoles/l) under hot-humid conditions (28-42ºC; 60-90%). The relative increase ofT 3 levels from comfortable to cold or hot environmental temperatures, was significantly higher in L than D animals (30 vs 12%, respectively). Furthermore, only L-cows exhibited a significant decrease in the rT3/T 4 molar ratio during either type of thermoregulatory demands, as well as a significant increase of T4 values under heat-acclimation. These results suggest that heat-acclimation in dairy cattle <loes not depress thyroid gland activity, and lend further support to the notion that adaptive ther-Presented in part at the 25th Reunion Anual Soc Mex Nutr Endocrino!, Mazatlan, Sin. Mexico 1985.
Reproduction, Fertility and Development, 1994
Experiment 1, from 6 July 1990 (winter) to 8 November 1990 (spring), examined the effect of an early elevation of plasma thyroid hormone concentrations on the expression of seasonal changes in 20-month-old stags. Four stags were injected subcutaneously with 1 mg thyroxine (T4) daily, and four with vehicle only. Plasma T4 concentration was elevated by injection of T4; the mean concentration 24 h after injection was 192 +/- 31 nmol L-1 compared with 58 +/- 5 nmol L-1 in controls on 21 September. However, live weight, testicular diameter, plasma testosterone concentration and moulting underwent similar changes in both groups of animals. Experiment 2 tested the hypothesis that thyroid hormones are required for the expression of changes that occur during spring and early summer in red deer stags. Thyroidectomized (THX) stags (n = 4) of mixed age (> 22 months old) were given a replacement dosage of T4 or vehicle only (controls) during spring (from 7 September). T4-treated THX stags und...