Effects of thyroid hormones and prolactin on food intake and weight changes in young male reindeer (Rangifer tarandus tarandus)

1982 ◽  
Vol 60 (7) ◽  
pp. 1562-1567 ◽  
Author(s):  
Morten Ryg ◽  
Endre Jacobsen
Keyword(s):  
Weight Gain ◽  
Thyroid Hormone ◽  
Food Intake ◽  
Thyroid Hormones ◽  
Rangifer Tarandus ◽  
Hormone Secretion ◽  
Young Male ◽  
Growth Cycle ◽  
Prolactin Secretion ◽  
Weight Changes

Yearling male reindeer were treated with thyroid hormones and prolactin to see if reported seasonal variations in these hormones could participate in the control of the growth cycle in Cervidae. Both prolactin and thyroid hormone injections were followed by increased food intake. The effect was not additive, and no interactions were seen. Weight gain decreased after treatment with thyroid hormone, alone or in combination with prolactin. Weight gain increased in animals treated with prolactin alone. We conclude that changes in prolactin secretion may be important for the regulation of the growth cycle, but that the role of changes in thyroid hormone secretion is unclear.

Effects of castration on growth and food intake cycles in young male reindeer (Rangifer tarandus tarandus)

1982 ◽  
Vol 60 (5) ◽  
pp. 942-945 ◽  
Author(s):  
Morten Ryg ◽  
Endre Jacobsen
Keyword(s):  
Body Weight ◽  
Weight Gain ◽  
Food Intake ◽  
Rangifer Tarandus ◽  
Young Male ◽  
Late Summer ◽  
Growth Cycle ◽  
Rangifer Tarandus Tarandus ◽  
Cyclic Changes

To establish whether testicular factors are essential for the regulation of the growth cycle of reindeer, we investigated changes in food intake and body weight in intact and castrated males from March to December. The castrates gained less weight than the intact animals during summer, and during late summer food intake was lower in the castrates. During late September and early October, coinciding with testosterone peaks, the intact animals lost weight, whereas the weight of the castrates was stable. In spite of these differences, cyclic changes in food intake and rate of weight gain was seen also in the castrates. The regulation of the growth cycle in male reindeer can therefore only partly be dependent on testicular factors.

Seasonal changes in weight gain, growth hormone, and thyroid hormones in intact and castrated male moose (Alces alces alces)

1982 ◽  
Vol 60 (11) ◽  
pp. 2941-2946 ◽  
Author(s):  
Morten Ryg
Keyword(s):  
Growth Hormone ◽  
Weight Gain ◽  
Thyroid Hormone ◽  
Food Intake ◽  
Thyroid Hormones ◽  
Seasonal Changes ◽  
Alces Alces ◽  
Serum Concentrations ◽  
Rapid Weight Gain ◽  
Thyroid Hormone Levels

To elucidate possible endocrine mechanisms in the control of cyclic weight gain in moose, serum concentrations of growth hormone (GH), thyroxine (T4), and triiodothyronine (T3) were recorded during the year in two intact and one castrated male moose. Changes in the levels of these hormones were compared with changes in weight gain. Growth hormone often increased to peak values in April or May, but was generally low throughout the period of greatest weight gain. Thyroid hormone levels increased in spring and decreased in autumn, corresponding to onset and cessation of rapid weight gain. Changes in triiodothyronine levels may have been secondary to changes in food intake.

Immunization against vasoactive intestinal peptide does not affect thyroid hormone secretion or thyroid blood flow

1994 ◽  
Vol 266 (6) ◽  
pp. E905-E913
Author(s):  
M. Michalkiewicz ◽  
L. J. Huffman ◽  
M. Dey ◽  
G. A. Hedge
Keyword(s):  
Thyroid Hormone ◽  
Thyroid Hormones ◽  
Vasoactive Intestinal Peptide ◽  
Iodine Deficiency ◽  
Binding Capacity ◽  
Hormone Secretion ◽  
Passive Immunization ◽  
Male Rats ◽  
Blood Levels ◽  
Blood Flows

Vasoactive intestinal peptide (VIP) is present in thyroid parasympathetic nerves. To assess the involvement of endogenous VIP in the regulation of thyroid function, blood levels of thyroid hormones and thyroid blood flows (TBF) were measured after systemic immunization against VIP or after transection of the superior laryngeal nerves in male rats, which reduced the thyroid content of VIP but did not affect blood levels of thyroid hormones or TBF. Anti-VIP monoclonal antibody or anti-VIP serum was used for immunization against VIP in normal rats. In addition, VIP antibody was given to rats fed an iodine-deficient diet for 5 days to examine the involvement of this peptide in iodine deficiency-induced increases in TBF. Effects were measured at different times (90 s, 30 min, 1 h, and 5 days) after immunoneutralization, but none of these treatments changed blood levels of thyroid hormones or TBF in normal or iodine-deficient rats. However, passive immunization against VIP was associated with a high binding capacity of rat plasma to VIP, and this treatment reduced blood levels of prolactin as well as blood flows to the duodenum, stomach, and lung. These findings suggest that the VIP present in thyroid nerves is not involved in maintaining basal thyroid hormone secretion or TBF and that this neuropeptide does not mediate thyroid vascular adjustments to dietary iodine deficiency.

scholarly journals Sexual dimorphism in the acute effects of secondhand smoke on thyroid hormone secretion, inflammatory markers and vascular function

2008 ◽  
Vol 294 (2) ◽  
pp. E456-E462 ◽  
Author(s):  
Andreas D. Flouris ◽  
Giorgos S. Metsios ◽  
Athanasios Z. Jamurtas ◽  
Yiannis Koutedakis
Keyword(s):  
Blood Pressure ◽  
Thyroid Hormone ◽  
Thyroid Hormones ◽  
Systolic Blood Pressure ◽  
Inflammatory Cytokines ◽  
Secondhand Smoke ◽  
Vascular Function ◽  
Hormone Secretion ◽  
Gonadal Hormones ◽  
Free Thyroxine

Experimental evidence for the physiological effects of secondhand smoke (SHS) is limited, although it affects millions of people globally and its prevalence is increasing, despite currently adopted antismoking measures. Also, scarce evidence suggests that the effects of SHS may be more pronounced in men. We conducted a randomized single-blind crossover study to investigate the sex-specific SHS effects in a controlled simulated bar/restaurant environment on gonadal and thyroid hormones, inflammatory cytokines, and vascular function. Twenty-eight (women = 14) nonsmoking adults underwent a 1-h exposure to moderate SHS and a 1-h control trial. Serum and urine cotinine, gonadal and thyroid hormones, inflammatory cytokines, heart rate, and arterial blood pressure were assessed before exposure and immediately after in both trials. Results showed that testosterone ( P = 0.019) and progesterone ( P < 0.001) in men and 17β-estradiol ( P = 0.001) and progesterone ( P < 0.001) in women were significantly decreased after SHS. In men, SHS was accompanied by increased free thyroxine ( P < 0.001), triiodothyronine ( P = 0.020), and decreased the triiodothyronine-to-free thyroxine ratio ( P = 0.033). In women, significant SHS-induced change was observed only in free thyroxine ( P = 0.010), with considerable sex variation in free thyroxine and triiodothyronine and a decrease in luteinizing hormone ( P = 0.026) and follicle-stimulating hormone ( P < 0.001). After SHS, IL-1β ( P = 0.001) and systolic blood pressure ( P = 0.040) were increased in men but not women. We concluded that a 1-h SHS exposure at bar/restaurant levels is accompanied by decrements in gonadal hormones in both sexes and marked increases in thyroid hormone secretion, IL-1β production, and systolic blood pressure in men.

Manipulation of thyroid hormones in ruminants - a tool to understand their physiological role and identify their potential for increasing production efficiency

2002 ◽  
Vol 53 (3) ◽  
pp. 259 ◽  
Author(s):  
D. Villar ◽  
S. M. Rhind ◽  
J. R. Arthur ◽  
P. J. Goddard
Keyword(s):  
Thyroid Hormone ◽  
Thyroid Hormones ◽  
Production Efficiency ◽  
Hormone Replacement ◽  
Animal Health ◽  
Hormone Secretion ◽  
Plasma Concentrations ◽  
Physiological Role ◽  
Antithyroid Drugs ◽  
Few Data

Manipulations of thyroid hormone secretion and function can be used to cure thyroidal deficiencies or overactivity and as a tool to investigate their physiological roles and identify potential protocols for enhancing animal performance. An essential approach to the investigation of thyroid hormone action involves the induction of hypothyroidal states. Methods of inducing hypothyroidal states in ruminants include thyroidectomy and treatment with thionamides. There are few data concerning the induction of an optimal degree of hypothyroidism for the study of thyroid function in ruminants, unlike the situation in rodents. The effects of hypothyroidism on the physiology of ruminants, and the relative merits of thyroidectomy or of treatment with thionamides to manipulate thyroid hormone profiles in them, are reviewed and discussed. Thyroidectomy in ruminants induces an acute, irreversible, hypothyroidal state. It also has indirect, predominantly adverse, effects on many physiological processes and impairs health. Thus, thyroidectomised (THX) animals cannot be sustained for long-term studies without thyroid hormone replacement. Antithyroid drugs of the thionamide class, on the other hand, have been used with success to induce varying degrees of hypothyroidism, predominantly less severe than those induced by thyroidectomy. The changes induced by drugs are reversible upon withdrawal of treatment. However, treatment may require daily administration of the drug for several weeks before stable plasma concentrations of thyroid hormone are achieved. Furthermore, at high doses, these drugs can have toxic side effects. It is concluded that the treatment regime of choice will depend on the objectives of the individual study. Knowledge of the activities of thyroid hormone metabolising, deiodinase enzymes in the target tissues is also required if the actions of some of these drugs, their physiological roles in modulation of the thyroid hormones, and, crucially, their potential effects on animal health and production are to be properly understood and exploited.

COMPARATIVE EFFECTS OF SUCROSE AND CORNSTARCH IN LOW-PROTEIN DIETS FED TO RATS EXPOSED TO COLD

1965 ◽  
Vol 43 (2) ◽  
pp. 241-249
Author(s):  
J. R. Beaton ◽  
J. F. Sangster
Keyword(s):  
Body Weight ◽  
Weight Gain ◽  
Food Intake ◽  
Body Weight Gain ◽  
Young Male ◽  
Male Rats ◽  
Low Protein ◽  
Environmental Temperatures ◽  
Protein Diets ◽  
Starch Diet

Young male rats were fed one of three low-protein (5% casein) diets differing in the source of carbohydrate (sucrose, equal parts sucrose and cornstarch, or cornstarch) or a 20% casein (sucrose) diet at environmental temperatures of 24 °C or 5 °C. Replacement of sucrose with starch appeared to have a small but significant effect in increasing body weight gain for 15 days (but not the next 28 days) at 24 °C and also in animals exposed to cold for 28 days after a 15-day feeding period at 24 °C. In disagreement with results reported by Andik et al., cold exposure, although significantly increasing body weight gain and food intake in rats fed the 5% casein – starch diet, did not elicit a weight gain as great as that observed in 20% casein-fed animals at either 24 °C or 5 °C. The 24-hour food intake following a 24-hour fast exceeded the intake on the day before fasting on all diets for animals maintained at 5 °C but not 24 °C. The immediate ([Formula: see text] hour) and 24-hour food intakes of rats at 5 °C exceeded those of comparable dietary groups at 24 °C. At 5 °C, the 24-hour food intake, following the fast, of rats fed the 5% casein – starch diet exceeded that of the 20% casein-fed controls.

Causes and laboratory investigation of hypothyroidism

2011 ◽  
pp. 530-537 ◽  
Author(s):  
Ferruccio Santini ◽  
Aldo Pinchera
Keyword(s):  
Thyroid Hormone ◽  
Thyroid Gland ◽  
Thyroid Hormones ◽  
Thyroid Hormone Receptor ◽  
Hormone Secretion ◽  
Thyroid Tissue ◽  
Clinical Manifestations ◽  
Primary Hypothyroidism ◽  
Central Hypothyroidism ◽  
Resistance To Thyroid Hormones

Hypothyroidism is the clinical state that develops as a result of the lack of action of thyroid hormones on target tissues (1). Hypothyroidism is usually due to impaired hormone secretion by the thyroid, resulting in reduced concentrations of serum thyroxine (T4) and triiodothyronine (T3). The term primary hypothyroidism is applied to define the thyroid failure deriving from inherited or acquired causes that act directly on the thyroid gland by reducing the amount of functioning thyroid tissue or by inhibiting thyroid hormone production. The term central hypothyroidism is used when pituitary or hypothalamic abnormalities result in an insufficient stimulation of an otherwise normal thyroid gland. Both primary and central hypothyroidism may be transient, depending on the nature and the extent of the causal agent. Hypothyroidism following a minor loss of thyroid tissue can be recovered by compensatory hyperplasia of the residual gland. Similarly, hypothyroidism subsides when an exogenous inhibitor of thyroid function is removed. Peripheral hypothyroidism may also arise as a consequence of tissue resistance to thyroid hormones due to a mutation in the thyroid hormone receptor. Resistance to thyroid hormones is a heterogeneous clinical entity with most patients appearing to be clinically euthyroid while some of them have symptoms of thyrotoxicosis and others display selected signs of hypothyroidism. The common feature is represented by pituitary resistance to thyroid hormones, leading to increased secretion of thyrotropin that in turn stimulates thyroid growth and function. The variability in clinical manifestations depends on the severity of the hormonal resistance, the relative degree of tissue hyposensitivity, and the coexistence of associated genetic defects (see Chapter 3.4.8).

Seasonal changes in weight gain, growth hormone, and thyroid hormones in male red deer (Cervus elaphus atlanticus)

1982 ◽  
Vol 60 (11) ◽  
pp. 2577-2581 ◽  
Author(s):  
Morten Ryg ◽  
Rolf Langvatn
Keyword(s):  
Growth Hormone ◽  
Weight Gain ◽  
Food Intake ◽  
Thyroid Hormones ◽  
Cervus Elaphus ◽  
Seasonal Changes ◽  
Red Deer ◽  
Antler Growth ◽  
Gain Peak

To elucidate possible endocrine mechanisms in the control of the weight cycle of red deer, we recorded seasonal changes in the concentrations of growth hormone (GH), thyroxine (T4), and triiodothyronine (T3) in serum. T3 and T4 were analyzed with specific radioimmunoassays, GH was analyzed with a hetereologous radioimmunoassay. Changes in the levels of these hormones were compared with changes in weight gain. T3 levels were high in summer and low in winter, corresponding to changes in weight gain. Peak values (1.75–4.82 nmol/L) were found in May or June, nadirs occurred in April (0.22–1.78 nmol/L) or October–November (0–1.19 nmol/L). GH levels increased to peak values, 20–53 ng/mL, in April to June, but were low during most of the period of fast weight gain. There were no consistent changes in T4 levels corresponding to the weight cycle. We conclude that the GH peaks following the casting of old antlers may be related to the onset of antler growth. Seasonal changes in T3 levels may be secondary to changes in food intake.

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