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At least 19 recordsLinked to original sources
PubMed1987

Plasma thyroid hormones, thyroid stimulating hormone, and insulin during acute hypometabolic states in man.

Acute behavioral rest states in man are associated with marked hormonal and metabolic changes. In order to complete a hormonal profile of these states and to identify possible metabolic regulators, we measured thyroid hormones (T3 and T4), thyroid stimulating hormone (TSH), and insulin during the stylized mental practice of "transcendental mediation" (TM) and during ordinary unstylized eyes closed rest. Except for TSH, which declined acutely, hormone levels were normal and stable throughout the experiment. The stability of T3 and T4, and insulin make it unlikely that these hormones regulate the acute metabolic changes associated with these behavioral states. Decreased TSH, along with stable thyroid hormone levels, may suggest change of the set point for feedback control of TSH secretion during TM and is consistent with primarily neural modulation of TSH secretion by this behavior.

Adult↗
PubMed1982

Effect of parenteral nutrition on the blood levels of insulin, glucagon, growth hormone, thyroid hormones and cortisol in catabolic patients.

The changes in plasma insulin (IRI) glucagon (IRG), IRI:IRG ration, growth hormone (HGH), cortisol and thyroid hormones during two different but isocaloric parenteral nutrition regimens were investigated in 11 malnourished patients and 21 postoperative patients. The nutrition program which used glucose as a non-nitrogen energy source favoured anabolism by a higher rise in plasma IRI and by a higher rise in the initially low plasma IRI:IRG ratio in both malnourished and postoperative patients more than the alimentation regimen with glucose and lipid. The glucose program augmented the IRI:IRG ratio to an average of 5.5 +/- 1.2 (SEM) in malnourished patients and to 8.4+/-2.7 in postoperative patients. The corresponding values for the glucose-lipid program were 3.9+/- 1.0 and 1.9 +/- 0.4. In malnourished patients the difference between the anabolic effect of these nutrition regimens was further increased by a fall in the plasma HGH level to 0.7 +/- 0.3 microgram/l during fat infusion. Over a period of four days both alimentation programs similarly increased in the initially low serum T3 and free T3 index to the normal reference interval and decreased serum rT3 to a subnormal level (0.18+/-0.7 nmol/l) in malnourished patients. In postoperative patients the only change in thyroid hormones which was dependent on the four-day parenteral nutrition was the decrease in the initially elevated serum rT3 to the normal reference interval by both alimentation programs (by 54% in the glucose and by 30% in the glucose-lipid program).

Adult↗
PubMed1979

Seasonal effects of tropical climate on shaded and nonshaded cows as measured by rectal temperature, adrenal cortex hormones, thyroid hormone, and milk production.

Rectal temperatures and hormone concentrations were monitored at intervals of 2 to 3 weeks, and milk, milk fat, and California mastitis test scores at intervals of 1 week in five shaded and in four nonshaded early lactation cows. Measurements were taken from September to December in the mildly heat stressing climate of Oahu, Hawaii. The daily ambient temperature flux ranged from 22 C to 29 C in September to 20 C to 25 C in December. Average daily temperature-humidity index (THI) values were 75 to 70 for September and December, respectively. Average daily THI values were correlated with rectal temperatures in nonshaded cows and were negatively correlated with plasma adrenal cortex hormones (corticoids) in shaded cows, plasma thyroid hormone in shaded and nonshaded cows, and with milk production in nonshaded cows. Estimated milk production decline per unit increase in THI was 0.32 kg. Nonshaded cows had higher rectal temperatures, a trend for lower plasma corticoids, produced less milk and milk fat, and had higher California mastitis test scores. Shaded cows maintained a higher fat percentage at THI above 74. Average plasma thyroid hormone values were not different between treatment groups. Both groups failed to attain normal rectal temperatures at night. Afternoon rectal temperatures were more highly correlated with the rectal temperature with which the cow started the day than they were with the THI of the day itself.

Adrenal Cortex Hormones↗
PubMed1987

Theophylline treatment in the neonate with apnea: effect on growth hormone, thyroid hormone and TRH induced TSH secretion.

Caffeine has been shown to markedly alter growth hormone (GH), thyroid stimulating hormone (TSH), and thyroid hormones in animal studies. Similar studies in the human are lacking. To determine the effect of theophylline treatment on endocrine function in neonates with apnea, 10 infants were studied prospectively pretreatment, immediately following therapeutic blood levels of theophylline, at 2, 4, and 6 weeks thereafter and finally 2 weeks after discontinuation of theophylline. T4, free T4, T3, GH, and basal and stimulated TSH were measured at each study period. Results show no significant difference consequent to theophylline therapy on basal thyroid or GH secretion and thyrotropin-releasing hormone (TRH) induced TSH response at any study interval. We conclude there is no evidence to suspect abnormality occurring in growth, thyroid function and GH secretion in neonates receiving theophylline for breathing disorders.

Apnea↗
PubMed1992

Changes in thyroid hormones, thyroid stimulating hormone and cortisol in acute spinal cord injury.

To determine the hormonal response to acute spinal cord injury, serial serum samples were collected from 18 patients with acute spinal cord injury and from 14 control patients with spinal fractures without cord injury. The first sample was taken within 24 hours of injury, the second at 24-48 hours; and the third at 7 days for determination of thyroxine (T4), free T4 (FT4), triiodothyronine (T3), reverse T3 (rT3), T3 uptake (T3U), thyroid stimulating hormone (TSH), thyroxine binding globulin (TBG), growth hormone (GH), cortisol, and insulin. Significant increases were observed in rT3 levels and transient changes were observed in the T4 and T3 levels in the spinal cord injured group but not in the group with spinal fractures alone. The changes in the spinal cord injured patients are consistent with the 'low T3 syndrome'. However, the persisting rise of rT3 at 7 days was an unexpected finding. In addition to the cord injury, these changes may also be related to dexamthasone administration and nutritional factors.

Acute Disease↗
PubMed1988

The relationship between insulin-like growth factor-1, growth hormone, thyroid hormones and insulin in chickens selected for growth.

The concentrations of circulating insulin-like growth factor I, growth hormone, insulin and thyroid hormones were measured in broilers selected for an increase in growth, broilers in which selection pressure was relaxed and in White Leghorns. Growth hormone levels increased in all lines between 3 and 4 weeks of age followed by a decline to adult levels. The lines with the slowest rate of growth had the highest growth hormone concentrations. Insulin-like growth factor I concentrations increased significantly in all three lines of birds during the 10 weeks of study and was significantly correlated with the increase in body weight. There were no consistent differences in plasma IGF-1 levels between the lines. Thyroxine levels increased consistently throughout the study but the levels of triiodothyronine decreased between 5 and 6 weeks of age in all lines. There were no consistent changes in plasma insulin levels. The highest rate of growth in these animals is accompanied by an increase in growth hormone concentration followed by an increase in plasma IGF-1. However, despite differences in plasma growth hormone, plasma concentrations of IGF-1 are not different between lines and are not related to between line differences in growth rate.

Animals↗
PubMed1996

Serum levels of sex hormones, thyroid hormones, growth hormone, IGF I, and cortisol and their relations to body fat distribution in healthy women dependent on their menopausal status.

The relations between 10 anthropometric variables describing the amount of adipose tissue and the serum levels of thyroxine, triiodothyronin, thyroid stimulating hormone, estradiol, progesterone, 17-hydroxyprogesterone, prolactin, luteinizing hormone, follicle stimulating hormone, DHEA-S, androstendion, testosterone, sex hormone binding globulin, growth hormone, IGF I as well as cortisol were investigated in 39 premenopausal and 38 postmenopausal women. Several statistically significant correlations between hormonal parameters and the amount and the distribution of subcutaneous fat tissue were found for the premenopausal group. The postmenopausal probands, however, showed fewer statistically significant connections between the two trait systems. The correlation patterns in both proband groups resembled each other. Only with regard to the gonadotropines (LH and FSH) a difference in the algebraic sign of the correlation coefficients can be observed for pre- and postmenopausal probands. The multiple regression analysis corroborated the hypothesis that hormonal parameters are responsible for somatic changes after menopause.

Adipose Tissue↗
PubMed1990

Influence of chronic melatonin implantation on circulating levels of catecholamines, growth hormone, thyroid hormones, glucose, and free fatty acids in the pigeon.

Subcutaneous implantation of melatonin pellets (2 mg melatonin + 30 mg beeswax) for a period of 12 weeks, with reinforcement of implants every 2 weeks, caused significant increases in plasma levels of glucose and growth hormone (GH). Plasma levels of thyroxine (T4) were lower and the triiodothyronine (T3)/T4 ratio was higher in the melatonin-treated pigeons. However, melatonin treatment produced no significant effect on plasma levels of free fatty acids (FFA), T3, epinephrine (E), and norepinephrine (NE), although trends (P greater than 0.05) toward slight increases in FFA and T3 and decreases in E and NE were apparent. Since melatonin treatment caused increases in the levels of plasma glucose and GH and not in those of the other substances measured, it is suggested that melatonin enhances carbohydrate metabolism in preference to lipid metabolism in resting pigeons during the day (photophase) when pineal and circulating levels of melatonin are normally lower than during night (scotophase).

Animals↗
PubMed1987

Influence of orally administered thyrotropin-releasing hormone on plasma growth hormone, thyroid hormones, growth, feed efficiency, and organ weights of broiler chickens.

Thyrotropin-releasing hormone (TRH) was administered continuously or intermittently in the drinking water of male broiler chickens from 2 to 21 days of age. Intermittent administration of TRH was accomplished by giving birds access to the solution for 2 hr, then removing it for 2 hr, with six repetitions of this procedure each 24 hr. The TRH concentration was such that the birds each would ingest 10 to 20 micrograms of the material during each 2-hr period that it was available. Plasma growth hormone (GH) levels were elevated within 30 min after an episode of TRH administration at 2, 7, and 14 days of age but not at 21 days. Continuous administration of TRH had no effect on GH in plasma at any age. Thyroxine concentrations in plasma were increased within 30 min of first exposure to TRH at 2 days of age, but they were unaffected by intermittent episodes of TRH at 7, 14, and 21 days of age. Triiodothyronine concentrations in plasma were unaffected by TRH at any age. Even though intermittent TRH administration elicited significant elevation in plasma GH for at least 14 days of the experiment, it had no effect on body weight, feed consumption, or weight of the gastrocnemius muscle, the pectoralis major muscle, liver, tibia, or abdominal fat pad.

Administration, Oral↗
PubMed1998

Changes in circulating LH, sex steroid hormones, thyroid hormones and corticosterone in relation to breeding and molting in captive humboldt penguins (Spheniscus Humboldti) kept in an outdoor open display.

Penguins are highly adapted to marine life. Their hydrodynamic efficiency depends on feathers which wear with age and need to be replaced regularly. During molting, penguins can not enter the sea to forage and are forced to fast. Therefore the duration of molting is necessarily brief. To better understand molting in penguins, we collected plasma samples from 16 (8 pairs) Humboldt penguins kept in an open display pen at Tokyo Sea Life Park from May to September, 1994 and estimated circulating concentrations of LH, testosterone, estradiol, thyroxine (T4), triiodothyronine (T3) and corticosterone. Body mass was also measured at each blood sampling. Throughout the year, reproductive activities (egg laying, incubation, hatching and rearing) and molting were observed and recorded. Humboldt penguins maintained reproductive activity from January to December except during molting. Each pair started molting between the end of July and early August; usually males started earlier. The duration of molting was 13.4 +/- 0.8 days for males and 12.9 +/- 0.3 days for females. Body masses were highest just before the start of molting in both sexes. Plasma concentrations of LH were high, (> 2 ng/ml) in May in both sexes, then gradually decreased, to 0.53 +/- 0.38 ng/ml in males and 0.72 +/- 0.11 ng/ml in females by the end of July. Testosterone and estradiol concentrations in plasma decreased and were lowest during molting. On the other hand, plasma concentrations of T4 were low until early July (ca. 20 ng/ml) and then doubled within 10 days; the high levels were maintained for one month and then decreased greatly in males and slightly in females. When the plasma concentrations of T4 started to decrease, plasma concentrations of LH increased. Changes in plasma T3 were not consistent with molting. These results indicate that the decrease of plasma levels of sex steroid hormones and the sharp increase of T4 induced molting, which lasted only for a short period.

Adaptation, Physiological↗
PubMed1994

The hormonal regulation of the oestrogen receptor in rat liver: an interplay involving growth hormone, thyroid hormones and glucocorticoids.

The regulation of the formation of the hepatic oestrogen receptor (ER) in adult female rats was studied by assaying steady state levels of ER and ER messenger RNA under different endocrine conditions. Hypophysectomy (HX) drastically reduced ER levels from 67.5 +/- 7.9 to 8.4 +/- 0.5 (means +/- S.E.M.) fmol/mg cytosolic protein. Continuous infusion of growth hormone (GH) to HX animals tripled ER and doubled ER mRNA levels. Treatment with triiodothyronine (T3) in a high dose (10 micrograms/day) doubled ER mRNA levels. The effects of T3 were dose-dependent, since a lower dose (1 microgram/day) increased neither ER nor ER mRNA levels. ER mRNA concentrations were increased by GH to 481 +/- 44% and by T3 to 372 +/- 35% of HX control levels 4 h after single injections of the hormones in HX animals. The glucocorticoid dexamethasone (DEX) alone increased neither ER nor ER mRNA levels in HX animals. DEX and GH in combination increased ER 5-fold and ER mRNA 2-fold compared with control levels in HX animals, whereas DEX and T3 in combination increased neither ER nor ER mRNA levels. Treatment with prolactin affected neither ER nor ER mRNA levels in HX rats. Insulin-like growth factor I (IGF-I) mRNA and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) mRNA levels were measured. GAPDH mRNA levels were increased 2.5-fold in HX rats by DEX and T3 in combination and almost 2-fold by DEX and GH in combination. IGF-I mRNA levels in HX rats were increased 4.5-fold by continuous infusion of GH alone, 6-fold by GH and T3 in combination, and 2.5-fold by GH and DEX in combination. These data indicate that both GH and T3 act directly on the liver to increase ER mRNA levels. GH, the most important of these hormones, also acts at the translational and/or post-translational level to increase ER protein levels. DEX treatment suppresses the stimulatory effects of T3, but not of GH.

Animals↗
PubMed1981

Associations between sex hormones, thyroid hormones and lipoproteins.

1. A study of 150 middle-aged male industrial employees has shown significant positive correlations between plasma levels of high-density-lipoprotein (HDL) cholesterol and both serum testosterone and alcohol intake, and significant negative correlations between HDL cholesterol and both serum thyroxine and obesity. These associations persist when examined by multiple linear regression, indicating their independence. 2. Significant positive correlations are also shown between plasma triglyceride levels and both obesity and serum thyrotropic hormone (TSH) levels. 3. There are no evident relationships between serum oestrone or oestradiol and either HDL cholesterol or triglyceride levels, nor between any of the hormones and either total or low-density-lipoprotein (LDL) cholesterol. 4. Because of the potential importance in relation to coronary heart disease prevention, further studies are needed to try and understand the mechanisms of the associations between HDL cholesterol and obesity, alcohol intake and thyroid and sex hormone levels.

Alcohol Drinking↗
PubMed1989

Smoltification and seawater adaptation in coho salmon (Oncorhynchus kisutch): plasma prolactin, growth hormone, thyroid hormones, and cortisol.

The status of circulating growth hormone and prolactin during the parr-smolt transformation and during seawater adaptation of coho salmon (Oncorhynchus kisutch) was investigated in relation to changes in plasma levels of thyroxine, triiodothyronine, and cortisol, and in hypoosmoregulatory ability. Sampling (biweekly or monthly) occurred between early February and October. When peak hypoosmoregulatory ability was achieved (mid-April), one group of fish was acclimated to seawater over a period of 18 hr and was sampled 1, 3, and 7 days after the introduction of fish to seawater and biweekly thereafter. Plasma prolactin levels rose steadily from the first sampling date to a peak of 15 ng/ml in early April, declined rapidly, and remained low until June when a second increase occurred. Prolactin declined to 2 ng/ml within 1 day of the beginning of seawater adaptation. Growth hormone increased twofold from February to late March, and achieved plateau levels of 20 ng/ml in the period from mid-April to July and then gradually declined to 10 ng/ml in September and October. Plasma levels of growth hormone in seawater-acclimated fish were similar to those of freshwater coho, but with larger fluctuations; no increase was apparent during the first week of seawater acclimation. Plasma cortisol and plasma triiodothyronine increased at the same time as plasma growth hormone; increases in plasma thyroxine occurred later. In general, both growth hormone and cortisol levels were elevated when hypoosmoregulatory ability was high. Conversely, prolactin levels generally showed a negative relationship with hypoosmoregulatory ability.

Acclimatization↗
PubMed1997

Thyrotropin regulation by thyroid hormone in thyroid hormone receptor beta-deficient mice.

Thyroid hormone responsive genes can be both positively and negatively regulated by thyroid hormone. TSH is down-regulated by thyroid hormone and rises during thyroid hormone deprivation. Because both thyroid hormone receptor (TR) alpha and beta genes are expressed in the pituitary gland, it is unclear what the relative roles of TR alpha and TR beta are in TSH regulation. Experiments using over expression of artificial genes have yielded conflicting results. The TR beta knock-out mouse that lacks both TR beta1 and TR beta2 isoforms provides a model to examine the role of these receptors in TSH regulation. TR beta deficient (TR beta-/-) and wild-type (TR beta+/+) mice of the same strain were deprived of thyroid hormone by feeding them a low iodine diet containing propylthiouracil and were then treated with different doses of L-T3 and L-T4. Thyroid hormone deprivation rapidly increased the serum TSH level in both TR beta+/+ and TR beta-/- mice, reaching a similar level in the absence of thyroid hormone. In contrast, the decline of serum TSH by treatment with both L-T3 and L-T4 was severely blunted in TR beta-/- mice, and full suppression was not achieved with the maximal L-T3 dose of 25 microg/day x mouse. These data indicate that TR beta is not required for the up-regulation of TSH in thyroid hormone deficiency. However, although TR alpha alone can mediate thyroid hormone induced TSH suppression, TR beta enhances the sensitivity of TSH down-regulation and may be essential for the complete suppression of TSH.

Animals↗
PubMed2000

The mechanism of action of thyroid hormones.

Thyroid hormone is essential for normal development, differentiation, and metabolic balance. Thyroid hormone action is mediated by multiple thyroid hormone receptor isoforms derived from two distinct genes. The thyroid hormone receptors belong to a nuclear receptor superfamily that also includes receptors for other small lipophilic hormones. Thyroid hormone receptors function by binding to specific thyroid hormone-responsive sequences in promoters of target genes and by regulating transcription. Thyroid hormone receptors often form heterodimers with retinoid X receptors. Heterodimerization is regulated through distinct mechanisms that together determine the specificity and flexibility of the sequence recognition. Amino-terminal regions appear to modulate thyroid hormone receptor function in an isoform-dependent manner. Unliganded thyroid hormone receptor represses transcription through recruitment of a corepressor complex, which also includes Sin3A and histone deacetylase. Ligand binding alters the conformation of the thyroid hormone receptor in such a way as to release the corepressor complex and recruit a coactivator complex that includes multiple histone acetyltransferases, including a steroid receptor family coactivator, p300/CREB-binding protein-associated factor (PCAF), and CREB binding protein (CBP). The existence of histone-modifying activities in the transcriptional regulatory complexes indicates an important role of chromatin structure. Stoichiometric, structural, and sequence-specific rules for coregulator interaction are beginning to be understood, as are aspects of the tissue specificity of hormone action. Moreover, knockout studies suggest that the products of two thyroid hormone receptor genes mediate distinct functions in vivo. The increased understanding of the structure and function of thyroid hormone receptors and their interacting proteins has markedly clarified the molecular mechanisms of thyroid hormone action.

Animals↗
PubMed1999

Thyroid hormone and thyroid hormone analogues in the treatment of heart failure.

The thyroid hormone analogue DITPA is a promising potential new treatment for heart failure. Although the mechanism of action is incompletely determined, it is clear that DITPA improves systolic as well as diastolic function. It is also clear that the effects of DITPA are intrinsic to the muscle and not the result of changes in the structure or geometry of the left ventricle. On the basis of these experimental studies, we applied to the USA Food and Drug Administration for an Investigational New Drug application to study the use of DITPA in patients. These studies are currently in progress. While we await the outcome of these clinical trials, it is important to emphasize that even if the end-point is not a new drug to treat heart failure, our investigations are based on a systematic evaluation integrating biochemistry and physiology. We believe that this is the way to approach the problem of developmental pharmacology.

Animals↗