Seasonal influence on thyroidal response to thyrotrophin-releasing hormone in cattle and buffaloes

1986 ◽  
Vol 108 (1) ◽  
pp. 57-61 ◽  
Author(s):  
M. L. Khurana ◽  
M. L. Madan
Keyword(s):  
Environmental Conditions ◽  
Plasma Levels ◽  
Biphasic Response ◽  
Seasonal Influence ◽  
Thyrotrophin Releasing Hormone ◽  
Releasing Hormone ◽  
Murrah Buffaloes ◽  
Significant Difference

ABSTRACT The effect of thyrotrophin-releasing hormone (TRH) on the circulating plasma levels of tri-iodothyronine (T3) and thyroxine (T4) was determined in the same group of animals (four cattle and four Murrah buffaloes) during hot dry (HD), hot humid (HH) and cold environmental conditions. Plasma T3 and T4 concentrations were measured during 2 h before and up to 12 h after the administration of TRH (200 μg i.v.). In the preinjection period in both cattle and buffaloes T3 levels were significantly lower in HH conditions. No significant difference in basal (preinjection) T3 levels was observed during HD and cold seasons in cattle. The highest T3 levels were obtained in buffaloes during HD season with intermediate values during the cold months. Plasma T4 levels in these animals were reversed during HD and HH months. In both cattle and buffaloes there was a biphasic response of T3 and T4 to TRH treatment and this varied with time and in size. The season significantly affected the T3 response to TRH in cattle and buffaloes but the T4 response differed in the two species. The ratio of T4/T3 was higher during HH condition compared with other seasons in both cattle and buffaloes. The climate significantly affected the thyroidal response to TRH. J. Endocr. (1986) 108, 57–61

EVIDENCE FOR THE INVOLVEMENT OF HYPOTHALAMIC DOPAMINE AND THYROTROPHIN-RELEASING HORMONE IN SUCKLING-INDUCED RELEASE OF PROLACTIN

1981 ◽  
Vol 91 (2) ◽  
pp. 213-223 ◽  
Author(s):  
W. J. DE GREEF ◽  
T. J. VISSER
Keyword(s):  
Nerve Stimulation ◽  
Plasma Levels ◽  
Plasma Prolactin ◽  
Prolactin Release ◽  
Thyrotrophin Releasing Hormone ◽  
Dopamine Infusion ◽  
Releasing Hormone ◽  
Peripheral Plasma ◽  
Transient Decrease ◽  
Hypothalamic Dopamine

The changes in adenohypophysial and hypothalamic content and in hypothalamic release of dopamine and thyrotrophin-releasing hormone (TRH) into the hypophysial portal system during the suckling-induced release of prolactin were investigated. An increase in peripheral plasma levels of prolactin was induced by mammary nerve stimulation in urethane-anaesthetized and by suckling in unanaesthetized lactating rats. In the unanaesthetized rat, suckling caused a decrease of dopamine levels in hypothalamus and adenohypophysis and a short-lasting small increase in hypothalamic TRH. Mammary nerve stimulation induced a transient decrease in dopamine levels and an increase in TRH levels in hypophysial stalk blood. To assess the significance of the observed changes in dopamine and TRH levels for prolactin release, these changes in dopamine and TRH were mimicked in lactating rats anaesthetized with urethane and pretreated with α-methyl-p-tyrosine (AMpT, a competitive inhibitor of catecholamine synthesis). Reducing hypothalamic dopamine secretion by treatment with AMpT increased peripheral plasma levels of prolactin from 15 to 477 ng/ml; an infusion with dopamine, resulting in plasma levels similar to those measured in hypophysial stalk plasma, reduced plasma levels of prolactin to 127 ng/ml. Neither a 50% reduction in dopamine infusion rate for 15 min nor administration of 100 ng TRH caused an appreciable change in plasma prolactin levels. However, when dopamine infusion was reduced by 50% for 15 min just before TRH was injected, then an increase in plasma levels of prolactin from 172 to 492 ng/ml was observed. Thus, the effectiveness of TRH in releasing prolactin in the lactating rat was enhanced when a transient decrease of dopamine levels occurred before treatment with TRH. It is concluded that the changes observed in dopamine and TRH levels in hypophysial stalk blood are involved in the suckling-induced prolactin release in an important manner.

Effect of somatostatin and thyrotrophin-releasing hormone on the levels of growth hormone in the circulation of the chronically catheterized pig fetus in utero

1985 ◽  
Vol 106 (1) ◽  
pp. 121-124 ◽  
Author(s):  
G. S. G. Spencer ◽  
G. J. Garssen ◽  
B. Colenbrander ◽  
J. C. Meijer
Keyword(s):  
Growth Hormone ◽  
Plasma Levels ◽  
In Utero ◽  
Thyrotrophin Releasing Hormone ◽  
Releasing Hormone ◽  
Hormone Levels ◽  
Saline Administration ◽  
Treatment Administration ◽  
Fetal Pig

ABSTRACT The effects of i.v. administration of thyrotrophin-releasing hormone (TRH) and of somatostatin on circulating plasma levels of porcine GH in the chronically catheterized pig fetus have been examined. Growth hormone levels increased markedly (P<0·01) following TRH administration, but there was no change in thyroxine levels by 1 h after treatment. Administration of somatostatin caused a significant (P<0·05) decrease in mean GH levels, but the response was variable between pigs. Saline administration had no significant effect on GH levels. These results suggest that the mechanisms regulating postnatal GH release are present in the fetal pig, but may not be fully developed 8–12 days before delivery. J. Endocr. (1985) 106, 121–124

INTRAVENOUS AND PERORAL TRH STIMULATION IN SPORADIC ATOXIC GOITRE

1977 ◽  
Vol 85 (3) ◽  
pp. 508-514 ◽  
Author(s):  
C. Kirkegaard ◽  
J. Faber ◽  
T. Friis ◽  
U. Birk Lauridsen ◽  
P. Rogowski ◽  
...  
Keyword(s):  
High Frequency ◽  
Diagnostic Value ◽  
Stimulation Test ◽  
Trh Test ◽  
Thyrotrophin Releasing Hormone ◽  
Normal Thyroid ◽  
Releasing Hormone ◽  
Trh Stimulation ◽  
Significant Difference ◽  
Bovine Tsh

ABSTRACT Thyrotrophin releasing hormone (TRH) stimulation test with 200 μg iv was performed in 35 patients with atoxic sporadic goitre. In 23 patients with diffuse goitre 7 showed a lack of increase in serum thyrotrophin (TSH) at a significantly increased frequency compared to controls (P = 0.0028). In 4 patients with solitary nodules 2 showed no significant response to TRH (negative), while 3 of the 8 patients with multinodular goitres had negative TRH test. Only 6 of the 12 TRH negative patients also had non-suppressible 131I uptake following T3. No significant difference in age and thyroid parameters was found between the TRH negative and TRH positive patients. In 7 TRH negative patients the test was repeated with 400 μg TRH but all remained negative. Five of these patients were given TRH perorally 80 mg daily for 2 weeks resulting in a significant increase in serum T4 and T3. No detectable increase in TSH was found. The response to iv bovine TSH in 4 TRH negative patients was found to be normal, suggesting that there was normal thyroid sensitivity to TSH. Our findings suggest that patients with TRH negative atoxic goitre can release biological active TSH following prolonged TRH stimulation. The high frequency of a negative standard TRH test in atoxic goitre seems to diminish the diagnostic value of the standard TRH test.

A Double-Blind Trial of Intravenous Thyrotrophin-Releasing Hormone in the Treatment of Reactive Depression

1975 ◽  
Vol 127 (3) ◽  
pp. 227-230 ◽  
Author(s):  
L. E. J. Evans ◽  
P. Hunter ◽  
R. Hall ◽  
Moira Johnston ◽  
V. Mathew Roy
Keyword(s):  
Double Blind Trial ◽  
Double Blind ◽  
Thyrotrophin Releasing Hormone ◽  
Releasing Hormone ◽  
Blind Trial ◽  
Reactive Depression ◽  
Antidepressant Effects ◽  
Significant Difference

SummaryIn a double-blind trial 600μg. of thyrotrophin-releasing hormone (TRH) was compared with placebo given daily for four days to two groups of ten patients. There was no significant difference between the antidepressant effects of TRH and placebo.

The effect of thyrotrophin-releasing hormone (TRH) on pancreatic hormone secretion in normal subjects

1983 ◽  
Vol 102 (2) ◽  
pp. 224-230 ◽  
Author(s):  
L. Ø. Dolva ◽  
K. F. Hanssen ◽  
O. Flaten ◽  
L. E. Hanssen ◽  
H. von Schenck
Keyword(s):  
Pancreatic Islet ◽  
Pancreatic Polypeptide ◽  
Plasma Levels ◽  
Hormone Secretion ◽  
Normal Subjects ◽  
Experimental Conditions ◽  
Arginine Infusion ◽  
Thyrotrophin Releasing Hormone ◽  
Releasing Hormone ◽  
Glucose Clamp Technique

Abstract. Thyrotrophin-releasing hormone (TRH) is present in the pancreas, mainly in the islets of Langerhans. We studied the effect of iv infused TRH on the plasma levels of pancreatic islet hormones in man, under different experimental conditions: 1) Arginine infusion. 2) Insulin induced hypoglycaemia. 3) Glucose clamp technique (maintainance of normoglycaemia by glucose infusion during insulin infusion). 4) TRH injection. Except for a minor inhibition of glucagon and pancreatic polypeptide following hypoglycaemic stimulation in one study, TRH had no significant effect on basal, stimulated or inhibited plasma glucagon, on insulin, somatostatin, pancreatic polypeptide or blood glucose. It is concluded that iv administration of TRH does not produce significant changes in peripheral plasma levels of pancreatic hormones. Application of techniques, which allow studies closer to the pancreatic islet, is probably necessary to assess the role of TRH in the regulation of endocrine pancreas.

The thyrotrophin-releasing hormone (TRH)-like peptides in rat prostate are not formed by expression of the TRH gene but are suppressed by thyroid hormone

1992 ◽  
Vol 132 (2) ◽  
pp. 177-184 ◽  
Author(s):  
R. Bilek ◽  
P. J. Gkonos ◽  
M. A. Tavianini ◽  
D. G. Smyth ◽  
B. A. Roos
Keyword(s):  
High Performance ◽  
Polymerase Chain Reaction Amplification ◽  
Exchange Chromatography ◽  
Adult Rats ◽  
Thyrotrophin Releasing Hormone ◽  
Basic Group ◽  
Releasing Hormone ◽  
Significant Difference ◽  
Reaction Amplification ◽  
Rat Prostate

ABSTRACT Thyrotrophin-releasing hormone (TRH)-immunoreactive peptides were extracted from rat prostate and divided into two groups by mini-column cation exchange chromatography. The amounts of the peptides in each group were determined by radioimmunoassay with a TRH antiserum. The unretained peptides which lacked a basic group and the retained peptides which possessed a basic group were further purified by high-performance liquid chromatography. The unretained fraction was found to contain a series of TRH-immunoreactive peptides, one of which corresponded chromatographically to synthetic pGlu-Glu-Pro amide and another to pGlu-Phe-Pro amide. None of the TRH-immunoreactive peptides in either fraction exhibited the chromatographic behaviour of TRH. Additional evidence for the absence of TRH gene expression in the prostate was obtained by Northern blot analysis and by application of polymerase chain reaction amplification, which failed to reveal TRH mRNA. Furthermore the preproTRH-derived peptide, preproTRH(53–74), could not be detected by radioimmunoassay. The influence of thyroid status was investigated on the levels of the TRH-like peptides in the prostate. Adult rats were treated chronically with thyroxine (T4) or propylthiouracil (PTU) and the concentrations of the TRH-immunoreactive peptides were determined by chromatography and radioimmunoassay. Treatment with T4 caused the levels of the neutral and acidic TRH-like peptides to fall to approximately one-third of the levels in the controls. No significant difference from the controls was seen in the concentrations of the peptides in the prostates of rats rendered hypothyroid by administration of PTU. The results demonstrate that rat prostate contains TRH-immunoreactive peptides which are not derived from the TRH gene. It is concluded that the TRH-like peptides arise from one or more genes which are structurally distinct from that which codes for the TRH preprohormone. Since these peptides are amidated and their levels are sensitive to hormone administration, it is likely that they fulfil a biological function. Journal of Endocrinology (1992) 132, 177–184

SERUM THYROTROPHIN AND THE RESPONSE TO THYROTROPHIN RELEASING HORMONE IN SYMPTOMLESS AUTOIMMUNE THYROIDITIS AND IN BORDERLINE AND OVERT HYPOTHYROIDISM

1974 ◽  
Vol 75 (2) ◽  
pp. 274-285 ◽  
Author(s):  
A. Gordin ◽  
P. Saarinen ◽  
R. Pelkonen ◽  
B.-A. Lamberg
Keyword(s):  
Autoimmune Thyroiditis ◽  
Elevated Serum ◽  
Mean Value ◽  
Primary Hypothyroidism ◽  
Overt Hypothyroidism ◽  
Thyrotrophin Releasing Hormone ◽  
Releasing Hormone ◽  
The Mean ◽  
The Individual ◽  
Serum Tsh

ABSTRACT Serum thyrotrophin (TSH) was determined by the double-antibody radioimmunoassay in 58 patients with primary hypothyroidism and was found to be elevated in all but 2 patients, one of whom had overt and one clinically borderline hypothyroidism. Six (29%) out of 21 subjects with symptomless autoimmune thyroiditis (SAT) had an elevated serum TSH level. There was little correlation between the severity of the disease and the serum TSH values in individual cases. However, the mean serum TSH value in overt hypothyroidism (93.4 μU/ml) was significantly higher than the mean value both in clinically borderline hypothyroidism (34.4 μU/ml) and in SAT (8.8 μU/ml). The response to the thyrotrophin-releasing hormone (TRH) was increased in all 39 patients with overt or borderline hypothyroidism and in 9 (43 %) of the 21 subjects with SAT. The individual TRH response in these two groups showed a marked overlap, but the mean response was significantly higher in overt (149.5 μU/ml) or clinically borderline hypothyroidism (99.9 μU/ml) than in SAT (35.3 μU/ml). Thus a normal basal TSH level in connection with a normal response to TRH excludes primary hypothyroidism, but nevertheless not all patients with elevated TSH values or increased responses to TRH are clinically hypothyroid.

DIE WIRKUNG VON SYNTHETISCHEM THYROTROPHIN RELEASING HORMONE AUF DIE ENTWICKLUNG EINES EXPERIMENTELLEN EXOPHTHALMUS BEIM GOLDFISCH

1971 ◽  
Vol 68 (2) ◽  
pp. 363-366 ◽  
Author(s):  
W. Wildmeister ◽  
F. A. Horster
Keyword(s):  
Carassius Auratus ◽  
Thyrotrophin Releasing Hormone ◽  
Releasing Hormone

ABSTRACT Gold-fishes (carassius auratus) were injected with synthetic thyrotrophin releasing hormone (TRH) in concentrations of 25 μg to 1000 μg/fish. TRH did not provoke endocrine exophthalmos.

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