Melatonin increases the ratio of 5-hydroxyindoleacetic acid to serotonin in the hypothalamus and brainstem concurrently with gonadal involution in male Syrian hamsters

1991 ◽  
Vol 69 (4) ◽  
pp. 1004-1009 ◽  
Author(s):  
J. Vriend
Keyword(s):  
Luteinizing Hormone ◽  
Thyroid Hormones ◽  
Serum Levels ◽  
Mediobasal Hypothalamus ◽  
Serotonergic Neurons ◽  
Catecholamine Synthesis ◽  
Syrian Hamsters ◽  
Catecholamine Turnover ◽  
Hydroxyindoleacetic Acid

Gonadal involution, with reduced serum levels of luteinizing hormone and prolactin, was induced in male Syrian hamsters by daily injections of melatonin, given in the evening. Highly significant increases in daytime concentrations of 5-hydroxyindoleacetic acid (5-HIAA) and in the ratio of 5-HIAA to serotonin (5-HT) were noted in extracts of mediobasal hypothalamus of melatonin-treated hamsters. An increase in the 5-HIAA/5-HT ratio, with decreased 5-HT concentrations, was found in brainstem extracts of hamsters treated with melatonin. The increase in the 5-HIAA/5-HT ratio was not prevented by inhibition of catecholamine synthesis with α-methyl-p-tyrosine, which suggests that the melatonin-induced increase in the 5-HIAA/5-HT ratio was not due to changes in catecholamine turnover. These results are consistent with the view that serotonergic neurons terminating in the hypothalamus mediate the melatonin-induced inhibition of luteinizing hormone, prolactin, and thyroid hormones accompanying gonadal involution.

Effects of Injections and/or Chronic Implants of Melatonin and 5-Methoxytryptamine on Plasma Thyroid Hormones in Male and Female Syrian Hamsters

1984 ◽  
Vol 39 (4) ◽  
pp. 361-366 ◽  
Author(s):  
Mary K. Vaughan ◽  
Bruce A. Richardson ◽  
Larry J. Petterborg ◽  
Anke P. Holtorf ◽  
George M. Vaughan ◽  
...  
Keyword(s):  
Thyroid Hormones ◽  
Male And Female ◽  
Syrian Hamsters

The effect of levothyroxine in comparison with placebo on serum osteocalcin levels in patients with subclinical hypothyroidism

2021 ◽  
Vol 16 ◽  
Author(s):  
Reihaneh Rezaee ◽  
Masoud Mohebbi ◽  
Mozhgan Afkhamizadeh ◽  
Mohammad Ali Yaghoubi ◽  
Mona Najaf Najafi ◽  
...  
Keyword(s):  
Thyroid Hormones ◽  
Subclinical Hypothyroidism ◽  
Intervention Group ◽  
Serum Levels ◽  
Overt Hypothyroidism ◽  
Serum Osteocalcin ◽  
Significant Difference ◽  
Before And After ◽  
Metabolic Conditions ◽  
And Control

Background and Objective: Subclinical hypothyroidism can potentially develop to overt hypothyroidism. Thyroid hormones have substantial roles in metabolism and glucose homeostasis and thus are closely related to determinant factors of metabolic syndromes, such as obesity and insulin resistance. Osteocalcin is considered a predictor of metabolic conditions in thyroid diseases. This study aimed to investigate the effect of levothyroxine vs. placebo on serum osteocalcin levels in patients with subclinical hypothyroidism. Methods: This randomized clinical trial was performed on 30 patients with subclinical hypothyroidism who were referred to the endocrine clinics of Ghaem and Imam Reza hospitals in Mashhad, Iran. After giving informed consent, patients were randomly divided into intervention (50 µg/day levothyroxine for 2 months) and control (placebo) groups. Serum levels of osteocalcin, thyroid hormones, lipid profile, insulin, and fasting glucose, as well as other clinical and anthropometric data, were measured at baseline and at the end of the study. SPSS was used to analyze the data and P<0.05 was considered significant. Results: Mean age in the intervention and control groups was 35.07 ± 9.94 and 31.30 ± 4.30, respectively (P=0.20). There was no significant difference between osteocalcin levels before and after the intervention in either of the groups (P=0.54). TSH level was significantly decreased in the levothyroxine group after the intervention (P<0.01). T4 level was significantly increased in the intervention group (P=0.02). Conclusion: Levothyroxine had no significant effect on increasing the levels of serum osteocalcin in patients with subclinical hypothyroidism. We have registered the trial in the Iranian registry of clinical trials (IRCT) with the registration code IRCT20171129037677N1.

Effects of domoic acid on serum levels of TSH and thyroid hormones

1995 ◽  
Vol 21 (3) ◽  
pp. 671-680 ◽  
Author(s):  
M. C. Arufe ◽  
B. Arias ◽  
R. Durán ◽  
M. Alfonso
Keyword(s):  
Thyroid Hormones ◽  
Domoic Acid ◽  
Serum Levels

Thyroid Stimulating Immunoglobulins: Measurement and Clinical use

1985 ◽  
Vol 69 (2) ◽  
pp. 113-121 ◽  
Author(s):  
C. A. Ollis ◽  
S. Tomlinson ◽  
D. S. Munro
Keyword(s):  
Thyroid Hormones ◽  
Elevated Serum ◽  
Serum Levels ◽  
The Other ◽  
Graves Disease ◽  
Clinical Use ◽  
Hormone Production ◽  
Skin Changes ◽  
Thyroid Stimulating Immunoglobulins ◽  
Eye Involvement

Graves’ disease is the commonest form of hyperthyroidism in which excessive production of thyroid hormones by the hyperplastic overactive thyroid gland produces elevated serum levels of the thyroid hormones tri-iodothyronine (T3) and thyroxine (T4). Many of the manifestations of Graves’ disease, increased basal metabolic rate, increased heart rate, heat intolerance, sweating and nervousness, can be attributed to the peripheral actions of the excess thyroid hormones. The pathogenesis of many of the other dramatic features of Graves’ disease, such as the eye involvement or localized skin changes, is not fully understood, but circulating immunoglobulins with thyroid stimulating activity are almost certainly linked to excess thyroid hormone production and thereby cause the hyperthyroidism.

scholarly journals Photoperiodic regulation of glutamatergic stimulation of secretion of luteinizing hormone in male Syrian hamsters

Reproduction ◽  
1992 ◽  
Vol 95 (3) ◽  
pp. 935-946 ◽  
Author(s):  
Y. Hui ◽  
M. H. Hastings ◽  
E. S. Maywood ◽  
F. J. P. Ebling
Keyword(s):  
Luteinizing Hormone ◽  
Syrian Hamsters ◽  
Photoperiodic Regulation ◽  
Stimulation Of

CHANGES IN SERUM LEVELS OF FOLLICLE STIMULATING HORMONE AND LUTEINIZING HORMONE SHORTLY BEFORE AND AFTER PARTURITION IN RATS

1974 ◽  
Vol 75 (3) ◽  
pp. 491-496 ◽  
Author(s):  
Junichi Mori ◽  
Hiroshi Nagasawa ◽  
Reiko Yanai ◽  
Junji Masaki
Keyword(s):  
Luteinizing Hormone ◽  
Follicle Stimulating Hormone ◽  
Serum Levels ◽  
Sprague Dawley ◽  
Appreciable Change ◽  
Serum Lh ◽  
Sprague Dawley Rats ◽  
Before And After ◽  
Average Serum ◽  
Stimulating Hormone

ABSTRACT The sequence of changes in the serum levels of follicle stimulating hormone (FSH) and luteinizing hormone (LH) from 2 days before to 24 h after parturition of primiparous Sprague-Dawley rats was investigated by radioimmunoassay. No appreciable change in average serum FSH levels was observed during 2 days before and 1 h after parturition. After this the levels increased gradually to show a peak at 7 h after parturition and then declined gradually until 24 h after parturition. However, the level at 24 h after parturition was still twice as high as that at parturition (0 h). The average serum LH levels which were low between 2 days before and 1 h after parturition, showed a peak at 7 h and decreased toward 13 h after parturition. The same levels as at parturition were maintained between 13 and 24 h after parturition. The time of surge of either FSH or LH was closely related to the time after parturition. There were some differences between FSH and LH in the patterns of sequence of changes in the serum levels near parturition.

Effects of small doses of bovine TSH on serum levels of free and total thyroid hormones, their degradation products, and diiodotyrosine

1985 ◽  
Vol 108 (2) ◽  
pp. 211-216 ◽  
Author(s):  
G. Benker ◽  
C. Splittstößer ◽  
H. Meinhold ◽  
Th. Olbricht ◽  
D. Reinwein
Keyword(s):  
Thyroid Hormones ◽  
Degradation Products ◽  
Thyroid Volume ◽  
Serum Levels ◽  
Direct Stimulation ◽  
Absolute Increase ◽  
Free Thyroid Hormones ◽  
Measurable Parameter ◽  
Small Doses ◽  
Bovine Tsh

Abstract. Bovine TSH was administered iv to 10 normal volunteers in doses of 2.5, 7.5, 15 and 30 mU/kg. Brisk elevations of serum diiodotyrosine occurred already after the smallest dose (mean, + 183%) while larger doses had only slight additional effects. T3 rose much higher than T4 (+71% compared to +23% after 15 mU bTSH/kg), and free thyroid hormones exhibited changes similar to total T3 and total T4. The mean absolute increase in serum fT3 ranged from 2.03 to 9.04 pmol/l and proved to be an easily measurable parameter for the TSH effect. Dose-response effects were seen for the increases of fT4, fT3 and T3. TBG and rT3 did not change but the degradation product 3,3'-T2 showed large increments of serum levels. There was no correlation between the response of T3 and T4, fT3 and fT4, or diiodotyrosine and any of the other parameters of thyroid function. The interindividual differences in the magnitude of thyroid hormone response to TSH were considerable, and there was no relationship between this response and thyroid volume by ultrasound. We conclude that direct stimulation of the thyroid gland with bTSH in small doses leads to consistent increases of thyroid hormones, especially T3 and fT3, that the response varies between individuals, and that the precursor diiodotyrosine is released together with thyroid hormones.

scholarly journals Synthesis and Metabolism of Thyroid Hormones Is Preferentially Maintained in Selenium-Deficient Transgenic Mice

Endocrinology ◽  
2006 ◽  
Vol 147 (3) ◽  
pp. 1306-1313 ◽  
Author(s):  
Lutz Schomburg ◽  
Cornelia Riese ◽  
Marten Michaelis ◽  
Emine Griebert ◽  
Marc O. Klein ◽  
...  
Keyword(s):  
Thyroid Gland ◽  
Thyroid Hormones ◽  
Knockout Mice ◽  
Serum Levels ◽  
Mrna Levels ◽  
Normal Range ◽  
Growth Defects ◽  
Low Levels

The thyroid gland is rich in selenium (Se) and expresses a variety of selenoproteins that are involved in antioxidative defense and metabolism of thyroid hormones (TH). Se deficiency impairs regular synthesis of selenoproteins and adequate TH metabolism. We recently generated mice that lack the plasma Se carrier, selenoprotein P (SePP). SePP-knockout mice display decreased serum Se levels and manifest growth defects and neurological abnormalities partly reminiscent of thyroid gland dysfunction or profound hypothyroidism. Thus, we probed the TH axis in developing and adult SePP-knockout mice. Surprisingly, expression of Se-dependent 5′-deiodinase type 1 was only slightly altered in liver, kidney, or thyroid at postnatal d 60, and 5′-deiodinase type 2 activity in brain was normal in SePP-knockout mice. Thyroid gland morphology, thyroid glutathione peroxidase activity, thyroid Se concentration, and serum levels of TSH, T4, or T3 were within normal range. Pituitary TSHβ transcripts and hepatic 5′-deiodinase type 1 mRNA levels were unchanged, indicating regular T3 bioactivity in thyrotropes and hepatocytes. Cerebellar granule cell migration as a sensitive indicator of local T3 action during development was undisturbed. Collectively, these findings demonstrate that low levels of serum Se or SePP in the absence of other challenges do not necessarily interfere with regular functioning of the TH axis. 5′-deiodinase isozymes are preferentially supplied, and Se-dependent enzymes in the thyroid are even less-dependent on serum levels of Se or SePP than in brain. This indicates a top priority of the thyroid gland and its selenoenzymes with respect to the hierarchical Se supply within the organism.

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