THE EFFECT OF TRIIODOTHYRONINE AND THYROXINE ON THYROTROPHIN LEVELS IN THE ANTERIOR PITUITARY GLAND AND BLOOD SERUM OF THYROIDECTOMIZED RATS

1966 ◽  
Vol 51 (4) ◽  
pp. 619-624 ◽  
Author(s):  
G. P. van Rees
Keyword(s):  
Thyroid Hormone ◽  
Pituitary Gland ◽  
Blood Serum ◽  
Anterior Pituitary ◽  
Serum Levels ◽  
Pituitary Glands ◽  
Higher Doses ◽  
Serum Tsh ◽  
Tsh Levels ◽  
Intact Rats

ABSTRACT Levels of thyrotrophin were determined in the anterior pituitary glands and blood sera of thyroidectomized rats after treatment with triiodothyronine or thyroxine for two weeks. The effects of increasing doses of both hormones on pituitary TSH levels appeared to be of a biphasic nature: whereas lower doses caused an increase, higher doses did so to a smaller extent or even caused a decrease, while at the same time progressively depressing the serum TSH levels. The highest pituitary levels found in thyroid hormone treated thyroidectomized rats were similar to those found in untreated intact rats, and equal doses of thyroid hormone were necessary to normalize the increased serum levels as well as the decreased pituitary contents in thyroidectomized animals. These findings are interpreted as indicating that in thyroidectomized rats the rate of release of TSH is depressed by lower doses of triiodothyronine and thyroxine than the rate of synthesis. Triiodothyronine was about three times more active than thyroxine.

Posttranscriptional regulation of rat growth hormone gene expression: increased message stability and nuclear polyadenylation accompany thyroid hormone depletion

1992 ◽  
Vol 12 (6) ◽  
pp. 2624-2632
Author(s):  
D Murphy ◽  
K Pardy ◽  
V Seah ◽  
D Carter
Keyword(s):  
Growth Hormone ◽  
Thyroid Hormone ◽  
Pituitary Gland ◽  
Anterior Pituitary ◽  
Posttranscriptional Regulation ◽  
Anterior Pituitary Gland ◽  
Growth Hormone Gene ◽  
Gh Gene ◽  
Rat Growth ◽  
Pituitary Glands

In thyroid hormone-depleted rats, the rate of transcription of the growth hormone (GH) gene in the anterior pituitary gland is lower than the rate in euthyroid controls, and there is a corresponding reduction in the abundance of the GH mRNA. Concomitantly, the poly(A) tail of the GH mRNA increases in length. Examination of nuclear RNA from anterior pituitary glands of control and thyroid hormone-depleted rats revealed no difference in the length of pre-mRNAs containing the first and last introns of the GH gene. However, mature nuclear GH RNA is differentially polyadenylated in euthyroid and hypothyroid animals. We suggest that the extent of polyadenylation of the GH transcript is regulated in the cell nucleus concomitant with or subsequent to the splicing of the pre-mRNA. Experiments with anterior pituitary gland explant cultures demonstrated that the GH mRNA from thyroid hormone-depleted rats is more stable than its euthyroid counterpart and that the poly(A) tail may contribute to the differential stability of free GH ribonucleoproteins.

Relationships among release of prolactin, synthesis of DNA and growth of the anterior pituitary gland of the rat: effects of oestrogen and sulpiride

1982 ◽  
Vol 94 (1) ◽  
pp. 1-10 ◽  
Author(s):  
G. A. Jahn ◽  
G. A. Machiavelli ◽  
L. E. Kalbermann ◽  
I. Szijan ◽  
G. E. Alonso ◽  
...  
Keyword(s):  
Pituitary Gland ◽  
Anterior Pituitary ◽  
Single Injection ◽  
Serum Levels ◽  
Anterior Pituitary Gland ◽  
Male Rats ◽  
Maximum Increase ◽  
End Of Treatment ◽  
Pituitary Glands ◽  
Prolactin Synthesis

The effect of daily injections of sulpiride was compared with that of a single injection of the drug in male rats which had been treated with oestradiol diundecenoate for various periods of time. We studied the effect of the different treatments on weight of the pituitary gland, concentration of prolactin and incorporation of [3H]thymidine into DNA in the pituitary gland and on serum levels of prolactin. Administration of the oestrogen produced a marked increase in the synthesis of DNA at day 7. The stimulation diminished at day 21 and was not significant at day 45. The maximum increase in the concentration of prolactin in serum and pituitary glands was observed during the first 7 days (approximately 400 and 150% respectively) and in the weight of the anterior pituitary gland after 21 days of treatment (approximately 107%). A single injection of sulpiride markedly stimulated the release of prolactin and the synthesis of DNA at day 7. Both these effects diminished at day 21 and disappeared by day 45. Daily injections of sulpiride also produced similar changes in the release of prolactin and in the replication of DNA. The growth of the anterior pituitary gland was greater in this group than in the rats which had been treated with oestradiol diundecenoate only. After the end of treatment with oestrogen and sulpiride the pituitary weight and the concentration of prolactin in the anterior pituitary gland diminished together with levels of prolactin and oestrogen in serum. There was a good correlation between weight of the gland and serum levels of prolactin. The results further support the idea of a mechanism which controls the proliferation of lactotrophs in which the release of the hormone is accompanied by an increase in pituitary DNA synthesis.

scholarly journals Posttranscriptional regulation of rat growth hormone gene expression: increased message stability and nuclear polyadenylation accompany thyroid hormone depletion.

1992 ◽  
Vol 12 (6) ◽  
pp. 2624-2632 ◽  
Author(s):  
D Murphy ◽  
K Pardy ◽  
V Seah ◽  
D Carter
Keyword(s):  
Growth Hormone ◽  
Thyroid Hormone ◽  
Pituitary Gland ◽  
Anterior Pituitary ◽  
Posttranscriptional Regulation ◽  
Anterior Pituitary Gland ◽  
Growth Hormone Gene ◽  
Gh Gene ◽  
Rat Growth ◽  
Pituitary Glands

In thyroid hormone-depleted rats, the rate of transcription of the growth hormone (GH) gene in the anterior pituitary gland is lower than the rate in euthyroid controls, and there is a corresponding reduction in the abundance of the GH mRNA. Concomitantly, the poly(A) tail of the GH mRNA increases in length. Examination of nuclear RNA from anterior pituitary glands of control and thyroid hormone-depleted rats revealed no difference in the length of pre-mRNAs containing the first and last introns of the GH gene. However, mature nuclear GH RNA is differentially polyadenylated in euthyroid and hypothyroid animals. We suggest that the extent of polyadenylation of the GH transcript is regulated in the cell nucleus concomitant with or subsequent to the splicing of the pre-mRNA. Experiments with anterior pituitary gland explant cultures demonstrated that the GH mRNA from thyroid hormone-depleted rats is more stable than its euthyroid counterpart and that the poly(A) tail may contribute to the differential stability of free GH ribonucleoproteins.

THYROID HORMONE REGULATES VASOACTIVE INTESTINAL PEPTIDE (VIP) mRNA LEVELS IN THE RAT ANTERIOR PITUITARY GLAND

Endocrinology ◽  
1989 ◽  
Vol 125 (4) ◽  
pp. 2221-2223 ◽  
Author(s):  
THOMAS P. SEGERSON ◽  
KAREN S.L. LAM ◽  
LUCINDA CACICEDO ◽  
NAOTO MINAMITANI ◽  
J. STEPHEN FINK ◽  
...  
Keyword(s):  
Thyroid Hormone ◽  
Pituitary Gland ◽  
Vasoactive Intestinal Peptide ◽  
Anterior Pituitary ◽  
Anterior Pituitary Gland ◽  
Mrna Levels

THE INFLUENCE OF METHALLIBURE (ICI 33,828) ON SERUM AND PITUITARY THYROID-STIMULATING HORMONE LEVELS IN THE RAT

1971 ◽  
Vol 49 (4) ◽  
pp. 569-572
Author(s):  
J. R. BOURKE ◽  
S. W. MANLEY ◽  
R. W. HAWKER
Keyword(s):  
Thyroid Stimulating Hormone ◽  
Feedback Mechanism ◽  
Seminal Vesicles ◽  
Endocrine Organs ◽  
System 1 ◽  
Dose Levels ◽  
Higher Doses ◽  
Serum Tsh ◽  
Tsh Levels ◽  
Stimulating Hormone

SUMMARY The effect of methallibure (ICI 33,828), a non-steroidal pituitary inhibitor, on serum and pituitary thyroid-stimulating hormone (TSH) levels has been investigated. A biphasic action of the drug on serum TSH levels was observed, the greatest falls occurring with the lowest doses (2mg/day). Increasing dose and period of administration induced progressive decreases in pituitary TSH content. These results are interpreted in terms of three actions on the thyroid—pituitary system: (1) inhibition of the release of TSH from the pituitary, (2) inhibition of TSH synthesis evident only at higher doses, and (3) a thyroid-blocking action, which is also only observed at the higher dose levels, with consequent pituitary stimulation via the thyroid—pituitary feedback mechanism. Effects upon body weight and weight of endocrine organs are reported, that upon the seminal vesicles being the most marked.

scholarly journals Gonadotrope Plasticity at Cellular and Population Levels

Endocrinology ◽  
2012 ◽  
Vol 153 (10) ◽  
pp. 4729-4739 ◽  
Author(s):  
Zahara Alim ◽  
Cheryl Hartshorn ◽  
Oliver Mai ◽  
Iain Stitt ◽  
Colin Clay ◽  
...  
Keyword(s):  
Pituitary Gland ◽  
Anterior Pituitary ◽  
Ex Vivo ◽  
Single Cells ◽  
Anterior Pituitary Gland ◽  
Female Mice ◽  
Model Animal ◽  
Pituitary Glands ◽  
Acute Changes

Abstract Hormone-secreting cells within the anterior pituitary gland may form organized and interdigitated networks that adapt to changing endocrine conditions in different physiological contexts. For gonadotropes, this might reflect a strategy to cope with acute changes throughout different female reproductive stages. The current study examined gonadotropes in female mice at characteristically different hormonal stages: prepubertal, postpubertal, and lactating. Gonadotrope plasticity was examined at the level of the whole population and single cells at different stages by imaging both fixed and live pituitary slices. The use of a model animal providing for the identification of selectively fluorescent gonadotropes allowed the particular advantage of defining cellular plasticity specifically for gonadotropes. In vivo analyses of gonadotropes relative to vasculature showed significantly different gonadotrope distributions across physiological states. Video microscopy studies using live slices ex vivo demonstrated pituitary cell plasticity in the form of movements and protrusions in response to GnRH. As positive feedback from rising estradiol levels is important for priming the anterior pituitary gland for the LH surge, experiments provide evidence of estradiol effects on GnRH signaling in gonadotropes. The experiments presented herein provide new insight into potential plasticity of gonadotropes within the anterior pituitary glands of female mice.

scholarly journals Nitric oxide sensitive-guanylyl cyclase subunit expression changes during estrous cycle in anterior pituitary glands

2009 ◽  
Vol 296 (4) ◽  
pp. E731-E737 ◽  
Author(s):  
Jimena P. Cabilla ◽  
Sonia A. Ronchetti ◽  
Silvana I. Nudler ◽  
Eliana A. Miler ◽  
Fernanda A. Quinteros ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Pituitary Gland ◽  
Estrous Cycle ◽  
Guanylyl Cyclase ◽  
Anterior Pituitary ◽  
Acute Treatment ◽  
Α Subunit ◽  
Immature Rats ◽  
Subunit Expression ◽  
Pituitary Glands

17β-Estradiol (E2) exerts inhibitory actions on the nitric oxide pathway in rat adult pituitary glands. Previously, we reported that in vivo E2 acute treatment had opposite effects on soluble guanylyl cyclase (sGC) subunits, increasing α1- and decreasing β1-subunit protein and mRNA expression and decreasing sGC activity in immature rats. Here we studied the E2 effect on sGC protein and mRNA expression in anterior pituitary gland from adult female rats to address whether the maturation of the hypothalamus-pituitary axis influences its effects and to corroborate whether these effects occur in physiological conditions such as during estrous cycle. E2 administration causes the same effect on sGC as seen in immature rats, and these effects are estrogen receptor dependent. These results suggest that E2 is the main effector of these changes. Since the sGC α-subunit increases while the sGC activity decreases, we studied if other less active isoforms of the sGC α-subunit are expressed. Here we show for the first time that sGCα2 and sGCα2 inhibitory (α2i) isoforms are expressed in this gland, but only sGCα2i mRNA increased after E2 acute treatment. Finally, to test whether E2 effects take place under a physiological condition, sGC subunit expression was monitored over estrous cycle. sGCα1, -β1, and -α2i fluctuate along estrous cycle, and these changes are directly related with E2 level fluctuations rather than to NO level variations. These findings show that E2 physiologically regulates sGC expression and highlight a novel mechanism by which E2 downregulates sGC activity in rat anterior pituitary gland.

scholarly journals Management of subclinical hypothyroidism in pregnancy: are we too simplistic?

2015 ◽  
Vol 173 (1) ◽  
pp. P1-P11 ◽  
Author(s):  
Georg Brabant ◽  
Robin P Peeters ◽  
Shiao Y Chan ◽  
Juan Bernal ◽  
Philippe Bouchard ◽  
...  
Keyword(s):  
Thyroid Hormone ◽  
Subclinical Hypothyroidism ◽  
Serum Levels ◽  
Clear Understanding ◽  
Specific Antibodies ◽  
Hormone Transport ◽  
Limited Experience ◽  
Pregnant State ◽  
Tsh Levels ◽  
In Pregnancy

Guideline advice of many societies on the management of subclinical hypothyroidism in pregnancy suggests treatment when TSH serum levels exceed 2.5 mU/l. Justification of this procedure is based on limited experience, mainly from studies carried out in patients with positive thyroid-specific antibodies and higher TSH levels that classically define the condition in the non-pregnant state. Taking into account a lack of clear understanding of the regulation of thyroid hormone transport through the utero-placental unit and in the absence of foetal markers to monitor the adequacy of thyroxine treatment, this review attempts to discuss currently available data and suggests a more cautious approach.

scholarly journals Diabetes and Hypercholesterolemia Impair the Cytological Structure of the Anterior Pituitary Gland

2019 ◽  
Vol 16 (3) ◽  
pp. 649-658
Author(s):  
Ahmed MR Abdo ◽  
Mohamed E El-Beeh ◽  
Sameer H. Qari ◽  
Dina A El-badry ◽  
Hassan IH El-Sayyad
Keyword(s):  
Body Weight ◽  
Pituitary Gland ◽  
Anterior Pituitary ◽  
Secretory Granules ◽  
Reproductive Function ◽  
Anterior Lobe ◽  
Anterior Pituitary Gland ◽  
Albino Rats ◽  
Pituitary Glands ◽  
Cytological Picture

Increase consumption of high fat diet was found to alter blood sugar level similar to diabetes and contributed to the development of obesity and affected the reproductive function of both sexes. The study aimed to clarify the influence of diabetes and or hypercholesterolemia on the cytological picture of cells of the anterior lobe of pituitary gland of male albino rats. Eighteen male albino rats weighing approximately 120 gram body weight were divided into three main groups; control, diabetes, hypercholesterolemia, diabetes (single i.p. 40 mg streptozotocin/kg B.wt plus 100mg. nicotinamide /kg body weight) and hypercholesterolemia (diet containing 3% cholesterol). Dietary feeding on cholesterol and diabetes were carried out for 12 weeks. At the end of treatment, animals were sacrificed, and pituitary glands were separated and their anterior lobe was processed for cytological investigations by transmission electron microscopy. The present study revealed that the rats subjected to experimental diabetes and/ or hypercholesterolemia exhibited a decrease of the secretory granules within the gonadotroph cells somatotroph and corticotrophin cells. There was a detected intracellular accumulation of fat globules in both the gonado- and sommatotroph cells. The authors reported that the altered cytological structures of the secretory function of the anterior pituitary gland led to marked impairment of the male hormonal level and causing infertility.

scholarly journals A rare mutation of thyroid hormone receptor beta gene in thyroid hormone resistance syndrome

2021 ◽  
Vol 2021 ◽  
Author(s):  
Michela Del Prete ◽  
Fabrizio Muratori ◽  
Irene Campi ◽  
Gianleone Di Sacco ◽  
Federico Vignati ◽  
...  
Keyword(s):  
Thyroid Hormone ◽  
Thyroid Hormones ◽  
Genetic Test ◽  
List Type ◽  
Thyroid Function Tests ◽  
Resistance To Thyroid Hormone ◽  
Hereditary Syndrome ◽  
Serum Tsh ◽  
Receptor Beta ◽  
Tsh Levels

Summary Resistance to thyroid hormone (RTH) is a rare hereditary syndrome with impaired sensitivity to thyroid hormones (TH) and reduced intracellular action of triiodothyronine (T3) caused by genetic variants of TH receptor beta (TRB) or alpha (TRA). RTH type beta (RTHβ) due to dominant negative variants in the TRB gene usually occurs with persistent elevation of circulating free TH, non-suppressed serum TSH levels responding to a thyrotropin-releasing hormone (TRH) test, an absence of typical symptoms of hyperthyroidism and goiter. Here, we present a rare variant in the TRB gene reported for the first time in an Italian patient with generalized RTHβ syndrome. The patient showed elevated TH, with non-suppressed TSH levels and underwent thyroid surgery two different times for multinodular goiter. The genetic test showed a heterozygous mutation in exon 9 of the TRB gene resulting in the replacement of threonine (ACG) with methionine (ATG) at codon 310 (p.M310T). RTHβ syndrome should be considered in patients with elevated TH, non-suppressed TSH levels and goiter. Learning points Resistance to thyroid hormone (RTH) is a rare autosomal dominant hereditary syndrome with impaired tissue responsiveness to thyroid hormones (TH). Diagnosis of RTH is usually based on the clinical finding of discrepant thyroid function tests and confirmed by a genetic test. RTH is a rare condition that must be considered for the management of patients with goiter, elevation of TH and non-suppressed serum TSH levels in order to avoid unnecessary treatments.

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