Differential response of neuropeptide Y, substance P and vasoactive intestinal polypeptide in the rat anterior pituitary gland to alterations in thyroid hormone status

1994 ◽  
Vol 143 (2) ◽  
pp. 393-397 ◽  
Author(s):  
P M Jones ◽  
M A Ghatei ◽  
S C Wallis ◽  
S R Bloom
Keyword(s):  
Thyroid Hormone ◽  
Substance P ◽  
Pituitary Gland ◽  
Neuropeptide Y ◽  
Negative Feedback ◽  
Vasoactive Intestinal Polypeptide ◽  
Anterior Pituitary ◽  
Mrna Levels ◽  
Hormone Status ◽  
Mrna Content

Abstract We have compared the effects of thyroidectomy with those of thyroxine (T4) replacement and excess T4 treatment on neuropeptide Y (NPY) in the rat anterior pituitary, and compared these with the effects on substance P (SP) and vasoactive intestinal peptide (VIP). Thyroidectomy produced large increases in the peptide content of NPY (335 ± 58 fmol/gland vs 15 ± 4 fmol/gland in controls), SP (581 ±90 vs 199 ±32 fmol/gland) and VIP (1386 ± 395 vs 417 ± 77 fmol/gland) together with large increases in the respective prohormone encoding mRNAs, NPY 21 760%±1290%, preprotachykinin-A (PPT-A; which encodes the substance P precursor) 1744%± 190% and VIP 680% ± 129%. Thyroidectomy together with T4 replacement produced an increase in both NPY peptide (426 ±72 vs 15 ±4 fmol/gland) and mRNA content 970%±156% of controls). The peptide contents of SP and VIP were not significantly different from controls. PPT-A and VIP mRNA levels were decreased relative to controls (31%±8% and 23%± 10% respectively). In intact animals treated with excess T4 (hyperthyroid animals), SP and VIP peptide contents were significantly reduced (55 ±13 vs 199±32 fmol/gland and 226 ± 24 vs 417± fmol/gland respectively) and the SP and VIP encoding mRNAs were also decreased (8% ±3% and 11%±4% respectively). In this group there was no detectable alteration in either the peptide or mRNA content of NPY. Thus, the response of pituitary NPY to thyroid hormone manipulations cannot be explained in terms of negative feedback physiology and is different from those of SP and VIP. The results suggest that the regulation of locally produced NPY in the rat anterior pituitary is complex and may be influenced by thyroidal factors in addition to T4. Journal of Endocrinology (1994) 143, 393–397

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 adrenal hormone status on neuroendocrine peptides in the rat anterior pituitary gland

1990 ◽  
Vol 127 (3) ◽  
pp. 437-NP ◽  
Author(s):  
P. M. Jones ◽  
D. J. O'Halloran ◽  
M. A. Ghatei ◽  
J. Domin ◽  
S. R. Bloom
Keyword(s):  
Pituitary Gland ◽  
Anterior Pituitary ◽  
Anterior Pituitary Gland ◽  
Male Rat ◽  
Mrna Levels ◽  
Adrenal Hormone ◽  
Rat Pituitary ◽  
Hormone Status ◽  
Anterior Pituitary Function ◽  
Wet Weight

ABSTRACT Neuropeptide Y (NPY), neurotensin (NT), substance P (SP) and vasoactive intestinal peptide (VIP) are four structurally unrelated neuroendocrine peptides which affect anterior pituitary function. All four peptides appear to be locally synthesized in the anterior pituitary gland and have been shown to be regulated by thyroid and/or sex hormone status. We show here that NT, SP and VIP but not NPY are influenced by adrenal hormone status in the male rat pituitary gland. Adrenalectomy increased the content of VIP (35·4±4·0 (s.e.m.) vs control 11·9±1·1 pmol/g wet weight) but decreased that of SP (18·8±2·3 vs control 36·7 ±3·9 pmol/g wet weight). Adrenalectomy combined with castration decreased the content of SP (14·6±3·5 vs control 36·7±3·9 pmol/g wet weight) but had no effect on VIP content. Treatment with dexamethasone produced significant decreases in NT, SP and VIP contents (17·8±2·3 vs control 32·6±3·4 pmol/g wet weight, 5·5±0·9 vs control 36·7±3·9 pmol/g wet weight and 4·2±0·6 vs control 11·9±1·1 pmol/g wet weight respectively). The changes in pituitary peptide contents occurred in parallel with changes in mRNA levels, suggesting that alterations in glucocorticoid hormone status can alter the synthesis of these peptides. These results, together with the known effects of these neuroendocrine peptides suggest possible functions for locally produced SP and VIP in regulating the secretion of adrenocorticotrophin and/or other proopiomelanocortin-derived peptides. The differential effects of adrenalectomy and adrenalectomy combined with castration on VIP suggests that the regulation of this pituitary peptide is complex, and may be dependent, in part at least, on gonadal factors. Journal of Endocrinology (1990) 127, 437–444

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.

scholarly journals IGF-I regulates pro-opiomelanocortin and GH gene expression in the mouse pituitary gland

2003 ◽  
Vol 178 (1) ◽  
pp. 71-82 ◽  
Author(s):  
J Honda ◽  
Y Manabe ◽  
R Matsumura ◽  
S Takeuchi ◽  
S Takahashi
Keyword(s):  
Pituitary Gland ◽  
Anterior Pituitary ◽  
Northern Blotting ◽  
Pituitary Cells ◽  
Mrna Levels ◽  
Gh Treatment ◽  
Gh Receptor ◽  
Pomc Mrna ◽  
Igf I ◽  
Mouse Pituitary

IGF-I is expressed in somatotrophs, and IGF-I receptors are expressed in most somatotrophs and some corticotrophs in the mouse pituitary gland. Our recent study demonstrated that IGF-I stimulates the proliferation of corticotrophs in the mouse pituitary. These results suggested that somatotrophs regulate corticotrophic functions as well as somatotrophic functions by the mediation of IGF-I molecules. The present study aimed to clarify factors regulating pituitary IGF-I expression and also the roles exerted by IGF-I within the mouse anterior pituitary gland. Mouse anterior pituitary cells were isolated and cultured under serum-free conditions. GH (0.5 or 1 microg/ml), ACTH (10(-8) or 10(-7) M), GH-releasing hormone (GHRH; 10(-8) or 10(-7) M), dexamethasone (DEX; 10(-8) or 10(-7) M) and estradiol-17beta (e2; 10(-11) or 10(-9) M) were given for 24 h. IGF-I mRNA levels were measured using competitive RT-PCR, and GH and pro-opiomelanocortin (POMC) mRNA levels were measured using Northern blotting analysis. GH treatment significantly increased IGF-I mRNA levels (1.5- or 2.1-fold). ACTH treatment did not alter GH and IGF-I mRNA levels. IGF-I treatment decreased GH mRNA levels (0.7- or 0.5-fold), but increased POMC mRNA levels (1.8-fold). GH treatment (4 or 8 microg/ml) for 4 days increased POMC mRNA levels. GHRH treatment increased GH mRNA levels (1.3-fold), but not IGF-I mRNA levels. DEX treatment significantly decreased IGF-I mRNA levels (0.8-fold). e2 treatment did not affect IGF-I mRNA levels. GH receptor mRNA, probably with GH-binding protein mRNA, was detected in somatotrophs, and some mammotrophs and gonadotrophs by in situ hybridization using GH receptor cDNA as a probe. These results suggested that IGF-I expression in somatotrophs is regulated by pituitary GH, and that IGF-I suppresses GH expression and stimulates POMC expression at the transcription level. Pituitary IGF-I produced in somatotrophs is probably involved in the regulation of somatotroph and corticotroph functions.

scholarly journals Ontogeny of pituitary thyrotrophs and regulation by endogenous thyroid hormone feedback in the chick embryo

2005 ◽  
Vol 184 (2) ◽  
pp. 407-416 ◽  
Author(s):  
Michael Muchow ◽  
Ioannis Bossis ◽  
Tom E Porter
Keyword(s):  
Thyroid Hormone ◽  
Thyroid Hormones ◽  
Anterior Pituitary ◽  
Feedback Regulation ◽  
Thyroid Stimulating Hormone ◽  
Mrna Levels ◽  
Hormone Production ◽  
Negative Feedback Regulation ◽  
Cephalic Lobe ◽  
Whole Mount

Increased thyroid hormone production is essential for hatching of the chick and for the increased metabolism necessary for posthatch endothermic life. However, little is known about the ontogeny and distribution of pituitary thyrotrophs during this period or whether pituitary thyroid-stimulating hormone (TSH) production is regulated by endogenous thyroid hormones during chick embryonic development. This study assessed the abundance and location of pituitary thyrotrophs and the regulation of TSHβ peptide and mRNA levels by endogenous thyroid hormones prior to hatching. TSHβ-containing cells were first detected on embryonic day (e) 11, and the thyrotroph population increased to maximum levels on e17 and e19 and then decreased prior to hatching (d1). Thyrotroph distribution within the cephalic lobe of the anterior pituitary was determined on e19 by whole-mount immunocytochemistry for TSHβ peptide and by whole-mount in situ hybridization for TSHβ mRNA. Thyrotroph distribution within the cephalic lobe was heterogeneous among embryos, but most commonly extended from the ventral medial region to the dorsal lateral regions, along the boundary of the cephalic and caudal lobes. Inhibition of endogenous thyroid hormone production with methi-mazole (MMI) decreased plasma thyroxine (T4) levels and increased pituitary TSHβ mRNA levels on e19 and d1. However, control pituitaries contained significantly more TSHβ peptide than MMI-treated pituitaries on e17 and e19, suggesting higher TSH secretion into the blood in MMI-treated groups. We conclude that thyrotroph abundance and TSH production increase prior to hatching, that thyrotrophs are localized heterogenenously within the cephalic lobe of the anterior pituitary at that time, and that TSH gene expression and secretion are under negative feedback regulation from thyroid hormones during this critical period of development.

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