Thyroid hormone modulation of the hypothalamic growth hormone (GH)-releasing factor-pituitary GH axis in the rat.

Miki, Nobuhiro; Ono, Masami; Hizuka, Naomi; Aoki, Tomoko; Demura, Hiroshi

doi:10.1172/jci115823

Cited by 23 publications

(13 citation statements)

References 60 publications

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“…The secretion of m G R F in response to 50 mM K + was highly constant with mean (+SE) values ranging from 13.2iO.2 to 16.2+2.1 pg/hypothalamus/30 min in 6 experiments, each using 10-12 animals. This value is only one third of the GRFreleasing capacity of the rat hypothalamus, which we observed previously by identical experimental methods (36). No definite answer is available as to what determines the species difference in the releasing capacity of G R F between the two species.…”

Section: Discussionmentioning

confidence: 53%

“…We previously reported the hypothalamic content and in vitro secretion of G R F in the rat (35,36). It would be interesting to refer to the species difference in these parameters on GRF between rat and mouse.…”

Section: Discussionmentioning

confidence: 99%

“…Secretion experiments were carried out exactly by the same method as that previously used for in vitro incubation of the rat hypothalamus (36). Four hypothalamic fragments obtained from two mice were incubated in one plastic vial.…”

Section: Secretion Experiments and Characterization Of Secreted Farm mentioning

confidence: 99%

“…The method was exactly the same as that used for in vitro incubation experiments of rat hypothalamic fragments (35,36). except for the mechanical interruption of the pituitary stalk because of technical difficulty in cutting it with a pair of scissors.…”

Section: Hi;poihafamic Incuharionmentioning

confidence: 99%

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Characterization and Localization of Mouse Hypothalamic Growth Hormone‐Releasing Factor and Effect of Gold Thioglucose‐Induced Hypothalamic Lesions

Miki¹,

Ono²,

Asakawa-Yasumoto³

et al. 1994

J Neuroendocrinology

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Hypothalamic growth hormone-releasing factor (GRF) in higher mammals, including human GRF, is a 44 amino acid residue peptide and is highly homologous in structure. By contrast, mouse GRF (mGRF) recently deduced by cDNA cloning consists of only 42 residues and shows relatively low homology to the GRFs of higher mammals and the same rodent species, rat. To characterize and localize the predicted mature mGRF peptide in the hypothalamus, we have generated its antiserum and developed a homologous radioimmunoassay. lmmunoreactive mGRF in the acid hypothalamic extract was eluted as a single peak at a position identical to that of synthetic peptide on both gel filtration chromatography and reverse-phase high-performance liquid chromatography (HPLC). Secretion of immunoreactive mGRF from incubated hypothalami increased several fold in response to 50 mM K' , and this rise was abolished in the absence of medium Ca'+. Only a single peak of irnmunoreactive mGRF that coeluted with synthetic replicate was observed after the K+-stimulated medium was extracted on Bond Elut C18 cartridges and applied on reverse-phase HPLC. lmmunohistochemistry identified many mGRF-positive cell bodies in the arcuate nucleus and dense bundles of immunoreactive fibers in the median eminence. Treatment of mice with gold thioglucose (GTG), a chemical agent known to cause hypothalamic lesions, markedly depleted both content and in vitro secretion of immunoreactive mGRF. The decline in mGRF secretion was greater in GTG obese than in nonobese mice, whereas somatostatin secretion was not affected by GTG treatment. AS compared to the previous findings obtained on rat GRF, mouse had approximately the same content of hypothalamic GRF, but retained only one third the capacity to release GRF in response to the same depolarizing stimulus.These findings demonstrate that mouse hypothalamus contains and secretes a mGRF-like molecule which has immunological and chromatographic characteristics identical to that predicted by molecular cloning. The depolarization-evoked, Ca' ' -dependent release of immunoreactive mGRF and its neuronal localization in the arcuate nucleus-median eminence region indicate that it functions as a hypophysiotropic hormone of physiological importance. GTG produces hypothalamic GRF deficiency, probably sparing hypophysiotropic somatostatin neurons, and could be used to generate a mouse model for human GRF-deficient dwarfism.

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Section: Discussionmentioning

confidence: 53%

Section: Discussionmentioning

confidence: 99%

Section: Secretion Experiments and Characterization Of Secreted Farm mentioning

confidence: 99%

Section: Hi;poihafamic Incuharionmentioning

confidence: 99%

See 2 more Smart Citations

Characterization and Localization of Mouse Hypothalamic Growth Hormone‐Releasing Factor and Effect of Gold Thioglucose‐Induced Hypothalamic Lesions

Miki¹,

Ono²,

Asakawa-Yasumoto³

et al. 1994

J Neuroendocrinology

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“…The intensity of GRF receptor mRNA was normalized by that of f3-actin mRNA. Hypothalamic incubation was performed as described [6,7], using 12 male and 12 female rats in each of three separate experiments.…”

Section: Methodsmentioning

confidence: 99%

Gender Difference in Pituitary Growth Hormone-Releasing Factor (GRF) Receptor Gene Expression in the Rat.

Miki¹,

Ono²,

Murata³

et al. 1996

Endocr J

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Structural abnormalities underlying alveolar hypoventilation and fluid imbalance in the dystrophic hamster lung

et al. 1999

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Bio 14.6 dystrophic hamsters exhibit alveolar hypoventilation and increased lung hydration. This study evaluated whether age-and genotype-related morphometric differences in lungs exist and correlate with the development of lung pathophysiology. Morphometry was used to characterize lungs of young (Y) and mature (M) control (C) and dystrophic (D) hamsters. With age, both C and D had increased barrier surface area [S(a-b,p)] and morphometric diffusing capacity index [mdci], and decreased harmonic thickness. In C but not D, mean capillary diameter [d c ] and parenchymal volume density [V v (p,L)] increased with age, whereas barrier arithmetic thickness decreased. Chord length increased with age, whereas the ratio of parenchymal surface area to airspace volume [S/V] and the intersection density of the air-blood interface [I v (a-b,s)] decreased in D but not C. At both ages, lung volume relative to body mass was greater in D than C. With that exception, no genotype differences were found in young hamsters. Mature D displayed lower V v (p,L), S/V, d c , I v (a-b,s), S(a-b,p), and mdci than mature C. Independent of age, chord length was greater but arithmetic thickness, airspace surface density, frequency of type II cells, and lamellar body area and volume density were lower in D than C. We conclude: 1) lung volume relative to body growth was greater in dystrophics than controls; 2) parenchymal remodeling was delayed or abnormal in dystro-phics; 3) lower diffusing capacity in mature dystrophics may effect alveolar hypoventilation; 4) lower tissue volume, surface area, and the type II cell abnormalities in dystrophics could reduce sodium and water transport leading to greater lung hydration. Anat Rec 256:321-333, 1999. 1999 Wiley-Liss, Inc.

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Thyroid hormone modulation of the hypothalamic growth hormone (GH)-releasing factor-pituitary GH axis in the rat.

Cited by 23 publications

References 60 publications

Characterization and Localization of Mouse Hypothalamic Growth Hormone‐Releasing Factor and Effect of Gold Thioglucose‐Induced Hypothalamic Lesions

Characterization and Localization of Mouse Hypothalamic Growth Hormone‐Releasing Factor and Effect of Gold Thioglucose‐Induced Hypothalamic Lesions

Gender Difference in Pituitary Growth Hormone-Releasing Factor (GRF) Receptor Gene Expression in the Rat.

Structural abnormalities underlying alveolar hypoventilation and fluid imbalance in the dystrophic hamster lung

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