The Somatomedin Hypothesis: 2001

Roith, Derek Le; Bondy, Carolyn A.; Yakar, Shoshana; Liu, Junli; Butler, Andrew A.

doi:10.1210/edrv.22.1.0419

Cited by 987 publications

(786 citation statements)

References 203 publications

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“…Many of the anabolic actions of GH are mediated by IGF-1 [11,57], which is predominantly synthesized and released in response to circulating GH levels [58].…”

Section: Hormonal Responsesmentioning

confidence: 99%

Hypoxia and Resistance Exercise: A Comparison of Localized and Systemic Methods

et al. 2014

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It is generally believed that optimal hypertrophic and strength gains are induced through moderate-or high-intensity resistance training, equivalent at least 60% of an individual's 1-repetition maximum (1RM). However, recent evidence suggests that similar adaptations are facilitated when low-intensity resistance exercise (~20-50% 1RM) is combined with blood flow restriction (BFR) to the working muscles. Although the mechanisms underpinning these responses are not yet firmly established, it appears that localized hypoxia created by BFR may provide an anabolic stimulus by enhancing the metabolic and endocrine response, and increase cellular swelling and signalling function following resistance exercise. Moreover, BFR has also been demonstrated to increase type II muscle fibre recruitment during exercise.However, inappropriate implementation of BFR can result in detrimental effects, including petechial haemorrhage and dizziness. Further, as BFR is limited to the limbs, the muscles of the trunk are unable to be trained under localized hypoxia. More recently, the use of systemic hypoxia via hypoxic chambers and devices has been investigated as a novel way to stimulate similar physiological responses to resistance training as BFR techniques. While little evidence is available, reports indicate that beneficial adaptations, similar to those induced by BFR, are possible using these methods. The use of systemic hypoxia allows large groups to train concurrently within a hypoxic chamber using multi-joint exercises. However, further scientific research is required to fully understand the mechanisms that cause augmented muscular changes during resistance exercise with a localized or systemic hypoxic stimulus.3

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“…Many of the anabolic actions of GH are mediated by IGF-1 [11,57], which is predominantly synthesized and released in response to circulating GH levels [58].…”

Section: Hormonal Responsesmentioning

confidence: 99%

Hypoxia and Resistance Exercise: A Comparison of Localized and Systemic Methods

et al. 2014

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“…GHRH and ghrelin, stimulate its release, while somatostatin is inhibitory. Although these hormones are known to be produced in the hypothalamus and stomach, a production in local tissues resulting in an autocrine/paracrine mode of action has been ascertained 1 . Binding sites for GH secretagogues are present in breast tissue and ghrelin exerts GH independent effects 2 although the local expression of ghrelin in breast is undetermined.…”

Section: The Gh-igf-1 Axismentioning

confidence: 99%

The GH–IGF-I axis and breast cancer

Laban

Bustin

Jenkins

2003

Trends in Endocrinology & Metabolism

109

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“…Longitudinal growth is regulated by growth hormone (GH) and its tissue mediator insulin-like growth factor-I (IGFI) (for review see Le Roith et al 13 ). GH release from the anterior pituitary is under the reciprocal control of the hypothalamic hormones growth hormone-releasing hormone (GHRH) and somatostatin.…”

Section: Introductionmentioning

confidence: 99%

Abnormalities of the somatotrophic axis in the obese agouti mouse

et al. 2005

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Objective: Abnormalities of the melanocortin system produce obesity and increased linear growth. While the obesity phenotype is well characterised, the mechanism responsible for increased linear growth is unclear. The somatotrophic axis was studied in the obese agouti (A y /a) mouse as a model of a perturbed melanocortin system. Design: Adult obese A y /a mice were compared to age-and sex-matched wild-type (WT) controls. Weight and body length (nose-anus) were recorded. Plasma growth hormone (GH), insulin-like growth factor-I (IGFI), insulin and leptin were measured using radioimmunoassay. Since ghrelin is a potent GH secretagogue, plasma ghrelin, stomach ghrelin peptide and stomach ghrelin mRNA expression were studied. Hypothalamic periventricular (PeVN) somatostatin neurones and arcuate (Arc) neuropeptide Y (NPY) neurones inhibit the growth axis, whereas Arc growth hormone-releasing hormone (GHRH) neurones are stimulatory. Therefore, specific hypothalamic expression of somatostatin, NPY and GHRH was measured using quantitative in situ hybridisation. Results: Obese A y /a mice were significantly heavier and longer than WT controls. Plasma IGFI concentrations were 30% greater in obese A y /a mice. Obese A y /a mice were hyperinsulinaemic and hyperleptinaemic, yet plasma ghrelin, and stomach ghrelin peptide and mRNA were significantly reduced. In obese A y /a mice, PeVN somatostatin and Arc NPY mRNA expression were reduced by 50% compared to WT controls, whereas Arc GHRH mRNA expression was unchanged. Conclusion: Increased body length in adult obese A y /a mice may result from reduced Arc NPY and PeVN somatostatin mRNA expression, which in turn, may increase plasma IGFI concentrations and upregulate the somatotrophic axis.

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The Somatomedin Hypothesis: 2001

Cited by 987 publications

References 203 publications

Hypoxia and Resistance Exercise: A Comparison of Localized and Systemic Methods

Hypoxia and Resistance Exercise: A Comparison of Localized and Systemic Methods

The GH–IGF-I axis and breast cancer

Abnormalities of the somatotrophic axis in the obese agouti mouse

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