Gastrointestinal absorption of insulin-like growth factor in the mouse in the absence of salivary insulin-like growth factor binding protein

Nakagawa, Yoichi; Oxford, Gregory E.; Ishibashi, Keiichiro; Yamamoto, Hideo; Maeda, Nobuyo; Bowen, Elizabeth J.; Brayer, Jason; Humphreys‐Beher, Michael G.

doi:10.1016/s0006-2952(96)00733-2

Cited by 6 publications

(5 citation statements)

References 29 publications

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“…In addition to the direct role that such growth factors might have on growth and development of the intestine, substantial evidence now exists that specific peptides such as IGF‐1 may not only remain in receptor active form within the suckling intestine for as long as 30 minutes post ingestion (16), but may also be absorbed into the circulation in biologically relevant amounts (7). Some evidence has been presented that this process may also occur in the adult mouse (23). The mechanism(s) by which intestinal absorption of intact polypeptides might occur in animals is not well described, however.…”

Section: Discussionmentioning

confidence: 99%

Intestinal Transport of Insulin‐Like Growth Factor‐I (IGF‐I) in the Suckling Rat

Philipps,

Kling,

Grille

et al. 2002

J. pediatr. gastroenterol. nutr.

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ObjectivesInsulin‐Like Growth Factor‐1 is a potent growth‐promoting peptide that is present in mammalian milk. Previous studies have suggested that milk‐borne IGF‐1 may be absorbed intact from the gastrointestinal tract of the suckling but the mechanism responsible for such transport is not well documented. The present study was designed to investigate in an in vivo suckling rat model whether or not intestinal absorption of IGF‐1 is a saturable phenomenon.MethodsSuckling rats (10–12 days postnatal age) were studied under anesthesia. A jejunal loop from each rat pup was isolated and injected intraluminally with 1–2 × 105 cpm of rh125I‐IGF‐I. Injections were performed in paired littermates either with or without a preceding injection of unlabeled IGF‐I of 20, 500, or 1000 ng/ml concentration. After flushing, the loops and livers were homogenized and counted in a gamma counter. In addition, homogenates of jejunum and liver were precipitated with trichloroacetic acid (TCA) and the precipitates also counted. In selected instances (jejunum), acid gel chromatography of homogenates was also performed.ResultsRetention of radioactivity was observed in all jejunal specimens, but the pre‐incubation of jejunal loops with unlabeled IGF‐1 was associated with a biphasic response, i.e. at low dose (20 ng/ml) pre‐incubation limited retention of radioactivity, but at a high dose (1000 ng/ml), retention was enhanced (P < 0.05). Linear regression analysis confirmed this inverse relationship. Liver radioactivity followed a similar pattern. Between 40 and 49% of the radioactivity in jejunal and liver homogenates was TCA precipitable. Chromatography of jejunal homogenates showed that approximately 40% of cpm migrated in a position identical with that of intact IGF‐1.ConclusionsThe intestinal uptake of IGF‐1 in the suckling is nonsaturable, confirming previous in vitro studies and suggesting that a nonreceptor‐dependent method of transepithelial transport is important in this process.

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Section: Discussionmentioning

confidence: 99%

Intestinal Transport of Insulin‐Like Growth Factor‐I (IGF‐I) in the Suckling Rat

Philipps,

Kling,

Grille

et al. 2002

J. pediatr. gastroenterol. nutr.

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“…Salivatin is probably absorbed from digestive organs after nutrient ingestion, and may potentiate glucose‐stimulated insulin release in humans as well. Recent studies have demonstrated that saliva‐derived epidermal growth factor (EGF) and insulin‐like growth factor 1 are absorbed through the oral cavity and or the gastrointestinal tract in rat and mice[22,23]. Salivatin may also be absorbed through the mucosa of those digestive organs.…”

Section: Discussionmentioning

confidence: 99%

Reduction of incretin‐like salivatin in saliva from patients with type 2 diabetes and in parotid glands of streptozotocin‐diabetic BALB/c mice

Kimura

Sasamoto²,

Sasamura

et al. 2001

Diabetes Obesity Metabolism

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“…The have been found in both BALB/C and diabetic NOD mice sera with molecular masses between 25 and 45 kDa but not in their saliva. In diabetic mice, there was a detectable change in the concentrations of IGFBPs relative to BALB/C mice, which resulted in higher uptakes of IGF-I and IGF-II in mice saliva independently of specific IGFBPs (71). Concentration of IGF-I in the bovine milk was lower than that in human milk, but similar to that in human saliva; the IGF-I concentration in milk was higher in early lactation than during mid and late lactation (72).…”

Section: Insulin-like Growth Factor (Igf)mentioning

confidence: 92%

Multifunctional roles of growth factors or biologically active peptides in salivary glands and saliva

Mori

Sumitomo

Shrestha³

et al. 2008

Oral Med Pathol

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Gastrointestinal absorption of insulin-like growth factor in the mouse in the absence of salivary insulin-like growth factor binding protein

Cited by 6 publications

References 29 publications

Intestinal Transport of Insulin‐Like Growth Factor‐I (IGF‐I) in the Suckling Rat

Intestinal Transport of Insulin‐Like Growth Factor‐I (IGF‐I) in the Suckling Rat

Reduction of incretin‐like salivatin in saliva from patients with type 2 diabetes and in parotid glands of streptozotocin‐diabetic BALB/c mice

Multifunctional roles of growth factors or biologically active peptides in salivary glands and saliva

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