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Growth hormone (GH) action is primarily mediated by insulin-like growth factor I (IGF-I), although both growth factors show tissue-selective effects. We investigated the effects of GH, IGF-I, and GH plus IGF-I on jejunal growth and function in rats maintained with total parenteral nutrition (TPN) and given recombinant human GH (rhGH) (400 micrograms/day sc, twice daily) and/or rhIGF-I (800 micrograms/day in TPN solution) for 5 days. Administration of GH or IGF-I alone produced similar increases in serum IGF-I levels and body weight; GH plus IGF-I further increased these parameters. TPN reduced mucosal mass, protein and DNA content, villus height, crypt depth, and enterocyte migration rate. IGF-I or GH plus IGF-I produced equivalent increases in all intestinal growth parameters; GH alone had no effect. GH, IGF-I, or GH plus IGF-I reduced TPN-induced increases in sucrase-specific activity. IGF-I, but not GH, attenuated TPN-induced increases in tissue conductance and carbachol-stimulated ion secretion. In contrast to IGF-I, GH does not stimulate intestinal growth during TPN and has less effect on normalizing TPN-induced changes in epithelial function.

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Diabetes mellitus (DM) is a chronic metabolic disease characterized by hyperglycemia with defects in insulin secretion and/or insulin resistance. Despite great efforts that have been made in the understanding and management of diabetes, its prevalence continues to grow. Recent discoveries have opened up an exciting opportunity for developing new types of therapeutics from medicinal mushrooms to control DM and its complications. To date, more and more active components including polysaccharides and their protein complexes, dietary fibers, and other compounds extracted from fruiting bodies, cultured mycelium, or cultured broth of medicinal mushrooms have been reported as to having anti-hyperglycemic activity. These compounds exhibit their antidiabetic activity via different mechanisms. This article presents an overview of the multiple aspects of diabetes mellitus and the efficacy and mechanism of medicinal mushrooms for glucose control in diabetes, including the inhibition of glucose absorption, protection of beta-cell damage, increase of insulin release, enhancement of antioxidant defense, attenuation of inflammation, modulation of carbohydrate metabolism pathway, and regulation of insulin-dependent and insulin-independent signaling pathways. However, there is insufficient evidence to draw definitive conclusions about the efficacy of individual medicinal mushrooms for diabetes. In addition, the wide variability, the lack of standards for production, and the lack of testing protocols to assess product quality are still problems in producing medicinal mushroom products. Moreover, well-designed randomized controlled trials with long-term consumption are needed to guarantee the bioactivity and safety of medicinal mushroom products for diabetic patients.

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Our previous study demonstrated that the fruiting bodies of Cordyceps sinensis, a traditional Chinese medicine, attenuated diabetes-induced weight loss, polydipsia, and hyperglycemia in rats. In the present study, we further compared the anti-hyperglycemic activity of the fermented mycelia and broth of Cordyceps sinensis with that of the fruiting bodies. Male Wistar rats orally administered a placebo (STZ group), fruiting bodies (FB group, 1 g/day), fermented mycelia (MCS group, 1 g/day), fermented broth (BCS group, 1 g/day), or fermented mycelia plus broth (XCS group, 0.5 g/day of each) of Cordyceps sinensis (d1 to d28) were injected with nicotinamide (200 mg/kg) and streptozotocin (65 mg/kg) on d15. Rats fed with a placebo and injected with saline served as the control (CON) group. The amount of water and food consumption (d15 to d29), the 2-hour-postprandial blood glucose concentrations (d21 and d28), and the serum concentrations of fructosamine (d29) were significantly lower in the FB, MCS, BCS, and XCS groups than in the STZ group (one-way ANOVA, p < 0.05). The diabetic rats had significantly higher blood glucose concentrations as measured by the oral glucose tolerance test than the control rats; moreover, these changes were significantly reduced by ingesting the fruiting bodies, fermented mycelia and/or broth of Cordyceps sinensis. Our results revealed that the fermented mycelia and broth of Cordyceps sinensis have anti-hyperglycemic activities similar to those of the fruiting bodies. Therefore, the fermented products of Cordyceps sinensis could be developed as potential anti-diabetic agents or functional foods for persons with a high risk of diabetes mellitus.

We compared the effects of recombinant human insulin-like growth factor I [rhIGF-I, 800 micrograms/day, coinfused with total parenteral nutrition (TPN)], growth hormone (rhGH, 800 micrograms/day, subcutaneous injection twice daily), and simultaneous treatment with rhIGF-I and rhGH (800 + 800 micrograms/day) in rats subjected to surgical stress and maintained with TPN. Weight gain induced by IGF-I plus GH was double that shown by IGF-I or GH alone. Although weight gain was similar with IGF-I or GH, IGF-I selectively increased heart, kidney, thymus, spleen, and small intestine mass, whereas GH selectively increased gastrocnemius muscle mass. IGF-I and/or GH increased carcass protein and water while decreasing fat. Serum total and free IGF-I levels were highest with IGF-I plus GH. Serum rat GH levels were reduced with IGF-I and/or GH. IGF-I given with GH reversed the GH-induced increase in serum insulin. In summary, IGF-I and GH show tissue-specific anabolic effects, and simultaneous treatment with IGF-I plus GH additively increases anabolism during TPN.