Reduced growth hormone receptor messenger ribonucleic acid in an aged man with chronic malnutrition and growth hormone resistance

Effect of anthelmintic treatment on serum free IGF-1 and IGFBP-3: a cluster-randomized-controlled trial in Indonesia

In children, soil-transmitted helminth infections have been linked to poor nutritional status and growth retardation in association with lower levels of IGF-1. In adults, IGF-1 has an anabolic and metabolic function and is related to nutritional status. Here, we assessed the impact of helminth infection on free IGF-1 and its major binding protein, IGFBP-3, in adults. The levels of IGF-1 and IGFBP3 were measured in 1669 subjects aged ≥ 16 years, before and after receiving four rounds of albendazole 400 mg/day or matching placebo for three consecutive days. Helminth infection status was assessed by microscopy (Kato-Katz) and PCR. Serum free IGF-1 level was significantly lower in helminth-infected subjects [mean difference and 95% CI − 0.068 (− 0.103; − 0.033), P < 0.001 after adjustment for age, sex, body mass index, and fasting insulin level]. There was no difference in IGFBP-3 level between helminth infected versus non-infected subjects. In the whole study population, albendazole treatment significantly increased serum free IGF-1 level [estimate and 95% CI 0.031 (0.004; − 0.057), P = 0.024] whereas no effect was found on the IGFBP-3 level. Our study showed that helminth infection in adults is associated with lower free IGF-1 levels but not with IGFBP-3 and albendazole treatment significantly increases free IGF-1 levels in the study population.

Clinical Trial Registration: https://www.isrctn.com/ISRCTN75636394.

Leucine supplementation improves acquired growth hormone resistance in rats with protein-energy malnutrition

Background

Protein-energy malnutrition (PEM) can lead to growth hormone (GH) resistance. Leucine supplementation diets have been shown to increase protein synthesis in muscles. Our study aimed at investigating if long-term leucine supplementation could modulate GH-insulin-like growth factor (IGF)-1 system function and mammalian target of rapamycin (mTOR)-related signal transduction in skeletal muscles in a rat model of severe malnutrition.

Methodology/Principal Findings

Male Sprague-Dawley rats (n = 50; weight, 302 ± 5 g) were divided into 5 treatment groups, including 2 control groups (a normal control group that was fed chow and ad libitum water [CON, n = 10] and a malnourished control group [MC, n = 10] that was fed a 50% chow diet). After undergoing a weight loss stage for 4 weeks, rats received either the chow diet (MC-CON, n = 10), the chow diet supplemented with low-dose leucine (MC-L, n = 10), or the chow diet supplemented with high-dose leucine (MC-H, n = 10) for 2 weeks. The muscle masses of the gastrocnemius, soleus, and extensor digitorum longus were significantly reduced in the MC group. Re-feeding increased muscle mass, especially in the MC-L and MC-H groups. In the MC group, serum IGF-1, IGF-binding protein (IGFBP)-3, and hepatic growth hormone receptor (GHR) levels were significantly decreased and phosphorylation of the downstream anabolic signaling effectors protein kinase B (Akt), mTOR, and ribosomal protein S6 kinase 1 (S6K1) were significantly lower than in other groups. However, serum IGF-1 and IGF binding protein (IGFBP)-3 concentrations and hepatic growth hormone receptor (GHR) levels were significantly higher in the MC-L and MC-H groups than in the MC-CON group, and serum IGFBP-1 levels was significantly reduced in the MC-L and MC-H groups. These changes were consistent with those observed for hepatic mRNA expression levels. Phosphorylation of the downstream anabolic signaling effectors Akt, mTOR, and S6K1 were also significantly higher in the MC-L and MC-H groups than in the MC-CON group.

Conclusion/Significance

Our data are the first to demonstrate that long-term supplementation with leucine improved acquired growth hormone resistance in rats with protein-energy malnutrition. Leucine might promote skeletal muscle protein synthesis by regulating downstream anabolic signaling transduction.

GH-binding protein is related to bone mineral density in non-obese androgenized women

GH and IGF system components are important regulators of bone formation and at the same time pathogenetic factors in functional hyperandrogenism (FH) in lean females. We studied the relationships between bone mineral density (BMD) and serum concentrations of GH, GH-related parameters, androgens and estrogen, in 18 non-obese women of reproductive age with functional hyperandrogenism compared to a group of 10 healthy eumenorrheic age- and weight-matched women. In androgenized women, a significant positive correlation was found between BMD and GH-binding protein (GHBP), whereas BMD did not correlate to GH or other related parameters. It is suggested that higher tissue GH receptor responsiveness in non-obese androgenized women may contribute to their higher BMD.