Breast milk stimulates growth hormone secretion in infant mice, and phosphorus insufficiency disables this ability and causes dwarfism-like symptoms

Association Between Serum Calcium and Phosphorus Levels and Insulin-Like Growth Factor-1 in Chinese Children and Adolescents with Short Stature

Objective

The aim of this study was to investigate the effect of serum calcium and phosphorus levels on the insulin-like growth factor 1 (IGF-1) in Chinese children and adolescents with short stature.

Methods

In this cross-sectional analysis, the clinical data of 747 children with height below –2 SD who were evaluated at the Department of Endocrinology, Affiliated Hospital of Jining Medical University from March 1, 2013, to February 28, 2019, were selected. Anthropometric and biochemical indicators were measured. The relationship between the serum calcium and phosphorus levels and IGF-1 was analysed.

Results

The univariate analysis results showed that serum calcium or phosphorus was significantly associated with IGF-1 SDS. In addition, after adjusting for possible confounding factors, a linear relationship between serum calcium and IGF-1 SDS and a non-linear relationship between serum phosphorus and IGF-1 SDS were observed by smooth curve fitting. The results of the fully adjusted linear regression showed that serum calcium was positively associated with IGF-1 SDS (β 1.07, 95% CI 0.21, 1.92; p = 0.015). In the multivariate piecewise linear regression, when the serum phosphorus level was greater than 1.26 mmol/L, the IGF-1 SDS increased with the increase in serum phosphorus (β 1.92, 95% CI 1.36, 2.48; p < 0.001). However, we did not observe a significant relationship when the serum phosphorus level was less than 1.26 mmol/L (p = 0.223).

Conclusion

This study demonstrated that in Chinese children and adolescents with short stature, circulating calcium and phosphorus concentrations may be associated with the regulation of IGF-1 levels, and this relationship merits further investigation.

All You Can Feed: Some Comments on Production of Mouse Diets Used in Biomedical Research with Special Emphasis on Non-Alcoholic Fatty Liver Disease Research

The laboratory mouse is the most common used mammalian research model in biomedical research. Usually these animals are maintained in germ-free, gnotobiotic, or specific-pathogen-free facilities. In these facilities, skilled staff takes care of the animals and scientists usually don’t pay much attention about the formulation and quality of diets the animals receive during normal breeding and keeping. However, mice have specific nutritional requirements that must be met to guarantee their potential to grow, reproduce and to respond to pathogens or diverse environmental stress situations evoked by handling and experimental interventions. Nowadays, mouse diets for research purposes are commercially manufactured in an industrial process, in which the safety of food products is addressed through the analysis and control of all biological and chemical materials used for the different diet formulations. Similar to human food, mouse diets must be prepared under good sanitary conditions and truthfully labeled to provide information of all ingredients. This is mandatory to guarantee reproducibility of animal studies. In this review, we summarize some information on mice research diets and general aspects of mouse nutrition including nutrient requirements of mice, leading manufacturers of diets, origin of nutrient compounds, and processing of feedstuffs for mice including dietary coloring, autoclaving and irradiation. Furthermore, we provide some critical views on the potential pitfalls that might result from faulty comparisons of grain-based diets with purified diets in the research data production resulting from confounding nutritional factors.

Deletion of muscle IGF-I transiently impairs growth and progressively disrupts glucose homeostasis in male mice

Insulin-like growth factors (IGFs) are essential for local skeletal muscle growth and organismal physiology, but these actions are entwined with glucose homeostasis through convergence with insulin signaling. The objective of this work was to determine whether the effects of IGF-I on growth and metabolism could be separated. We generated muscle-specific IGF-I-deficient (MID) mice that afford inducible deletion of Igf1 at any age. After Igf1 deletion at birth or in young adult mice, evaluations of muscle physiology and glucose homeostasis were performed up to 16 wk of age. MID mice generated at birth had lower muscle and circulating IGF-I, decreased muscle and body mass, and impaired muscle force production. Eight-wk-old male MID had heightened insulin levels with trends of elevated fasting glucose. This phenotype progressed to impaired glucose handling and increased fat deposition without significant muscle mass loss at 16 wk of age. The same phenotype emerged in 16-wk-old MID mice induced at 12 wk of age, compounded with heightened muscle fatigability and exercise intolerance. We assert that muscle IGF-I independently modulates anabolism and metabolism in an age-dependent manner, thus positioning muscle IGF-I maintenance to be critical for both muscle growth and metabolic homeostasis.-Vassilakos, G., Lei, H., Yang, Y., Puglise, J., Matheny, M., Durzynska, J., Ozery, M., Bennett, K., Spradlin, R., Bonanno, H., Park, S., Ahima, R. S., Barton, E. R. Deletion of muscle IGF-I transiently impairs growth and progressively disrupts glucose homeostasis in male mice.