Neonatal taurine administration modifies metabolic programming in male mice

Nutrition and human health from a sex-gender perspective

Nutrition exerts a life-long impact on human health, and the interaction between nutrition and health has been known for centuries. The recent literature has suggested that nutrition could differently influence the health of male and female individuals. Until the last decade of the 20th century, research on women has been neglected, and the results obtained in men have been directly translated to women in both the medicine and nutrition fields. Consequently, most modern guidelines are based on studies predominantly conducted on men. However, there are many sex-gender differences that are the result of multifactorial inputs, including gene repertoires, sex steroid hormones, and environmental factors (e.g., food components). The effects of these different inputs in male and female physiology will be different in different periods of ontogenetic development as well as during pregnancy and the ovarian cycle in females, which are also age dependent. As a result, different strategies have evolved to maintain male and female body homeostasis, which, in turn, implies that there are important differences in the bioavailability, metabolism, distribution, and elimination of foods and beverages in males and females. This article will review some of these differences underlying the impact of food components on the risk of developing diseases from a sex-gender perspective.

A maternal low protein diet has pronounced effects on mitochondrial gene expression in offspring liver and skeletal muscle; protective effect of taurine

Background

Low birth weight is associated with an increased risk of developing impaired glucose tolerance, and eventually type 2 diabetes in adult life. Gestational protein restriction in rodents gives rise to a low birth weight phenotype in the offspring.

Results

We examined gene expression changes in liver and skeletal muscle of mice subjected to gestational protein restriction (LP) or not (NP), with or without taurine supplementation in the drinking water. LP offspring had a 40% lower birth weight than NP offspring, with taurine preventing half the decrease. Microarray gene expression analysis of newborn mice revealed significant changes in 2012 genes in liver and 967 genes in skeletal muscle of LP offspring. Taurine prevented 30% and 46% of these expression changes, respectively. Mitochondrial genes, especially those involved with oxidative phosphorylation, were more abundantly changed than other genes. The mitochondrial genes were mainly upregulated in liver, but downregulated in skeletal muscle, despite no change in citrate synthase activity in either tissue. Taurine preferentially rescued genes concerned with fatty acid metabolism in liver and with oxidative phosphorylation and TCA cycle in skeletal muscle. A mitochondrial signature was seen in the liver of NP offspring with taurine supplementation, as gene sets for mitochondrial ribosome as well as lipid metabolism were over represented in 4-week-old offspring subjected to gestational taurine supplementation. Likewise, 11 mitochondrial genes were significantly upregulated by gestational taurine supplementation in 4-week-old NP offspring.

Conclusions

Gestational protein restriction resulted in lower birth weight associated with significant gene expression changes, which was different in liver and muscle of offspring. However, a major part of the birth weight decrease and the expression changes were prevented by maternal taurine supplementation, implying taurine is a key factor in determining expression patterns during development and in that respect also an important component in metabolic fetal programming.

Taurine supplementation: involvement of cholinergic/phospholipase C and protein kinase A pathways in potentiation of insulin secretion and Ca2+ handling in mouse pancreatic islets

Taurine (TAU) supplementation increases insulin secretion in response to high glucose concentrations in rodent islets. This effect is probably due to an increase in Ca2+ handling by the islet cells. Here, we investigated the possible involvement of the cholinergic/phospholipase C (PLC) and protein kinase (PK) A pathways in this process. Adult mice were fed with 2% TAU in drinking water for 30 d. The mice were killed and pancreatic islets isolated by the collagenase method. Islets from TAU-supplemented mice showed higher insulin secretion in the presence of 8.3 mm-glucose, 100 μm-carbachol (Cch) and 1 mm-3-isobutyl-1-methyl-xanthine (IBMX), respectively. The increase in insulin secretion in response to Cch in TAU islets was accompanied by a higher intracellular Ca2+ mobilisation and PLCβ2 protein expression. The Ca2+ uptake was higher in TAU islets in the presence of 8.3 mm-glucose, but similar when the islets were challenged by glucose plus IBMX. TAU islets also showed an increase in the expression of PKAα protein. This protein may play a role in cation accumulation, since the amount of Ca2+ in these islets was significantly reduced by the PKA inhibitors: N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinoline sulfonamide (H89) and PK inhibitor-(6-22)-amide (PKI). In conclusion, TAU supplementation increases insulin secretion in response to glucose, favouring both influx and internal mobilisation of Ca2+, and these effects seem to involve the activation of both PLC-inositol-1,4,5-trisphosphate and cAMP-PKA pathways.

Gestational protein restriction in mice has pronounced effects on gene expression in newborn offspring's liver and skeletal muscle; protective effect of taurine

We examined gene expression changes in liver and skeletal muscle of newborn mice subjected to a maternal low protein (LP) or normal protein (NP) diet during pregnancy, with or without taurine supplementation in the drinking water. LP offspring had a 40% lower birthweight than NP offspring, whereas it was reduced by only 20% with taurine supplementation. Microarray gene expression analysis revealed significant changes in 2012 genes in liver and 967 genes in skeletal muscle of LP offspring. By unknown mechanisms, taurine partially or fully prevented 30 and 46% of these expression changes, respectively. Mitochondrial genes, in particular genes associated with oxidative phosphorylation, were more abundantly changed in LP offspring, with primarily up-regulation in liver but down-regulation in skeletal muscle. In both tissues, citrate synthase activity remained unchanged. Taurine preferentially rescued changes in genes concerned with fatty acid metabolism in liver and with oxidative phoshorylation and tri carboxylic acid (TCA) cycle in skeletal muscle.

ABBREVIATIONS

Gestational protein restriction resulted in lower birthweight associated with significant gene expression changes, which was different in liver and muscle of offspring. However, a major part of the birthweight decrease and the expression changes were prevented by maternal taurine supplementation, implying taurine is a key component in metabolic fetal programming.

Taurine supplementation enhances nutrient-induced insulin secretion in pancreatic mice islets

BACKGROUND

Taurine (TAU), a naturally occurring sulfur-containing amino acid, is found at high concentrations in plasma and mammalian tissues and regulates osmolarity, ion channel activity, and glucose homeostasis. Several reports have shown that physiological plasma TAU levels seem to be important for adequate beta (beta)-cell function and insulin action, since low concentrations of TAU in the plasma have been reported in the pre-diabetic and diabetic states.

METHODS

Glucose tolerance and insulin sensitivity were investigated in mice supplemented with 2% (w/v) TAU in their drinking water for 30 days, as well as the insulin secretion from isolated islets stimulated by glucose or L-leucine.

RESULTS

TAU-supplemented mice demonstrated improved glucose tolerance and higher insulin sensitivity, compared to controls (CTL). In addition, their islets secreted more insulin in response to high concentrations of glucose and L-leucine. L-[U-(14)C]leucine oxidation was higher in TAU than in CTL islets, whereas D-[U-(14)C]glucose oxidation, ATP levels, glucose transporter (GLUT) 2 and glucokinase (GCK) protein expressions were similar in both types of islets. The L-type beta(2) subunit voltage-sensitive Ca(2+) channel protein, as well as (45)Ca uptake, were significantly higher in TAU-supplemented than CTL islets. In addition, islets from TAU-supplemented mice secreted more glucagon than CTL islets at low glucose.

CONCLUSIONS

TAU supplementation improves glucose tolerance and insulin sensitivity in mice, as well as insulin secretion from isolated islets. The latter effect seems to be, at least in part, dependent on a better Ca(2+) handling by the islets.

Are the available experimental models of type 2 diabetes appropriate for a gender perspective?

Several experimental models have so far been developed to improve our knowledge of the pathogenetic mechanisms of type 2 diabetes mellitus (T2D), to determine the possible pharmacological targets of this disease and to better evaluate diabetes-associated complications, e.g. the cardiovascular disease. In particular, the study of T2D gained the attention of several groups working with different animal species: rodents, cats or pigs, as well as other non-human primate species. Each of these species provided useful and different clues. However, T2D has to be considered as a gender-associated disease: sex differences play in fact a key role in the onset as well as in the progression of the disease and a higher mortality for cardiovascular diseases is detected in diabetic women with respect to men. The results obtained from all the available animal models appear to only partially address this issue so that the search for more precise information in this respect appears to be mandatory. In this review we summarize these concepts and literature in the field and propose a reappraisal of the various animal models for a study of T2D that would take into consideration a gender perspective.