GLP-2: What do we know? What are we going to discover?

Glucagon-like peptide 2 [GLP-2] is a 33-amino acid peptide released from themucosal enteroendocrine L-cells of the intestine. The actions of GLP-2 are transduced by the GLP-2 receptor [GLP-2R], which is localized in the neurons of the enteric nervous system but not in the intestinal epithelium, indicating an indirect mechanism of action. GLP-2 is well known for its trophic role within the intestine and interest in GLP-2 is now reviving based on the approval of the GLP-2R agonist for treatment of short bowel syndrome [SBS]. Recently it also seems to be involved in glucose homeostasis. The aimof this reviewis to outline the importance of neuroendocrine peptides, specifically of GLP-2 in the enteric modulation of the gastrointestinal function and to focus on new works in order to present an innovative picture of GLP-2

Glucagon-Like Peptide-1 Modulates Neurally-Evoked Mucosal Chloride Secretion in Guinea Pig Small Intestine In Vitro.

Glucagon-like peptide-1 (GLP-1) acts at the G protein-coupled receptor, GLP-1R, to stimulate secretion of insulin and to inhibit secretion of glucagon and gastric acid. Involvement in mucosal secretory physiology has received negligible attention. We aimed to study involvement of GLP-1 in mucosal chloride secretion in the small intestine. Ussing chamber methods, in concert with transmural electrical field stimulation (EFS), were used to study actions on neurogenic chloride secretion. ELISA was used to study GLP-1R effects on neural release of acetylcholine (ACh). Intramural localization of GLP-1R was assessed with immunohistochemistry. Application of GLP-1 to serosal or mucosal sides of flat-sheet preparations in Ussing chambers did not change baseline short-circuit current (Isc), which served as a marker for chloride secretion. Transmural EFS evoked neurally mediated biphasic increases in Isc that had an initial spike-like rising phase followed by a sustained plateau-like phase. Blockade of the EFS-evoked responses by tetrodotoxin indicated that the responses were neurally mediated. Application of GLP-1 reduced the EFS-evoked biphasic responses in a concentration-dependent manner. The GLP-1 receptor antagonist exendin-(9 –39) suppressed this action of GLP-1. The GLP-1 inhibitory action on EFS-evoked responses persisted in the presence of nicotinic or vasoactive intestinal peptide receptor antagonists but not in the presence of a muscarinic receptor antagonist. GLP-1 significantly reduced EFS-evoked ACh release. In the submucosal plexus, GLP-1R immunoreactivity (IR) was expressed by choline acetyltransferase- IR neurons, neuropeptide Y-IR neurons, somatostatin-IR neurons, and vasoactive intestinal peptide-IR neurons. Our results suggest that GLP-1R is expressed in guinea pig submucosal neurons and that its activation leads to a decrease in neurally evoked chloride secretion by suppressing release of ACh at neuroepithelial junctions in the enteric neural networks that control secretomotor functions

Effects of protein supplementation in fitness world: A 12-week cross-over studio

The aim of this project was to evaluate the effect of isolated protein supplementation in young amateur athletes. Sixteen subjects aged between 20 and 30 were recruited for this study. Before to start sports performance was assessed at T0, in all subjects, using physical performance test and evaluated body composition. Therefore, the subjects were randomly assigned in two groups (group A and B) of 8 subjects each. The group A start to intake 30 g of protein powder diluted in water after each training session (3 times a week) for six weeks (T0) whilst the group B was the placebo. After 6 weeks (T1), the measurement were repeated for all subjects and the group A became placebo and the group B started with the supplementation. At the end of 6 weeks (T2) we carried out all the tests were performed again. Results showed a significant improvement in almost all tests between T0 and T2 within the same group (p < .05), but not significant difference was found between the start and the end of protein’s intake period in both groups. In conclusion, supplementation did not have affect the performance and body composition significantly. Instead, training seems to influence the performance more the supplementation

Physical activity, nutrition and bone health

This review aims to describe the roles that physical activity and nutrition have in bone metabolism and to examine their effects on bone in a situation of altered metabolism as a consequence of inadequate nutrition and/or excessive physical activity. Referring to the recent studies and the main guidelines in the literature on athlete nutrition, the paper also focuses on essential nutrients for bone health during performance. Finally, it discusses the negative effect of some nutrients on bone mineral density

Glucagon-like peptide-2 modulates neurally evoked mucosal chloride secretion in guinea pig small intestine in vitro

Glucagon-like peptide-2 (GLP-2) is an important neuroendocrine peptide in intestinal physiology. It influences digestion, absorption, epithelial growth, motility, and blood flow. We studied involvement of GLP-2 in intestinal mucosal secretory behavior. Submucosal-mucosal preparations from guinea pig ileum were mounted in Ussing chambers for measurement of shortcircuit current (Isc) as a surrogate for chloride secretion. GLP-2 action on neuronal release of acetylcholine was determined with ELISA. Enteric neuronal expression of the GLP-2 receptor (GLP-2R) was studied with immunohistochemical methods. Application of GLP-2 (0.1–100 nM) to the serosal or mucosal side of the preparations evoked no change in baseline Isc and did not alter transepithelial ionic conductance. Transmural electrical field stimulation (EFS) evoked characteristic biphasic increases in Isc, with an initially rapid rising phase followed by a sustained phase. Application of GLP-2 reduced the EFS-evoked biphasic responses in a concentration-dependent manner. The GLP-2R antagonist GLP-2-(3-33) significantly reversed suppression of the EFS-evoked responses by GLP-2. Tetrodotoxin, scopolamine, and hexamethonium, but not vasoactive intestinal peptide type 1 receptor (VPAC1) antagonist abolished or reduced to near zero the EFS-evoked responses. GLP-2 suppressed EFS-evoked acetylcholine release as measured by ELISA. Pretreatment with GLP-2- (3-33) offset this action of GLP-2. In the submucosal plexus, GLP-2R immunoreactivity (-IR) was expressed in choline acetyltransferase-IR neurons, somatostatin-IR neurons, neuropeptide Y-IR neurons, and vasoactive intestinal peptide-IR neurons. We conclude that submucosal neurons in the guinea pig ileum express GLP-2R. Activation of GLP-2R decreases neuronally evoked epithelial chloride secretion by suppressing acetylcholine release from secretomotor neurons

The Impact of Diet and Physical Activity on Bone Health in Children and Adolescents

There is growing recognition of the role of diet and physical activity in modulating bone mineral density, bone mineral content, and remodeling, which in turn can impact bone health later in life. Adequate nutrient composition could influence bone health and help to maximize peak bone mass. Therefore, children’s nutrition may have lifelong consequences. Also, physical activity, adequate in volume or intensity, may have positive consequences on bone mineral content and density and may preserve bone loss in adulthood. Most of the literature that exists for children, about diet and physical activity on bone health, has been translated from studies conducted in adults. Thus, there are still many unanswered questions about what type of diet and physical activity may positively influence skeletal development. This review focuses on bone requirements in terms of nutrients and physical activity in childhood and adolescence to promote bone health. It explores the contemporary scientific literature that analyzes the impact of diet together with the typology and timing of physical activity that could be more appropriate depending on whether they are children and adolescents to assure an optimal skeleton formation. A description of the role of parathyroid hormone (PTH) and gut hormones (gastric inhibitory peptide (GIP), glucagon-like peptide (GLP)-1, and GLP-2) as potential candidates in this interaction to promote bone health is also presented

Dare to jump: The effect of the new high impact activity SuperJump on bone remodeling. A new tool to maintain fitness during COVID-19 home confinement

SuperJump is a high impact activity performed on an elastic trampoline that mixes aerobic and anaerobic exercises already proposed as home-based activity for preventing a sedentary lifestyle. We determined in a randomized controlled trial whether 20 weeks of SuperJump activity would promote bone formation and reduce resorption in eumenorrheic women. Twenty-four women were randomized to a non-exercise group (control group) or an exercise group that performed SuperJump activity three times a week for 20 weeks. Blood samples were collected in both groups at baseline and at the end of the 20 weeks and compared within and between the groups for C-terminal telopeptide (CTX), a marker of bone resorption, osteocalcin, a marker of bone formation, and the markers of bone metabolism parathyroid hormone (PTH), calcitonin, albumin-adjusted calcium (Aa calcium), vitamin D, phosphate and potassium. After 20 weeks of SuperJump activity, levels of CTX were significantly reduced while levels of osteocalcin were increased. PTH, calcium and potassium were involved in the mechanism of action because PTH was reduced while calcium and potassium were increased. Calcitonin, vitamin D and phosphate levels did not change. These data suggest that SuperJump activity is able to reduce bone resorption and improve bone formation by acting on essential regulators of bone metabolism. They also suggest that SuperJump training may be used as a valuable intervention to prevent the occurrence of osteoporosis in aging because it improves bone homeostasis in favor of bone formation and could counteract a sedentary lifestyle, such as during COVID-19 home confinement, which could itself contribute to the variation of bone metabolism. Trial registration: Clinicaltrials.gov NCT04942691 \u2013retrospectively registered

Analysis of Body Perception, Preworkout Meal Habits and Bone Resorption in Child Gymnasts

The beneficial effects of physical activity on body image perception and bone are debated among artistic gymnasts. Gymnasts seem to be at greater risk of developing body dissatisfaction, eating disorders and osteoporosis due to inadequate nutrition and attention to the appearance of the body. The objective of this work was to investigate the association between the artistic gymnast and a more favorable body image compared to their sedentary peers and if a preworkout high-carbohydrate meal (HCM; 300 kcal, 88% carbohydrates, 9% protein, 3% fat) or high-protein meal (HPM; 300 kcal, 55% carbohydrates, 31% protein, 13% fat) is able to attenuate bone resorption in young rhythmic gymnasts. Twenty-eight preadolescent female gymnasts were examined. Self-esteem tests were used to analyze body image perception. Preworkout eating habits were examined by short food frequency questions (FFQ) validated for children. The biomarker of the bone resorption C-terminal telopeptide region of collagen type 1 (CTX) was measured in the urine (fasting, postmeal and postworkout). Gymnasts reported higher satisfaction with their body appearance compared to sedentary peers. Of the gymnasts, 30% did not have a preworkout meal regularly, and the timing of the consumption was variable. Bone resorption was decreased by the HCM, consumed 90 min before the training, with respect to the HPM. The study suggests that playing artistic gymnastics is associated with a positive body self-perception in a child. The variability in preworkout meal frequency and timing need attention to prevent inadequate eating habits in light of the ability of the HCM to reduce acute bone resorption