Ghrelin, insulin and pancreatic activity in the peri-weaning period of goat kids

Intestinal perfusion of unacylated ghrelin alleviated metabolically associated fatty liver disease in rats via a central glucagon-like peptide-1 pathway

Unacylated ghrelin (UAG), the unacylated form of ghrelin, accounts for 80%-90% of its circulation. Accumulated studies have pointed out that UAG may be used to treat metabolic disorders. This study aimed to investigate the effect of intestinal perfusion of UAG on metabolically associated fatty liver disease (MAFLD) induced by a high-fat diet and its possible mechanisms. Neuronal retrograde tracking combined with immunofluorescence, central administration of a glucagon-like peptide-1 receptor (GLP-1R) antagonist, and hepatic vagotomy was performed to reveal its possible mechanism involving a central glucagon-like peptide-1 (GLP-1) pathway. The results showed that intestinal perfusion of UAG significantly reduced serum lipids, aminotransferases, and food intake in MAFLD rats. Steatosis and lipid accumulation in the liver were significantly alleviated, and lipid metabolism-related enzymes in the liver were regulated. UAG upregulated the expression of GLP-1 receptor (GLP-1R) in the paraventricular nucleus (PVN) and GLP-1 in the nucleus tractus solitarii (NTS), as well as activated GLP-1 neurons in the NTS. Furthermore, GLP-1 fibers projected from NTS to PVN were activated by the intestinal perfusion of UAG. However, hepatic vagotomy and GLP-1R antagonists delivered into PVN before intestinal perfusion of UAG partially attenuated its alleviation of MAFLD. In conclusion, intestinal perfusion of UAG showed a therapeutic effect on MAFLD, which might be related to its activation of the GLP-1 neuronal pathway from NTS to PVN. The present results provide a new strategy for the treatment of MAFLD.NEW & NOTEWORTHY Intestinal perfusion of UAG, the unacylated form of ghrelin, has shown promising potential for treating MAFLD. This study unveils a potential mechanism involving the central GLP-1 pathway, with UAG upregulating GLP-1R expression and activating GLP-1 neurons in specific brain regions. These findings propose a novel therapeutic strategy for MAFLD treatment through UAG and its modulation of the GLP-1 neuronal pathway.

Insights on discovery, efficacy, safety and clinical applications of ghrelin receptor agonist capromorelin in veterinary medicine

Growth hormone and insulin like growth factor-1 plays an important role in the regulation of body composition and metabolism. Growth Hormone is released from the pituitary through a specific G-protein coupled receptor (GPCR) called growth hormone secretagogue receptor 1a expressed in the hypothalamus. Ghrelin is a peptide hormone released from the cells in the stomach, which stimulates appetite and food intake in mammals, regulates gut motility, gastric acid secretion, taste sensation, circadian rhythm, learning and memory, oxidative stress, autophagy, glucose metabolism etc. When the release of the endogenous ligand GHSR-1a, i.e., ghrelin is malfunctioned or stopped, external substitutes are administrated to induce the stimulation of growth hormone and appetite. A class of compound known as ghrelin receptor agonists are developed as an external substitute of ghrelin for regulation and stimulation of growth hormone in frailty, for body weight gain, muscle mass gain, prevention of cachexia and for the treatment of chronic fatigue syndromes. Capromorelin [Entyce™ (Aratana Therapeutics, Leawood, KS, USA)] is the only FDA (Food and Drug Administration) approved (May 2016) drug used for stimulating appetite in dogs and was marketed in the fall of 2017. In 2020, USFDA approved Capromorelin [Elura™ (Elanco US Inc.)] for the management of weight loss in chronic kidney disease of cats. This article reviews the discovery of the ghrelin receptor agonist capromorelin, its efficacy, safety, clinical applications and aims to delineate its further scope of use in veterinary practice.

Is there a right time for dairy Alpine goat kid weaning: How does the weaning age of dairy Alpine goat kids affect their growth and behavior?

In dairy goat kids, weaning is often associated with poor growth leading to a decline in welfare and performance; however, little is known about optimal weaning practices. This study aimed to determine the optimal weaning age for dairy goat kids to maximize outcome measures of welfare related to growth, feed intake, and behavior. Thirty-six newborn female Alpine kids were blocked by weight and birth date, paired with a similar male companion and randomly allocated to one of the three weaning age treatments: 6 (6W), 8 (8W), and 10 wk (10W). Kids had ad libitum access to acidified milk replacer refilled twice daily, concentrates, hay, and water. Milk consumption was measured daily, and concentrate consumption, weekly. Ten behaviors were live observed on days -8, -4, 0, 6, and 12 relative to weaning (i.e., weaning day = 0). Kruskal-Wallis tests were used to assess differences from baseline between the 6W, 8W, and 10W treatments. Post hoc analysis using the Dwass, Steel, Critchlow-Fligner (DSCF) multiple comparison analysis was used to evaluate pairwise treatment differences based on two-sample Wilcoxon comparisons. Kids weaned at 10 wk had the greatest increase compared to baseline in concentrate consumption (P = 0.0160), and greatest decrease compared to baseline in vocalization (P = 0.0008) while both 8- and 10- wk kid's groups had the greatest increase compared to baseline in self-grooming time (P < 0.0001), and cross-sucking time (P = 0.0006). Kids weaned at 6 wk of age were found to have the smallest increase compared to baseline in concentrate consumption (P = 0.0160) and self-grooming time (P < 0.0001), and the greatest increase compared to baseline in allogrooming time (P = 0.0032) and in redirected behaviors aimed towards the environment (biting and licking time [P = 0.0173]; displacement at the nipple frequency [P = 0.0236]). No negative impact of weaning on growth of either group was identified. Overall, our results tend towards a higher degree of discomfort behaviors (allogrooming, biting/licking, displacement, and vocalizations) in kids weaned earlier compared to later weaning, while kids weaned later showed higher levels of positive behaviors (lying time and self-grooming).

Developmental changes of nutrient digestion in young lambs are influenced by weaning and associated with intestinal microbiota

Understanding the effects of weaning on the changes of digestive function could help to design efficient intervention strategies for promoting the development of the lamb during the early stages of life. In this study, 24 lambs were divided into two groups (control group, lambs were not weaned; and weaning group, lambs were weaned at 21 days of age). The growth, nutrient digestion, gastrointestinal enzyme activity, plasma biochemical indicators, and intestinal microbiota at 7-49 days were determined, as well as the impact of early weaning. The nutrient digestion changed rapidly with age, especially at 14-28 days (p < 0.05). Weaning reduced the dry matter (DM), crude protein (CP), and ether extract (EE) intake and digestion, but increased the starch, neutral detergent fiber (NDF), and acid detergent fiber (ADF) intake and digestion (p < 0.05). Weaning did not affect the overall jejunal microbiota (p > 0.05), but affected the relative abundance of certain bacteria taxa (p < 0.05). Lactic acid-producing bacteria, such as Olsenella, Bacillus, Sharpea, and Bifidobacterium are closely related to CP or EE digestion and growth performance (p < 0.05). In summary, we delineated the pattern of nutrient digestion and intestinal microbiota development in young lambs, and the impact of early weaning.