Gastrointestinal distribution of chicken gastrin-cholecystokinin family transcript expression and response to short-term nutritive state

Dietary supplementation of water extract of Eucommia ulmoides bark improved caecal microbiota and parameters of health in white-feathered broilers

Eucommia ulmoides has been used as a food and medicine homologue for a long time in China. We hypothesize that Eucommia ulmoides achieves its health-promoting effects via altering gut microbiota. Here, we investigated the effects of water extract of Eucommia ulmoides bark on caecal microbiota and growth performance, antioxidant activity, and immunity in white-feathered broilers treated for 42 days. A total of 108 one-day-old Cobb white-feathered broilers were randomly assigned to three treatment groups: control diet, 0.75% Eucommia ulmoides diet (EU Ⅰ) and 1.5% Eucommia ulmoides diet (EU Ⅱ). The results showed that EU Ⅱ treatment improved average body weight (ABW), thigh muscle quality and total length of intestines, and decreased the serum total triglycerides and total cholesterol (TC) (p < 0.05). Eucommia ulmoides supplementation increased serum superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), total antioxidant activities and content of immunoglobulins, and reduced levels of malondialdehyde and tumour necrosis factor-α (TNF-α) (p < 0.05). Moreover, the supplementation increased the diversity of caecal microbiota and reduced the pathogenic genera Escherichia Shigella and Helicobacter. The genera Ochrobactrum, Odoribater, Klebsiella, Enterobacter, Georgenia and Bifidobacterium were positively associated with the ABW, total intestinal length, serum levels of GSH-Px, SOD and immunoglobulins (p < 0.001) and negatively associated with the TC and TNF-α (p < 0.01), suggesting an association of the changes of gut microbiota and improvement of broiler health. Meanwhile, Eucommia ulmoides supplementation enriched the Kyoto Encyclopedia of Genes and Genomes pathway of exocrine secretion from the pancreas, circadian entrainment and inhibited lipopolysaccharide biosynthesis. In conclusion, Eucommia ulmoides water extract can be used as a feed additive to improve poultry industry production.

Therapeutic massage/Tuina for treatment of functional dyspepsia: a systematic review and meta-analysis of randomized controlled trials

PURPOSE

A systematic review of randomized controlled trials (RCTs) was conducted to assess the potential effect of therapeutic massage/Tuina on functional dyspepsia (FD) patients.

METHOD

Twelve databases and three clinical trial registries were searched until December 2021, for RCTs that compared Tuina combined with or without conventional therapy versus conventional therapy in FD. We assessed the methodological quality of included trials by the Cochrane Risk of Bias tool, and graded the quality of the evidence. The data were presented as risk ratio (RR) or mean difference (MD) respectively with their 95% confidence interval (CI).

RESULTS

In total, 14 RCTs with 1128 FD participants were included. Compared with conventional therapy, Tuina showed significant beneficial effects on improving overall symptom (RR = 1.12, 95% CI 1.06 to 1.19, low certainty evidence), and early satiation (MD -0.44 scores, 95% CI -0.72 to -0.16, very low certainty evidence). Compared with conventional therapy, Tuina plus conventional therapy also significantly improved overall symptom (RR = 1.14, 95% CI 1.06-1.23, low certainty evidence), quality of life (MD 10.44 scores, 95% CI 7.65-13.23, low certainty evidence), and epigastric pain (MD -0.76 scores, 95% CI -1.11 to -0.41, low certainty evidence). No adverse events related to Tuina and cost-effectiveness were reported.

CONCLUSION

Low certainty evidence showed that Tuina significantly improved overall symptom of FD participants compared with conventional therapy. Low certainty evidence showed that Tuina plus conventional therapy obviously improved overall symptom and quality of life of FD participants compared with conventional therapy.

Cholecystokinin (CCK) and its receptors (CCK1R and CCK2R) in chickens: functional analysis and tissue expression

Cholecystokinin (CCK) is widely distributed in the gastrointestinal tract and central nervous system, regulating a range of physiological functions by activating its receptors (CCK1R and CCK2R). Compared to those in mammals, the CCK gene and its receptors have already been cloned in various birds, such as chickens. However, knowledge regarding their functionality and tissue expression is limited. In this study, we examined the expression of CCK and its 2 receptors in chicken tissues. In addition, the functionality of the 2 receptors was investigated. Using 3 cell-based luciferase reporter systems and western blots, we demonstrated that chicken (c-) CCK1R could be potently activated by cCCK-8S but not cCCK-4, whereas cCCK2R could be activated by cCCK-8S and cCCK-4 with similar efficiency. Using RNA-sequencing, we revealed that cCCK is abundantly expressed in the testis, ileum, and several brain regions (cerebrum, midbrain, cerebellum, hindbrain, and hypothalamus). The abundant expression of CCK in the hypothalamus was further supported by immunofluorescence. In addition, cCCK1R is highly expressed in the pancreas and moderately expressed in various intestinal regions (ileum, cecum, and rectum) and the pituitary gland, whereas cCCK2R expression is primarily restricted to the brain. Our data reveal the differential specificities of CCK receptors for various CCK peptides. In combination with the differential tissue distribution of CCK and its receptors, the present study helps to understanding the physiological functions of CCK/CCKRs in birds.

The expression of the gastrin/cholecystokinin (GAST/CCK) family and their receptors (CCKAR/CCKBR) in the chicken changes in response to quantitative restriction and reveals a functional role of CCK in the crop

Gastrin and cholecystokinin peptides bind a common G-protein coupled receptor, cholecystokinin receptor B (CCKBR) whilst cholecystokinin receptor A (CCKAR) is preferentially bound by CCK. Gastrin and cholecystokinin mediate signalling from the gastrointestinal tract to regulate appetite and digestive function. In this study, expression of the cholecystokinin/gastrin family and distribution of their receptors expression was measured to understand the target organs for the peptides and how expression responds to changes in food intake. We confirmed the restricted expression of gastrin in the antrum and the abundant expression of cholecystokinin in the hypothalamus. The expression of gastrin in the antrum was significantly elevated in broiler breeders when released from feed restriction. CCKBR was most abundant in the hypothalamus and proventriculus. CCKAR was most abundant in the pancreas and crop, more than tenfold greater than the gastrointestinal tract. Cholecystokinin expression in the pancreas increased after removal of food restriction. CCKAR in the gastrointestinal tract peaks around the distal ileum, distal to the peak of cholecystokinin expression. There was virtually no cholecystokinin expression in the caecum but CCKAR expression was high. The CCKAR expression in the crop was unexpected, supporting a role of cholecystokinin in mediating crop emptying which was supported by the observation of in-vitro contraction after cholecystokinin administration. The response to changes in food intake and the expression pattern of the cholecystokinin/gastrin family and their receptors will stimulate and inform new hypotheses on their role in growth in poultry.

Seasonal differences in hypothalamic thyroid-stimulating hormone β, gonadotropin-releasing hormone-I and deiodinase expression between migrant and resident subspecies of white-crowned sparrow (Zonotrichia leucophrys)

Across taxa, the seasonal transition between non-breeding and breeding states is controlled by localised thyroid hormone signalling in the deep brain via reciprocal switching of deiodinase enzyme expression from type 3 (DIO3) to type 2 (DIO2). This reciprocal switch is considered to be mediated by increasing thyroid-stimulating hormone β (TSHβ) release from the pars tuberalis, which occurs in response to a change in photoperiod. Although well characterised in a handful of model organisms in controlled laboratory settings, this pathway remains largely unexplored in free-living animals under natural environmental conditions. In this comparative gene expression study, we investigated hypothalamic thyroid hormone signalling in two seasonally breeding subspecies of white-crowned sparrow (Zonotrichia leucophrys), across the entirety of their annual cycles. The migratory Gambel's (Z. l. gambelii) and resident Nuttall's (Z. l. nuttalii) subspecies differ with respect to timing of reproduction, as well as life history stage and migratory strategies. Although DIO3 mRNA expression was elevated and DIO2 mRNA expression was reduced in the wintering period in both subspecies, DIO2 peaked in both subspecies prior to the onset of reproduction. However, there was differential timing between subspecies in peak DIO2 expression. Intriguingly, seasonal modulation of TSHβ mRNA was only observed in migrants, where expression was elevated at the start of breeding, consistent with observations from other highly photoperiodic species. There was no correlation between TSHβ, DIO2 and gonadotropin-releasing hormone-I mRNA or reproductive metrics in residents. Based on these observed differences, we discuss potential implications for our understanding of how changes in medial basal hypothalamic gene expression mediates initiation of seasonal reproduction.

Effects of fasting and re-feeding on the expression of CCK, PYY, hypothalamic neuropeptides, and IGF-related genes in layer and broiler chicks

Cholecystokinin (CCK) and peptide YY (PYY) have been investigated as gut hormones that send satiation signals to the brain in mammals. There is evidence that chicken PYY mRNA expression was the highest in the pancreas compared to other tissues. We recently suggested that insulin-like growth factor (IGF)-1 and its binding proteins (IGFBPs) may be involved in the appetite regulation system in chicks. In the present study, in order to evaluate the possible roles of CCK, PYY, and IGF-related proteins in the appetite regulation system in chicks, we analyzed changes in the mRNA levels of these genes in response to fasting and re-feeding in layer and hyperphagic broiler chicks. In layer chicks, 12 h of fasting reduced the mRNA levels of intestinal CCK, PYY, Y2 receptor, and pancreatic PYY, and these changes were reversed by 12 h of re-feeding. On the other hand, in broiler chicks 12 h of fasting reduced the mRNA levels of intestinal PYY and Y2 receptor, but not intestinal CCK and pancreatic PYY, and these changes were reversed by 12 h of re-feeding. Hypothalamic NPY mRNA significantly increased by 12 h of fasting in both chicks, and these changes were reversed by re-feeding. Also, 12 h of fasting significantly increased the mRNA levels of hypothalamic agouti-related protein and reduced the mRNA levels of hepatic IGF-1 only in broiler chicks, and 12 h of re-feeding did not change these. IGFBP-1 and -2 mRNA levels were markedly increased by 12 h of fasting in both chicks, and these changes were reversed by re-feeding. IGFBP-3 mRNA levels were increased by 12 h of fasting only in layer chicks, while re-feeding reduced the mRNA levels of IGFBP-3 in both types of chicks. These results suggest that several peripheral hormones, such as pancreatic PYY and intestinal CCK, may not play important roles in the regulation of food intake in broiler chicks.

Effects of zinc oxide nanoparticles on regulatory appetite and heat stress protein genes in broiler chickens subjected to heat stress

This study was conducted to explore the effect of the zinc oxide nanoparticles (ZnONPs) supplement on the regulatory appetite and heat stress (HS) genes in broiler chickens raised under high or normal ambient temperatures. In this study, 240 one-day-old male broiler chicks (Cobb 500) were randomly assigned to 48 battery cages. From day 1, these 48 cages were randomly subjected to four different treatment strategies: Control (wherein, their basal diet included 60 mg/kg of ZnO), ZNONPs 40 (wherein basal diet included 40 mg/kg of ZnONPs), ZnONPs 60 (basal diet included 60 mg/kg of ZnONPs), and ZnONPs 100 (basal diet included 100 mg/kg of ZnONPs). Thereafter, from day 22 to 42, the chickens from each dietary treatment group were subjected to different temperature stresses either normal (23 ± 1 °C constant) or HS (34 ± 1 °C for 6 h/d), which divided them into eight different treatment groups. Our findings revealed that dietary ZnONPs altered the gene expression of cholecystokinin (ileum), heat stress proteins (HSP) 70 (jejunum and ileum), and HSP 90 (duodenum, jejunum, and ileum). The gene expression of ghrelin was affected by the interaction between the ZnONPs concentration and temperature in the duodenum and stomach. More studies are required to elucidate its complex physiological and biochemical functions of the regulation of gene expression within the intestine in heat-stressed broiler chickens.

The gut-brain axis in vertebrates: implications for food intake regulation

The gut and brain are constantly communicating and influencing each other through neural, endocrine and immune signals in an interaction referred to as the gut-brain axis. Within this communication system, the gastrointestinal tract, including the gut microbiota, sends information on energy status to the brain, which, after integrating these and other inputs, transmits feedback to the gastrointestinal tract. This allows the regulation of food intake and other physiological processes occurring in the gastrointestinal tract, including motility, secretion, digestion and absorption. Although extensive literature is available on the mechanisms governing the communication between the gut and the brain in mammals, studies on this axis in other vertebrates are scarce and often limited to a single species, which may not be representative for obtaining conclusions for an entire group. This Review aims to compile the available information on the gut-brain axis in birds, reptiles, amphibians and fish, with a special focus on its involvement in food intake regulation and, to a lesser extent, in digestive processes. Additionally, we will identify gaps of knowledge that need to be filled in order to better understand the functioning and physiological significance of such an axis in non-mammalian vertebrates.

Transcriptome analysis of the uterus of hens laying eggs differing in cuticle deposition

Background

Avian eggs have a proteinaceous cuticle. The quantity of cuticle varies and the deposition of a good cuticle in the uterus (Shell-gland) prevents transmission of bacteria to the egg contents.

Results

To understand cuticle deposition, uterus transcriptomes were compared between hens with i) naturally good and poor cuticle and, ii) where manipulation of the hypothalamo-pituitary-gonadal-oviduct axis produced eggs with or without cuticle. The highest expressed genes encoded eggshell matrix and cuticle proteins, e.g. MEPE (OC-116), BPIFB3 (OVX-36), RARRES1 (OVX-32), WAP (OVX-25), and genes for mitochondrial oxidative phosphorylation, active transport and energy metabolism. Expression of a number of these genes differed between hens laying eggs with or without cuticle. There was also a high expression of clock genes. PER2, CRY2, CRY1, CLOCK and BMAL1 were differentially expressed when cuticle deposition was prevented, and they also changed throughout the egg formation cycle. This suggests an endogenous clock in the uterus may be a component of cuticle deposition control. Cuticle proteins are glycosylated and glycosaminoglycan binding genes had a lower expression when cuticle proteins were deposited on the egg. The immediate early genes, JUN and FOS, were expressed less when the cuticle had not been deposited and changed over the egg formation cycle, suggesting they are important in oviposition and cuticle deposition. The uterus transcriptome of hens with good and poor cuticle deposition did not differ.

Conclusions

We have gained insights into the factors that can affect the production of the cuticle especially clock genes and immediate early genes. We have demonstrated that these genes change their expression over the period of eggshell formation supporting their importance. The lack of differences in expression between the uterus of hens laying eggs with the best and worse cuticle suggest the genetic basis of the trait may lie outside the oviduct.

Chicken Intestinal L Cells and Glucagon-like Peptide-1 Secretion

Many types of endocrine cells have been identified in the gastroenteropancreatic system of vertebrates, which have subsequently been named with alphabet (s). L cells which secrete the glucagon-like peptide (GLP)-1 are scattered in the intestinal epithelium. This review discusses the morphological features of chicken L cells and GLP-1 secretion from intestinal L cells. L cells, identified using GLP-1 immunohistochemistry, are open-type endocrine cells that are distributed in the jejunum and ileum of chickens. GLP-1 co-localizes with GLP-2 and neurotensin in the same cells of the chicken ileum. Intestinal L cells secrete GLP-1 in response to food ingestion. Proteins and amino acids, such as lysine and methionine, in the diet trigger GLP-1 secretion from the chicken intestinal L cells. The receptor that specifically binds chicken GLP-1 is expressed in pancreatic D cells, implying that the physiological functions of chicken GLP-1 differ from its functions as an incretin in mammals.

Tissue-specific expression of 11β-HSD and its effects on plasma corticosterone during the stress response

The hypothalamic-pituitary-adrenal (HPA) axis is under complex regulatory control at multiple levels. Enzymatic regulation plays an important role in both circulating levels of glucocorticoids and target tissue exposure. Three key enzyme pathways are responsible for the immediate control of glucocorticoids. De novo synthesis of glucocorticoid from cholesterol involves a multistep enzymatic cascade. This cascade terminates with 11β-hydroxylase, responsible for the final conversion of 11-deoxy precursors into active glucocorticoids. Additionally, 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) controls regeneration of glucocorticoids from inactive metabolites, providing a secondary source of active glucocorticoids. Localized inactivation of glucocorticoids is under the control of Type 2 11β-HSD (11β-HSD2). The function of these enzymes is largely unexplored in wild species, particularly songbirds. Here, we investigated the contribution of both clearance and generation of glucocorticoids to regulation of the hormonal stress response via the use of pharmacological antagonists. Additionally, we mapped 11β-HSD gene expression. We found 11β-HSD1 primarily in liver, kidney and adrenal glands, although it was detectable across all tissue types. 11β-HSD2 was predominately expressed in the adrenal glands and kidney with moderate gonadal and liver expression. Inhibition of glucocorticoid generation by metyrapone was found to decrease levels peripherally, while both peripheral and central administration of the 11β-HSD2 inhibitor DETC resulted in elevated concentrations of corticosterone. These data suggest that during the stress response, peripheral antagonism of the 11β-HSD system has a greater impact on circulating glucocorticoid levels than central control. Further studies should aim to elucidate the respective roles of the 11β-HSD and 11β-hydroxylase enzymes.

Enteroendocrine profile of α-transducin and α-gustducin immunoreactive cells in the chicken (Gallus domesticus) gastrointestinal tract

The enteroendocrine profile and distribution patterns of the taste signaling molecules, α-gustducin (Gαgust) and α-transducin (Gαtran) protein subunits, were studied in the gastrointestinal (GI) tract of the chicken (Gallus domesticus) using double labeling immunohistochemistry. Gαtran or Gαgust immunoreactivity was observed in enteroendocrine cells (EEC) expressing different peptides throughout the entire GI tract with different density. In the proventriculus tubular gland, Gαtran or Gαgust/gastrin (GAS) immunoreactive (-IR) cells were more abundant than Gαtran/or Gαgust containing glucagon-like peptide-1 (GLP-1) or peptide YY (PYY), whereas only few Gαtran or Gαgust cells co-stored ghrelin (GHR) or 5-hydroxytryptamine (5-HT). In the pyloric mucosa, many Gαtran or Gαgust-IR cells co-expressed GAS or GHR, with less Gαtran or Gαgust cells containing GLP-1, PYY, or 5-HT. In the small intestine, a considerable subset of Gαtran or Gαgust-IR cells co-expressed 5-HT in the villi of the duodenum and ileum, PYY in the villi of the jejunum, CCK or GLP-1 in the villi of the ileum, and GHR in the duodenum crypts. In the large intestine, many Gαtran or Gαgust-IR cells contained 5-HT or GLP-1 in the villi of the rectum, whereas some Gαtran/Gαgust-IR cells co-expressed PYY- or CCK-, and few Gαtran/Gαgust-IR cells were positive for GHR-IR. In the cecum, several Gαtran or Gαgust-IR cells were IR for 5-HT. Finally, many Gαtran/Gαgust cells containing 5-HT were observed in the villi and crypts of the cloaca, whereas there were few Gαtran or Gαgust/CCK-IR cells. The demonstration that Gα-subunits are expressed in the chicken GI enteroendocrine system supports the involvement of taste signaling machinery in the chicken chemosensing processes.