Detection of single nucleotide polymorphism in HTR4 and its relationship with growth traits in sheep.

In this study, a single nucleotide polymorphism of HTR4 (hydroxytryptamine receptor 4) was detected using DNA sequencing and KASPar (Kompetitive Allele-Specific PCR) technique with the aim of analyzing its effect on growth traits in 1102 sheep. A synonymous mutation g.101220 C > T located on the fifth intron of the ovis HTR4 gene was detected, and association analysis showed that this mutation was significantly associated with growth traits in sheep (p ＜.05), with TT genotypes having significantly lower body weight, height, length and chest circumference than TC and CC genotypes. It showed that the polymorphism of this locus was significantly associated with growth traits in sheep. In addition, qRT-PCR results showed that HTR4 was expressed in different tissues of sheep. It is highly expressed in the liver, spleen and duodenum. As important metabolic, immune and digestive absorption organs in animals, the above tissues can regulate the excitability of intestinal smooth muscle by participating in the body metabolism and nutrient metabolism of sheep, so that sheep can show better growth characteristics. In conclusion, the polymorphic locus identified in HTR4 gene can be used as candidate molecular marker in sheep breeding.

The GG genotype of the serotonin 4 receptor genetic polymorphism, rs1345697, is associated with lower remission rates after antidepressant treatment: Findings from the METADAP cohort.

BACKGROUND: Pharmacological studies have yielded valuable insights into the role of the serotonin 4 receptor (HTR4) in major depressive episodes (MDE) and response to antidepressant drugs (AD). A genetic association has been shown between HTR4 and susceptibility to mood disorders. Our study aims at assessing the association between the HTR4 genetic polymorphism, rs1345697, and improvement in depressive symptoms and remission after antidepressant treatment in MDE patients. METHODS: 492 depressed patients from the METADAP cohort were treated prospectively for 6 months with ADs. The clinical outcomes according to HTR4 rs1345697 were compared after 1 (M1), 3 (M3), and 6 (M6) months of treatment. Mixed-effects logistic regression and adjusted linear models assessed the association between rs1345697 and 17-item Hamilton Depression Rating Scale (HDRS) score improvement and response/remission. RESULTS: Over the 6 months of treatment, mixed-effects regressions showed lower improvements in HDRS scores (Coefficient=1.52; Confident Interval (CI) 95% [0.37-2.67]; p = 0.009) and lower remission rates (Odds Ratio=2.0; CI95% [1.0-4.1]; p = 0.05) in GG homozygous patients as compared to allele A carriers. LIMITATIONS: The major limitations of our study are the uncertainty of the rs1345697 effect on HTR4 function, the substantial drop-out rate, and the fact that analysis is not based on randomization between polymorphism groups. CONCLUSIONS: In our study, patients who were homozygous carriers of the variant G of the HTR4 rs1345697 had lower depressive symptoms improvement and 2-fold lower remission rates after antidepressant treatment as compared to allele A carriers. Randomization study should be done to confirm these results.

Cataloging recent advances in epigenetic alterations in major mental disorders and autism.

During the last two decades, diverse epigenetic modifications including DNA methylation, histone modifications, RNA editing and miRNA dysregulation have been associated with psychiatric disorders. A few years ago, in a review we outlined the most common epigenetic alterations in major psychiatric disorders (e.g., aberrant DNA methylation of DTNBP1, HTR2A, RELN, MB-COMT and PPP3CC, and increased expression of miR-34a and miR-181b). Recent follow-up studies have uncovered other DNA methylation aberrations affecting several genes in mental disorders, in addition to dysregulation of many miRNAs. Here, we provide an update on new epigenetic findings and highlight potential origin of the diversity and inconsistencies, focusing on drug effects, tissue/cell specificity of epigenetic landscape and discuss shortcomings of the current diagnostic criteria in mental disorders.

Intracellular GPCRs Play Key Roles in Synaptic Plasticity.

The trillions of synaptic connections within the human brain are shaped by experience and neuronal activity, both of which underlie synaptic plasticity and ultimately learning and memory. G protein-coupled receptors (GPCRs) play key roles in synaptic plasticity by strengthening or weakening synapses and/or shaping dendritic spines. While most studies of synaptic plasticity have focused on cell surface receptors and their downstream signaling partners, emerging data point to a critical new role for the very same receptors to signal from inside the cell. Intracellular receptors have been localized to the nucleus, endoplasmic reticulum, lysosome, and mitochondria. From these intracellular positions, such receptors may couple to different signaling systems, display unique desensitization patterns, and/or show distinct patterns of subcellular distribution. Intracellular GPCRs can be activated at the cell surface, endocytosed, and transported to an intracellular site or simply activated in situ by de novo ligand synthesis, diffusion of permeable ligands, or active transport of non-permeable ligands. Current findings reinforce the notion that intracellular GPCRs play a dynamic role in synaptic plasticity and learning and memory. As new intracellular GPCR roles are defined, the need to selectively tailor agonists and/or antagonists to both intracellular and cell surface receptors may lead to the development of more effective therapeutic tools.

Correlated gene expression encoding serotonin (5-HT) receptor 4 and 5-HT transporter in proximal colonic segments of mice across different colonization states and sexes.

The production and handling of serotonin (5-HT) is an important determinant of colonic motility and has been reported to be altered in gastrointestinal (GI) disorders such as irritable bowel syndrome (IBS). Recent studies suggest that the intestinal microbiota and sex of the host can influence expression of genes involved in 5-HT biosynthesis and signaling. While expression of genes in serotonergic pathways has been shown to be variable, it remains unclear whether genes within this pathway are coregulated. As a first step in that direction, we investigated potential correlations in relative mRNA expression of serotonergic genes, in the proximal colon isolated from male and female mice in different states of microbial association: germ-free (GF), humanized (ex-germ-free colonized with human gut microbiota, HM), and conventionally raised (CR) mice. Among the 10 pairwise comparisons conducted between five serotonergic transcripts, Tph1, Chga, Maoa, Slc6a4, and Htr4, we found a strong, positive correlation between colonic expression of Slc6a4 and Htr4 across different colonization states and sexes. We also identified a positive correlation between the expression of Tph1 and Chga; however, there were no correlations observed between any other tested pair of 5-HT-related transcripts. These data suggest that correlated expression of Slc6a4 and Htr4 likely involves coregulation of genes located on different chromosomes which modulate serotonergic activity in the gut. Further work will need to be done to understand the pathways and cell types responsible for this correlated expression, given the important role of 5-HT in gastrointestinal physiology.

Mechanism of aqueous fructus aurantii immaturus extracts in neuroplexus of cathartic colons.

AIM: To examine the effect of aqueous fructus aurantii immaturus (FAI) extracts on the intestinal plexus of cathartic colons. METHODS: Cathartic colons were induced in rats with dahuang, a laxative used in traditional Chinese medicine. Once the model was established (after approximately 12 wk), rats were administered mosapride (1.54 mg/kg) or various doses of aqueous FAI extracts (1-4 g/kg) for 14 d. Transit function was assessed using an ink propulsion test. Rats were then sacrificed, and the ultramicrostructure of colonic tissue was examined using transmission electron microscopy. The expression of the 5-hydroxytryptamine receptor 4 (5-HTR4) and neurofilament-H was assessed in colon tissues using real-time PCR, Western blot, and immunohistochemistry. RESULTS: Mosapride and high dose (4 g/kg) of aqueous FAI extracts significantly improved the bowel movement in cathartic colons compared to untreated model colons as measured by the intestinal transit rate (70.06 ± 7.25 and 72.02 ± 8.74, respectively, vs 64.12 ± 5.19; P < 0.05 for both). Compared to controls, the ultramicrostructure of cathartic colons showed signs of neural degeneration. Treatment with mosapride and aqueous FAI extracts resulted in recovery of ultrastructural pathology. Treatment with mosapride alone upregulated the gene and protein expression of 5-HTR4 compared to untreated controls (P < 0.05 for both). Treatment with aqueous FAI extracts (≥ 2 g/kg) increased 5-HTR4 mRNA levels (P < 0.05), but no change in protein level was observed by Western blot or immunohistochemistry. The mRNA and protein levels of neurofilament-H were significantly increased with mosapride and ≥ 2 g/kg aqueous FAI extracts compared to controls (P < 0.05 for all). CONCLUSION: Aqueous FAI extracts and mosapride strengthen bowel movement in cathartic colons via increasing the expression of 5-HTR4 and neurofilament-H.

Anhedonia was associated with the dysregulation of hippocampal HTR4 and microRNA Let-7a in rats.

OBJECTIVE: Depression is a serious mental illness. However, the molecular mechanisms responsible for the development of depression remain unknown. METHODS: In this study, animal models of depression were established using maternal deprivation (MD) and chronic unpredictable stress (CUPS). Behavioral performance of rats was monitored by open field test, forced swim test, and sucrose consumption test. The expression of serotonin receptor-4 (Htr4) mRNA and Let-7a microRNA was detected by real-time PCR, while Htr4 protein level was measured by Western blot. RESULTS: In the open field test, rats subjected to MD and CUPS exhibited significant decreases in vertical activity. CUPS rats spent less time in the central area and excreted more fecal pellets than MD and control rats. In the forced swim and sucrose consumption tests, CUPS and MD rats exhibited significantly longer floating time and consumed less sucrose than control rats. MD rats exhibited significantly shorter floating time and consumed less sucrose than CUPS rats. MD rats showed significantly lower Htr4 mRNA and protein expression and significantly higher Let-7a level in the hippocampus than control rats. Htr4 mRNA and protein expression negatively correlated with Let-7a expression. Htr4 mRNA expression positively correlated with sucrose preference rate, while Let-7a expression negatively correlated with the sucrose preference rate. CONCLUSION: Anhedonia, not despair or a decline in exploratory interest, may be associated with upregulation of Let-7a and downregulation of Htr4 expression in the hippocampus. The hippocampal Htr4 level may be regulated by Let-7a in rats.

Association of five genetic variants with chronic obstructive pulmonary disease susceptibility and spirometric phenotypes in a Chinese Han population.

BACKGROUND AND OBJECTIVE: Recent genome-wide association studies have shown associations between variants at five loci (TNS1, GSTCD, HTR4, AGER and THSD4) and chronic obstructive pulmonary disease (COPD) or lung function. However, their association with COPD has not been proven in Chinese Han population, nor have COPD-related phenotypes been studied. The objective of this study was to look for associations between five single nucleotide polymorphisms (SNP) in these novel candidate genes and COPD susceptibility or lung function in a Chinese Han population. METHODS: Allele and genotype data on 680 COPD patients and 687 healthy controls for sentinel SNP in these five loci were investigated. Allele frequencies and genotype distributions were compared between cases and controls, and odds ratios were calculated. Potential relationships between these SNP and COPD-related lung function were assessed. RESULTS: No significant associations were found between any of the SNP and COPD in cases and controls. The SNP (rs3995090) in HTR4 was associated with COPD (adjusted P = 0.022) in never-smokers, and the SNP (rs2070600) in AGER was associated with forced expiratory volume in 1 s (FEV1 %) predicted (ß = -0.066, adjusted P = 0.016) and FEV1 /forced vital capacity (ß = -0.071, adjusted P = 0.009) in all subjects. CONCLUSIONS: The variant at HTR4 was associated with COPD in never-smokers, and the SNP in AGER was associated with pulmonary function in a Chinese Han population.

The dysregulation of hippocampal serotonin receptor 4 and let-7a were associated with dual stress-induced depression in rats / 中华行为医学与脑科学杂志

Objective To study the effect of dual stress on the behaviors and the expression of hippocampal let-7a and serotonin receptor 4(HTR4) in rats.Methods Newborn SD rats were randomly divided into dual stress group (DS,n=6) and control group (C,n=6).The DS rats were deprived of the mother care 6 hours per day from postnatal day 1 to 14 and then were exposed to chronic mild stress for 21 days from 10 weeks old,while the rats from C group received no experimental handle but husbandry care.Open field test,forced swimmiug test and sucrose consumption test were conducted to evaluate rats' depression-like behaviors at the age of thirteen weeks.The let-7a level in hippocampus was detected by real-time Polymerase Chain Reaction and the HTR4 protein level was measured by Western Blotting.Results In the open filed test,the rearing times of DS rats was shorter than that of C group((7.50±2.35) vs (19.00±5.73),P＜0.05).In the forced swimming test,the floating time of DS rats was longer than that of C group ((110.17 ± 1.72)s vs (70.33± 1.16)s,P＜ 0.05).In the sucrose c onsumption test,DS rats consumed less sucrose than rats from C group did((0.80±0.73) vs (0.52±0.26),P＜ 0.05).The protein level of hippocampal HTR-4 in DS group was lower than that of C group((1.44±0.38) vs (0.46±0.29),P＜0.01).The let-7a level in DS group was higher than that of C group((0.04±0.01) vs (1.58±0.27),P＜0.01).The Pearson correlation analysis revealed that the sucrose preference rate of rats were negatively and positively correlated with hippocampal let-7a and HTR4 level respectively(r=-0.653,P＜0.05; r=0.774,P＜0.01),and hippocampal let-7a level showed negative association with HTR4 protein level (r=-0.803,P＜0.01).Conclusion Dual stress can induce the depressive behaviors of rats and affect the expression of let-7a and HTR4 in hippocampus.Hippocampal HTR4 and let-7a might be involved in determining individual ability to experience pleasure in rats;and hippocampal let-7a may be involved in the regulation of HTR4 gene expression in rats.