Olanzapine May Inhibit Colonic Motility Associated with the 5-HT Receptor and Myosin Light Chain Kinase

Alterations in descending brain-spinal pathways regulating colorectal motility in a rat model of Parkinson's disease

Patients with Parkinson's disease (PD) often have constipation. It is assumed that a disorder of the regulatory mechanism of colorectal motility by the central nervous system is involved in the constipation, but this remains unclear. The aim of this study was to investigate whether central neural pathways can modulate colorectal motility in a rat model of PD. PD model rats were generated by injection of 6-hydroxydopamine into a unilateral medial forebrain bundle and destruction of dopaminergic neurons in the substantia nigra. Colorectal motility was measured in vivo in anesthetized rats. Intraluminal administration of capsaicin, as a noxious stimulus, induced colorectal motility in sham-operated rats but not in PD rats. Intrathecally administered dopamine (DA) and serotonin (5-HT), which mediate the prokinetic effect of capsaicin, at the L6-S1 levels enhanced colorectal motility in PD rats similarly to that in sham-operated rats. In PD rats, capsaicin enhanced colorectal motility only when a GABAA receptor antagonist was preadministered into the lumbosacral spinal cord. Capsaicin-induced colorectal motility was abolished by intrathecal administration of a D2-like receptor antagonist but not by administration of 5-HT2 and 5-HT3 receptor antagonists. These findings demonstrate that the inhibitory GABAergic component becomes operative and the stimulatory serotonergic component is suppressed in PD rats. The alteration of the central regulatory mechanism of colorectal motility is thought to be related to the occurrence of constipation in PD patients. Our findings provide a new insight into the pathogenesis of defecation disorders observed in PD.NEW & NOTEWORTHY In a rat model of Parkinson's disease, the component of descending brain-spinal pathways that regulate colorectal motility through a mediation of the lumbosacral defecation center was altered from stimulatory serotonergic neurons to inhibitory GABAergic neurons. Our findings suggest that chronic constipation in Parkinson's disease patients may be associated with alterations in central regulatory mechanisms of colorectal motility. The plasticity in the descending pathway regulating colorectal motility may contribute to other disease-related defecation abnormalities.

Protective effect of L-pipecolic acid on constipation in C57BL/6 mice based on gut microbiome and serum metabolomic

BACKGROUND

Functional constipation (FC) in children affects their growth, development and quality of life. L-pipecolic acid (L-PA) was decreased in FC children based on gut microbiome and serum metabolomic. In this study, loperamide-induced constipation in mice was used to evaluate the effects of L-PA on constipated mice.

METHOD

26 FC and 28 healthy children were recruited. Stool samples and serum samples were subjected to 16S rDNA sequencing and ultra-performance liquid chromatography/quadrupole time of flight (UPLC-Q/TOF-MS) approach, respectively. A loperamide-induced mouse constipation model was developed, and all mice were randomly divided into control (Con), loperamide (Lop) and L-PA (Lop + L-PA) treatment groups (6 mice per group). The mice in the Lop + L-PA group were given L-PA (250 mg/kg, once a day) and loperamide; the Lop group was given loperamide for 1 week, and the Con group was given saline. The fecal parameters and intestinal motility of mice in each group were detected. serum 5-HT levels and colon 5-HT expression were detected by ELISA and immunohistochemistry, respectively; qRT-PCR was used to detect the expression of AQP3 and 5-HT4R mRNA in each group.

RESULTS

45 differential metabolites and 18 significantly different microbiota were found in FC children. The α and β diversity of gut microbiota in FC children was significantly reduced. Importantly, serum L-PA was significantly reduced in FC children. The KEGG pathway enrichment were mainly enriched in fatty acid biosynthesis, lysine degradation, and choline metabolism. L-PA was negatively associated with Ochrobactrum, and N6, N6, N6-trimethyl-l-lysine was positively associated with Phascolarcrobacterium. In addition, L-PA improved the fecal water content, intestinal transit rate, and increased the serum 5-HT levels in constipated mice. Moreover, L-PA increased the expression of 5-HT4R, reduced AQP3, and regulated constipation-associated genes.

CONCLUSIONS

Gut microbiota and serum metabolites were significantly altered in children with FC. The abundance of Phascolarctobacterium and Ochrobactrum and serum L-PA content were decreased in FC children. L-PA was found to alleviate the fecal water content, increase intestinal transit rate and the first black stool defecation time. L-PA improved constipation by increasing 5-HT and 5-HT4R expression while down-regulating AQP3 expression.

Stercoral Perforation in the Setting of Chronic Antipsychotic Use: A Case Report

Stercoral perforation is a rare form of colonic perforation with limited reports in the literature, accounting for less than 140 documented cases. This complication occurs due to increased intraluminal pressure created by fecal impaction, ultimately causing colonic ulceration and necrosis. It is most often seen in elderly or debilitated patients with chronic constipation. The long-term use of drugs or medications with side effects of chronic constipation such as opioids, antispasmodics, tricyclic antidepressants, and calcium channel blockers have been implicated in these cases. Here we present a case of stercoral perforation in a patient with short-term opioid use following an orthopedic procedure, but more likely complicated by long-term use of antipsychotics and antidepressants.

Probiotic coated with glycol chitosan/alginate relieves oxidative damage and gut dysmotility induced by oxytetracycline in zebrafish larvae

Probiotic-based therapy is a promising approach, which can positively modulate bacterial composition and maintain homeostasis. However, exogenous probiotics are easily destroyed by harsh conditions in vivo; thus, their application prospects have been severely limited. Specifically, oxytetracycline (OTC), a broad-spectrum antibiotic widely used in aquaculture, results in adverse intestinal environments, such as dysbacteriosis, oxidative damage, and gut dysmotility. Here, we describe a facile method to apply glycol chitosan/alginate as armor on the surface of probiotics to effectively protect them from the changed enteric environments induced by OTC. The results demonstrated that the coated Lacticaseibacillus rhamnosus GG (LGG) for only 2 h administration could significantly improve the colonization rate of LGG, and the relative abundance of Lacticaseibacillus can reach 80% in OTC-treated larvae intestines. We also explored the specific mechanisms of the coated LGG to diminish reactive oxygen species (ROS) generation and rescue gut dysmotility for OTC treatment, including enhancing the activity of antioxidative enzymes (CAT, SOD and GPx) and increasing 5-HT synthesis. The mitigation effect of the coated LGG for 2 h administration was comparable to that of uncoated LGG for 24 h administration. Encapsulation of LGG with polysaccharides provides a unique application example for generating useful bacterial therapeutics in harsh intestinal environments.

Lactobacillus rhamnosus GG normalizes gut dysmotility induced by environmental pollutants via affecting serotonin level in zebrafish larvae

Intestinal peristalsis is essential for gastrointestinal function, which could maintain the appropriate progression and digestion of food and reduce bacterial aggregation through mixing function. Even though certain ingredients of foodstuff are known to increase or decrease intestinal peristalsis, the role of environmental pollutants on intestinal peristalsis is relatively unknown. Therefore, the effects of four typical environmental pollutants (oxytetracycline, arsenic, polychlorinated biphenyls and chlorpyrifos) on intestinal peristalsis in the zebrafish model and then tested the recovery effect of the constipation-resistant probiotic. The results showed that 4-day environmental pollutants exposures on the zebrafish embryos at 1 day post fertilization clearly decreased the intestinal peristalsis through decreasing the serotonin (5-HT) production and down-regulating the expression of key genes involved in 5-HT synthesis. Pollutants-evoked change of gut motility could be normalized in the presence of Lactobacillus rhamnosus GG (LGG) via increasing 5-HT secretion. Exogenous 5-hydroxytryptophan (100 µg/L) could also rescue the dysfunction of gut motility in pollutants-treated zebrfish. The data identified that LGG normalized disorder of intestinal peristalsis induced by environmental pollutants through increasing 5-HT level. The stimulant effect of LGG on peristalsis may be associated with 5-HT system, which could provide references for the application of probiotics in regulation of gut dysmotility.

Localization of the Serotonin Transporter in the Dog Intestine and Comparison to the Rat and Human Intestines

Serotonin is crucial in gastrointestinal functions, including motility, sensitivity, secretion, and the inflammatory response. The serotonin transporter (SERT), responsible for serotonin reuptake and signaling termination, plays a prominent role in gastrointestinal physiology, representing a promising therapeutic target in digestive disorders. Serotonin transporter expression has been poorly investigated in veterinary medicine, under both healthy and pathological conditions, including canine chronic enteropathy, in which the serotonin metabolism seems to be altered. The aim of the present study was to determine the distribution of SERT immunoreactivity (SERT-IR) in the dog intestine and to compare the findings with those obtained in the rat and human intestines. Serotonin transporter-IR was observed in canine enterocytes, enteric neurons, lamina propria cells and the tunica muscularis. Data obtained in dogs were consistent with those obtained in rats and humans. Since the majority of the serotonin produced by the body is synthesized in the gastrointestinal tract, SERT-expressing cells may exert a role in the mechanism of serotonin reuptake.

Microbial Profiles of Patients With Antipsychotic-Related Constipation Treated With Electroacupuncture

Antipsychotic-related constipation (APRC) is one of the most common side effects of taking antipsychotic medication. APRC can seriously impact patient quality of life and is potentially fatal, though the efficacy of current APRC treatments is low for most patients. In this study, we conducted a controlled, pilot randomized, sham-electroacupuncture (SEA) study to assess the efficacy of electroacupuncture (EA) in patients with APRC. We used 16S rRNA gene sequencing to assess the microbial profiles of these patients and analyze how EA treatments affected their bacteria.

Methods: We treated 133 APRC patients with randomly assigned EA treatments or SEA treatments for 4 consecutive weeks, fully evaluating the patients 8 weeks after treatment. The participants, outcome assessors, and statistics were all blind to the EA and SEA treatments. Outcomes assessed included changes in spontaneous bowel movements (SBMs) and the frequency of rescue measures. We detected assessed the microbial diversity of stool specimens both before and after EA treatment using 16S rRNA gene sequencing.

Results: Both EA and SEA treatments reduced the need for constipation rescue measures and did not have serious side effects. EA treatments were better than SEA treatments at increasing SBMs and reducing rescue measures. The diversity of gut microbiota changed after EA treatment. LEfSe analysis indicated changes in the genus (belonging to phylum Proteobacteria) of gut microbiota in patients following EA treatment.

Conclusions: This study found that EA treatment is effective and safe for patients with APRC, and could be associated with changes in their microbial profiles. Further study, with larger sample sizes, is needed to explore the efficacy of EA intervention as a clinical treatment for APRC.

Trial Registration: ChiCTR, ChiCTR-ONC-17010842, http://www.chictr.org.cn/showproj.aspx?proj=18420.

Genetic Polymorphisms Associated With the Pharmacokinetics, Pharmacodynamics and Adverse Effects of Olanzapine, Aripiprazole and Risperidone

Olanzapine, aripiprazole and risperidone are atypical antipsychotics or neuroleptics widely used for schizophrenia treatment. They induce various adverse drug reactions depending on their mechanisms of action: metabolic effects, such as weight gain and alterations of glucose and lipid metabolism; hyperprolactinemia and extrapyramidal effects, such as tremor, akathisia, dystonia, anxiety and distress. In this review, we listed polymorphisms associated with individual response variability to olanzapine, aripiprazole and risperidone. Olanzapine is mainly metabolized by cytochrome P450 enzymes, CYP1A2 and CYP2D6, whereas aripiprazole and risperidone metabolism is mainly mediated by CYP2D6 and CYP3A4. Polymorphisms in these genes and other enzymes and transporters, such as enzymes from the uridine 5'-diphospho-glucuronosyltransferase (UGT) family and ATP-binding cassette sub-family B member 1 (ABCB1), are associated to differences in pharmacokinetics. The three antipsychotics act on dopamine and serotonin receptors, among others, and several studies found associations between polymorphisms in these genes and variations in the incidence of adverse effects and in the response to the drug. Since olanzapine is metabolized by CYP1A2, a lower starting dose should be considered in patients treated with fluvoxamine or other CYP1A2 inhibitors. Regarding aripiprazole, a reduced dose should be administered in CYP2D6 poor metabolizers (PMs). Additionally, a reduction to a quarter of the normal dose is recommended if the patient is treated with concomitant CYP3A4 inhibitors. Risperidone dosage should be reduced for CYP2D6 PMs and titrated for CYPD6 ultrarapid metabolizers (UMs). Moreover, risperidone dose should be evaluated when a CYP2D6, CYP3A4 or ABCB1 inhibitor is administered concomitantly.

Safety and cardiovascular effects of multiple-dose administration of aripiprazole and olanzapine in a randomised clinical trial

OBJECTIVE

To assess adverse events (AEs) and safety of aripiprazole (ARI) and olanzapine (OLA) treatment.

METHODS

Twenty-four healthy volunteers receiving five daily oral doses of 10 mg ARI and 5 mg OLA in a crossover clinical trial were genotyped for 46 polymorphisms in 14 genes by qPCR. Drug plasma concentrations were measured by high-performance liquid chromatography tandem mass spectrometry. Blood pressure (BP) and 12-lead electrocardiogram were measured in supine position. AEs were also recorded.

RESULTS

ARI decreased diastolic BP on the first day and decreased QTc on the third and fifth day. OLA had a systolic and diastolic BP, heart rate and QTc lowering effect on the first day. Polymorphisms in ADRA2A, COMT, DRD3 and HTR2A genes were significantly associated to these changes. The most frequent adverse drug reactions (ADRs) to ARI were somnolence, headache, insomnia, dizziness, restlessness, palpitations, akathisia and nausea while were somnolence, dizziness, asthenia, constipation, dry mouth, headache and nausea to OLA. Additionally, HTR2A, HTR2C, DRD2, DRD3, OPRM1, UGT1A1 and CYP1A2 polymorphisms had a role in the development of ADRs.

CONCLUSIONS

OLA induced more cardiovascular changes; however, more ADRs were registered to ARI. In addition, some polymorphisms may explain the difference in the incidence of these effects among subjects.

Dysbiosis contributes to chronic constipation development via regulation of serotonin transporter in the intestine

Chronic constipation is a prevalent functional gastrointestinal disorder accompanied with intestinal dysbiosis. However, causal relationship between dysbiosis and constipation remains poorly understood. Serotonin transporter (SERT) is a transmembrane transport protein which re-uptakes excessive 5-hydroxytryptamine (5-HT) from effective location to terminate its physiological effects and involves in regulating gastrointestinal motility. In this study, fecal microbiota from patients with constipation and healthy controls were transplanted into the antibiotic depletion mice model. The mice which received fecal microbiota from patients with constipation presented a reducing in intestinal peristalsis and abnormal defecation parameters including the frequency of pellet expulsion, fecal weight and fecal water content. After fecal microbiota transplantation, the SERT expression in the colonic tissue was significantly upregulated, and the content of 5-HT was decreased which negatively correlated with the gastrointestinal transit time. Moverover, fecal microbiota from the mice which received fecal microbiota from patients with constipation also upregulated SERT in Caco-2 cells. Besides, this process accompanied with the decreased abundance of Clostridium, Lactobacillus, Desulfovibrio, and Methylobacterium and an increased tend of Bacteroides and Akkermansia, which also involved in the impairment of intestinal barrier after FMT. Taken together, intestinal dysbiosis may upregulate the SERT expression and contribute to the development of chronic constipation.

Ameliorative effects of atractylodin on intestinal inflammation and co-occurring dysmotility in both constipation and diarrhea prominent rats

Intestinal disorders often co-occur with inflammation and dysmotility. However, drugs which simultaneously improve intestinal inflammation and co-occurring dysmotility are rarely reported. Atractylodin, a widely used herbal medicine, is used to treat digestive disorders. The present study was designed to characterize the effects of atractylodin on amelioration of both jejunal inflammation and the co-occurring dysmotility in both constipation-prominent (CP) and diarrhea-prominent (DP) rats. The results indicated that atractylodin reduced proinflammatory cytokines TNF-α, IL-1β, and IL-6 in the plasma and inhibited the expression of inflammatory mediators iNOS and NF-kappa B in jejunal segments in both CP and DP rats. The results indicated that atractylodin exerted stimulatory effects and inhibitory effects on the contractility of jejunal segments isolated from CP and DP rats respectively, showing a contractile-state-dependent regulation. Atractylodin-induced contractile-state-dependent regulation was also observed by using rat jejunal segments in low and high contractile states respectively (5 pairs of low/high contractile states). Atractylodin up-regulated the decreased phosphorylation of 20 kDa myosin light chain, protein contents of myosin light chain kinase (MLCK), and MLCK mRNA expression in jejunal segments of CP rats and down-regulated those increased parameters in DP rats. Taken together, atractylodin alleviated rat jejunal inflammation and exerted contractile-state-dependent regulation on the contractility of jejunal segments isolated from CP and DP rats respectively, suggesting the potential clinical implication for ameliorating intestinal inflammation and co-occurring dysmotility.