Theanine, Uric acid, Mood, and Sinus healthMarch 2016
By Life Extension
The association between depression and leukocyte telomere length: a meta-analysis.
BACKGROUND: Telomeres protect the ends of chromosomes, and shorter leukocyte telomeres are associated with poor health. Depression may be associated with the shortening of leukocyte telomeres. The present study set out to consolidate the varying effect sizes found so far in studies of depression and telomere length and to identify moderators of the relationship between depression and telomere length. METHODS: A meta-analytic investigation of the relationship between depression and leukocyte telomere length used information from 21,040 participants. RESULTS: A significant effect size, r = -.12, P < .001, indicated that depression was associated with shorter telomere length. Several variables significantly moderated effect size. Concurrent associations (k = 25) between depression and telomere length were significantly stronger than longitudinal associations (k = 5). Studies that used the Southern blot (k = 3) and fluorescent in situ hybridization (FISH; k = 2) assays to measure telomere length showed larger effect sizes than studies that used quantitative polymerase chain reaction (qPCR; k = 25). Finally, study reports that indicated that the telomere assays were conducted blind to depression level of participants (k = 11) had significantly lower effect sizes than those of other studies (k = 19). CONCLUSIONS: The significant relationship between depression and shorter telomere length is consistent with a theoretical model positing that distress, such as experienced in depression, results in physiological changes leading to shortened telomeres.
Depress Anxiety . 2015 Apr;32(4):229-38
Assessment of psychotropic-like properties of a probiotic formulation (Lactobacillus helveticus R0052 and Bifidobacterium longum R0175) in rats and human subjects.
In a previous clinical study, a probiotic formulation (PF) consisting of Lactobacillus helveticus R0052 and Bifidobacterium longum R0175 (PF) decreased stress-induced gastrointestinal discomfort. Emerging evidence of a role for gut microbiota on central nervous system functions therefore suggests that oral intake of probiotics may have beneficial consequences on mood and psychological distress. The aim of the present study was to investigate the anxiolytic-like activity of PF in rats, and its possible effects on anxiety, depression, stress and coping strategies in healthy human volunteers. In the preclinical study, rats were daily administered PF for 2 weeks and subsequently tested in the conditioned defensive burying test, a screening model for anti-anxiety agents. In the clinical trial, volunteers participated in a double-blind, placebo-controlled, randomised parallel group study with PF administered for 30 d and assessed with the Hopkins Symptom Checklist (HSCL-90), the Hospital Anxiety and Depression Scale (HADS), the Perceived Stress Scale, the Coping Checklist (CCL) and 24 h urinary free cortisol (UFC). Daily subchronic administration of PF significantly reduced anxiety-like behaviour in rats (P < 0·05) and alleviated psychological distress in volunteers, as measured particularly by the HSCL-90 scale (global severity index, P < 0·05; somatisation, P < 0·05; depression, P < 0·05; and anger-hostility, P < 0·05), the HADS (HADS global score, P < 0·05; and HADS-anxiety, P < 0·06), and by the CCL (problem solving, P < 0·05) and the UFC level (P < 0·05). L. helveticus R0052 and B. longum R0175 taken in combination display anxiolytic-like activity in rats and beneficial psychological effects in healthy human volunteers.
Br J Nutr. 2011 Mar;105(5):755-64
Mood and gut feelings.
Evidence is accumulating to suggest that gut microbes (microbiota) may be involved in neural development and function, both peripherally in the enteric nervous system and centrally in the brain. There is an increasing and intense current interest in the role that gut bacteria play in maintaining the health of the host. Altogether the mass of intestinal bacteria represents a virtual inner organ with 100 times the total genetic material contained in all the cells in the human body. Surprisingly, the characterization of this extraordinarily diverse population is only just beginning, since some 60% of these microbes have never been cultured. Commensal organisms live in a state of harmonious symbiosis with each other and their host, however, a disordered balance amongst gut microbes is now thought to be an associated or even causal factor for chronic medical conditions as varied as obesity and inflammatory bowel diseases. While evidence is still limited in psychiatric illnesses, there are rapidly coalescing clusters of evidence which point to the possibility that variations in the composition of gut microbes may be associated with changes in the normal functioning of the nervous system. This review focuses on these data and suggests that the concept should be explored further to increase our understanding of mood disorders, and possibly even uncover missing links to a number of co-morbid medical diseases.
Brain Behav Immun. 2010 Jan;24(1):9-16.
Intestinal barrier function and the brain-gut axis.
The luminal-mucosal interface of the intestinal tract is the first relevant location where microorganism-derived antigens and all other potentially immunogenic particles face the scrutiny of the powerful mammalian immune system. Upon regular functioning conditions, the intestinal barrier is able to effectively prevent most environmental and external antigens to interact openly with the numerous and versatile elements that compose the mucosal-associated immune system. This evolutionary super system is capable of processing an astonishing amount of antigens and non-immunogenic particles, approximately 100 tons in one individual lifetime, only considering food-derived components. Most important, to develop oral tolerance and proper active immune responses needed to prevent disease and inflammation, this giant immunogenic load has to be managed in a way that physiological inflammatory balance is constantly preserved. Adequate functioning of the intestinal barrier involves local and distant regulatory networks integrating the so-called brain-gut axis. Along this complex axis both brain and gut structures participate in the processing and execution of response signals to external and internal changes coming from the digestive tract, using multidirectional pathways to communicate. Dysfunction of brain-gut axis facilitates malfunctioning of the intestinal barrier, and vice versa, increasing the risk of uncontrolled immunological reactions that may trigger mucosal and brain low-grade inflammation, a putative first step to the initiation of more permanent gut disorders. In this chapter, we describe the structure, function and interactions of intestinal barrier, microbiota and brain-gut axis in both healthy and pathological conditions.
Adv Exp Med Biol. 2014;817:73-113
Gut-microbiota-brain axis and its effect on neuropsychiatric disorders with suspected immune dysregulation.
PURPOSE: Gut microbiota regulate intestinal function and health. However, mounting evidence indicates that they can also influence the immune and nervous systems and vice versa. This article reviews the bidirectional relationship between the gut microbiota and the brain, termed the microbiota-gut-brain (MGB) axis, and discusses how it contributes to the pathogenesis of certain disorders that may involve brain inflammation. METHODS: Articles were identified with a search of Medline (starting in 1980) by using the key words anxiety, attention-deficit hypersensitivity disorder (ADHD), autism, cytokines, depression, gut, hypothalamic-pituitary-adrenal (HPA) axis, inflammation, immune system, microbiota, nervous system, neurologic, neurotransmitters, neuroimmune conditions, psychiatric, and stress. FINDINGS: Various afferent or efferent pathways are involved in the MGB axis. Antibiotics, environmental and infectious agents, intestinal neurotransmitters/neuromodulators, sensory vagal fibers, cytokines, and essential metabolites all convey information to the central nervous system about the intestinal state. Conversely, the hypothalamic-pituitary-adrenal axis, the central nervous system regulatory areas of satiety, and neuropeptides released from sensory nerve fibers affect the gut microbiota composition directly or through nutrient availability. Such interactions seem to influence the pathogenesis of a number of disorders in which inflammation is implicated, such as mood disorder, autism-spectrum disorders, attention-deficit hypersensitivity disorder, multiple sclerosis, and obesity. IMPLICATIONS: Recognition of the relationship between the MGB axis and the neuroimmune systems provides a novel approach for better understanding and management of these disorders. Appropriate preventive measures early in life or corrective measures such as use of psychobiotics, fecal microbiota transplantation, and flavonoids are discussed.
Clin Ther. 2015 May 1;37(5):984-95
Postnatal microbial colonization programs the hypothalamic-pituitary-adrenal system for stress response in mice.
Indigenous microbiota have several beneficial effects on host physiological functions; however, little is known about whether or not postnatal microbial colonization can affect the development of brain plasticity and a subsequent physiological system response. To test the idea that such microbes may affect the development of neural systems that govern the endocrine response to stress, we investigated hypothalamic-pituitary-adrenal (HPA) reaction to stress by comparing germfree (GF), specific pathogen free (SPF) and gnotobiotic mice. Plasma ACTH and corticosterone elevation in response to restraint stress was substantially higher in GF mice than in SPF mice, but not in response to stimulation with ether. Moreover, GF mice also exhibited reduced brain-derived neurotrophic factor expression levels in the cortex and hippocampus relative to SPF mice. The exaggerated HPA stress response by GF mice was reversed by reconstitution with Bifidobacterium infantis. In contrast, monoassociation with enteropathogenic Escherichia coli, but not with its mutant strain devoid of the translocated intimin receptor gene, enhanced the response to stress. Importantly, the enhanced HPA response of GF mice was partly corrected by reconstitution with SPF faeces at an early stage, but not by any reconstitution exerted at a later stage, which therefore indicates that exposure to microbes at an early developmental stage is required for the HPA system to become fully susceptible to inhibitory neural regulation. These results suggest that commensal microbiota can affect the postnatal development of the HPA stress response in mice.
J Physiol. 2004 Jul 1;558(Pt 1):263-75
Early life stress alters behavior, immunity, and microbiota in rats: implications for irritable bowel syndrome and psychiatric illnesses.
BACKGROUND: Adverse early life events are associated with a maladaptive stress response system and might increase the vulnerability to disease in later life. Several disorders have been associated with early life stress, ranging from depression to irritable bowel syndrome. This makes the identification of the neurobiological substrates that are affected by adverse experiences in early life invaluable. METHODS: The purpose of this study was to assess the effect of early life stress on the brain-gut axis. Male rat pups were stressed by separating them from their mothers for 3 hours daily between postnatal days 2-12. The control group was left undisturbed with their mothers. Behavior, immune response, stress sensitivity, visceral sensation, and fecal microbiota were analyzed. RESULTS: The early life stress increased the number of fecal boli in response to a novel stress. Plasma corticosterone was increased in the maternally separated animals. An increase in the systemic immune response was noted in the stressed animals after an in vitro lipopolysaccharide challenge. Increased visceral sensation was seen in the stressed group. There was an alteration of the fecal microbiota when compared with the control group. CONCLUSIONS: These results show that this form of early life stress results in an altered brain-gut axis and is therefore an important model for investigating potential mechanistic insights into stress-related disorders including depression and IBS.
Biol Psychiatry. 2009 Feb 1;65(3):263-7