Saccharomyces boulardii improves the behaviour and emotions of spastic cerebral palsy rats through the gut-brain axis pathway

BACKGROUND

Cerebral palsy (CP) is a kind of disability that influences motion, and children with CP also exhibit depression-like behaviour. Inflammation has been recognized as a contributor to CP and depression, and some studies suggest that the gut-brain axis may be a contributing factor. Our team observed that Saccharomyces boulardii (S. boulardii) could reduce the inflammatory level of rats with hyperbilirubinemia and improve abnormal behaviour. Both CP and depression are related to inflammation, and probiotics can improve depression by reducing inflammation. Therefore, we hypothesize that S. boulardii may improve the behaviour and emotions of spastic CP rats through the gut-brain axis pathway.

METHODS

Our new rat model was produced by resecting the cortex and subcortical white matter. Seventeen-day-old CP rats were exposed to S. boulardii or vehicle control by gastric gavage for 9 days, and different behavioural domains and general conditions were tested. Inflammation was assessed by measuring the inflammatory markers IL-6 and TNF-α. Hypothalamic-pituitary-adrenal (HPA) axis activity was assessed by measuring adrenocorticotropic hormone and corticosterone in the serum. Changes in the gut microbiome were detected by 16S rRNA.

RESULTS

The hemiplegic spastic CP rats we made with typical spastic paralysis exhibited depression-like behaviour. S. boulardii treatment of hemiplegic spastic CP rats improves behaviour and general conditions and significantly reduces the level of inflammation, decreases HPA axis activity, and increases gut microbiota diversity.

CONCLUSIONS

The model developed in this study mimics a hemiplegic spastic cerebral palsy. Damage to the cortex and subcortical white matter of 17-day-old Sprague-Dawley (SD) rats led to spastic CP-like behaviour, and the rats exhibited symptoms of depression-like behaviour. Our results indicate that S. boulardii might have potential in treating hemiplegic spastic CP rat models or as an add-on therapy via the gut-brain axis pathway.

Exploring the Role and Potential of Probiotics in the Field of Mental Health: Major Depressive Disorder

The field of probiotic has been exponentially expanding over the recent decades with a more therapeutic-centered research. Probiotics mediated microbiota modulation within the microbiota–gut–brain axis (MGBA) have been proven to be beneficial in various health domains through pre-clinical and clinical studies. In the context of mental health, although probiotic research is still in its infancy stage, the promising role and potential of probiotics in various mental disorders demonstrated via in-vivo and in-vitro studies have laid a strong foundation for translating preclinical models to humans. The exploration of the therapeutic role and potential of probiotics in major depressive disorder (MDD) is an extremely noteworthy field of research. The possible etio-pathological mechanisms of depression involving inflammation, neurotransmitters, the hypothalamic–pituitary–adrenal (HPA) axis and epigenetic mechanisms potentially benefit from probiotic intervention. Probiotics, both as an adjunct to antidepressants or a stand-alone intervention, have a beneficial role and potential in mitigating anti-depressive effects, and confers some advantages compared to conventional treatments of depression using anti-depressants.

Psychobiotics: Mechanisms of Action, Evaluation Methods and Effectiveness in Applications with Food Products

The gut-brain-microbiota axis consists of a bilateral communication system that enables gut microbes to interact with the brain, and the latter with the gut. Gut bacteria influence behavior, and both depression and anxiety symptoms are directly associated with alterations in the microbiota. Psychobiotics are defined as probiotics that confer mental health benefits to the host when ingested in a particular quantity through interaction with commensal gut bacteria. The action mechanisms by which bacteria exert their psychobiotic potential has not been completely elucidated. However, it has been found that these bacteria provide their benefits mostly through the hypothalamic-pituitary-adrenal (HPA) axis, the immune response and inflammation, and through the production of neurohormones and neurotransmitters. This review aims to explore the different approaches to evaluate the psychobiotic potential of several bacterial strains and fermented products. The reviewed literature suggests that the consumption of psychobiotics could be considered as a viable option to both look after and restore mental health, without undesired secondary effects, and presenting a lower risk of allergies and less dependence compared to psychotropic drugs.

Gut Microbiota and the Neuroendocrine System

The microbial ecosystem that inhabits the gastrointestinal tract of all mammals-the gut microbiota-has been in a symbiotic relationship with its hosts over many millennia. Thanks to modern technology, the myriad of functions that are controlled or modulated by the gut microbiota are beginning to unfold. One of the systems that is emerging to closely interact with the gut microbiota is the body's major neuroendocrine system that controls various body processes in response to stress, the hypothalamic-pituitary-adrenal (HPA) axis. This interaction is of pivotal importance; as various disorders of the microbiota-gut-brain axis are associated with dysregulation of the HPA axis. The present contribution describes the bidirectional communication between the gut microbiota and the HPA axis and delineates the potential underlying mechanisms. In this regard, it is important to note that the communication between the gut microbiota and the HPA axis is closely interrelated with other systems, such as the immune system, the intestinal barrier and blood-brain barrier, microbial metabolites, and gut hormones, as well as the sensory and autonomic nervous systems. These communication pathways will be exemplified through preclinical models of early life stress, beneficial roles of probiotics and prebiotics, evidence from germ-free mice, and antibiotic-induced modulation of the gut microbiota.

Microbiota Signaling Pathways that Influence Neurologic Disease

Though seemingly distinct and autonomous, emerging evidence suggests there is a bidirectional interaction between the intestinal microbiota and the brain. This crosstalk may play a substantial role in neurologic diseases, including anxiety, depression, autism, multiple sclerosis, Parkinson's disease, and, potentially, Alzheimer's disease. Long hypothesized by Metchnikoff and others well over 100 years ago, investigations into the mind-microbe axis is now seeing a rapid resurgence of research. If specific pathways and mechanisms of interaction are understood, it could have broad therapeutic potential, as the microbiome is environmentally acquired and can be modified to promote health. This review will discuss immune, endocrine, and neural system pathways that interconnect the gut microbiota to central nervous system and discuss how these findings might be applied to neurologic disease.

Factors in Early-Life Programming of Reproductive Fitness

Fertility rates have been declining worldwide, with a growing number of young women suffering from infertility. Infectious and inflammatory diseases are important causes of infertility, and recent evidence points to the critical role of the early-life microbial environment in developmental programming of adult reproductive fitness. Our laboratory and others have demonstrated that acute exposure to an immunological challenge early in life has a profound and prolonged impact on male and female reproductive development. This review presents evidence that perinatal exposure to immunological challenge by a bacterial endotoxin, lipopolysaccharide, acts at all levels of the hypothalamic-pituitary-gonadal axis, resulting in long-lasting changes in reproductive function, suggesting that disposition to infertility may begin early in life.

Prospective investigation of the hypothalamo-pituitary-adrenal axis in patients with tularemia

BACKGROUND/AIM

To investigate prospectively the hypothalamo-pituitary-adrenal (HPA) axis by adrenocorticotropic hormone (ACTH) stimulation test.

MATERIALS AND METHODS

Tularemia was diagnosed according to guidelines. An ACTH stimulation test (1 µg) and a dexamethasone suppression test (DST; 1 mg) were performed in patients in the acute phase of tularemia before antibiotic treatment and in the chronic phase.

RESULTS

Nineteen patients (mean age: 41.0 ± 13.2 years; 57.9% female) with tularemia were enrolled in the study in 2011 and 2012. Cortisol response to ACTH stimulation test was sufficient in all patients during the acute phase. After the DST, the cortisol was not suppressed during the acute phase in only one patient. The median control time of 11 patients after acute tularemia was 13 months. During the chronic phase, cortisol response to ACTH stimulation was normal in all patients, and after DST cortisol was suppressed in all patients. The peak cortisol level after the ACTH stimulation test in the acute phase was higher than that in the chronic phase, but the difference was not statistically significant.

CONCLUSION

The HPA axis of patients with tularemia was not significantly affected in the acute and chronic phases.

Relationship between the induction of inflammatory processes and infectious diseases in patients with ischemic stroke

Pro-inflammatory cytokines participate in the induction of ischemic stroke. So far, their participation in the cerebral ischemia was proven for the tumor necrosis factor TNF-α, interleukin-1 (IL-1), and interleukin-6 (IL-6). The release of the pro-inflammatory cytokines into the extracellular space causes the enlargement of the brain damage region, and consequently increases the neurological deficit and negatively affects the survival rate prognoses. That is confirmed by the increased concentration of pro-inflammatory cytokines in blood and the cerebrospinal fluid of patients with brain stroke, as well as by the research on the induced/experimental cerebral ischemia in animals. The pro-inflammatory cytokines participate in the migration of the reactive T lymphocytes to the regions of brain ischemia where they enhance the nerve tissue damage by down-regulation of microcirculation, induce the pro-thrombotic processes and release other neurotoxic cytokines. Also, in the early stage of cerebral ischemia, cytokines activate the axis hypothalamus-pituitary gland-adrenal cortex and increase the cortisol concentration in blood, what results in the decreased resistance to infectious diseases. Administration of the inhibitor of the interleukin-1 receptor (IL-1Ra) inhibits the inflammatory processes in the region of brain ischemia, and subsequently improves the prognosis for the size of the neurological deficit and the survival rate, as well as resistance to infectious diseases.

[Endocytosymbiosis of microorganisms in mammal eukaryotic cells and factors of its regulation]

Morphofunctional equivalents of the process of long-term intracellular prokaryotes--eukaryotes interaction were studied by light and electron microscopy. The mechanisms for adaptation, elaborated in the course of evolution of bacteria-host interaction, were analysed on the ultrastructural level. A concept on the role of hypothalamic nonapeptides, as factors of regulation of intracellular persistence and symbiosis of prokaryotes, is discussed.

Hypothalamus–pituitary–adrenal axis during Trypanosoma cruzi acute infection in mice

Functional interactions between neuroendocrine and immune systems are mediated by similar ligands and receptors, which establish a bi-directional communication that is relevant for homeostasis. We investigated herein the hypothalamus-pituitary-adrenal (HPA) axis in mice acutely infected by Trypanosoma cruzi, the causative agent of Chagas' disease. Parasites were seen in the adrenal gland, whereas T. cruzi specific PCR gene amplification product was found in both adrenal and pituitary glands of infected mice. Histological and immunohistochemical analyses of pituitary and adrenal glands of infected animals revealed several alterations including vascular stasis, upregulation of the extracellular matrix proteins fibronectin and laminin, as well as T cell and macrophage infiltration. Functionally, we detected a decrease in CRH and an increase in corticosterone contents, in hypothalamus and serum respectively. In contrast, we did not find significant changes in the amounts of ACTH in sera of infected animals, whereas the serum levels of the glucocorticoid-stimulating cytokine, IL-6 (interleukin-6), were increased as compared to controls. When we analyzed the effects of T. cruzi in ACTH-producing AtT-20 cell line, infected cultures presented lower levels of ACTH and pro-opiomelanocortin production when compared to controls. In these cells we observed a strong phosphorylation of STAT-3, together with an increased synthesis of IL-6, suppressor of cytokine signaling 3 (SOCS-3) and inhibitor of activated STAT-3 (PIAS-3), which could explain the partial blockage of ACTH production. In conclusion, our data reveal that the HPA axis is altered during acute T. cruzi infection, suggesting direct and indirect influences of the parasite in the endocrine homeostasis.

Use of the cow as a large animal model of uterine infection and immunity

For most of the reproductive cycle in both humans and animals, the uterus is clear of pathogenic bacteria. However, it is readily contaminated with pathogens, such as Escherichia and Tritichomonas species, during sexual intercourse and after parturition. Uterine infection is particularly common after parturition in cattle (Bos taurus), causing clinical disease and infertility. The endocrine and immune responses to uterine infection in cattle have been investigated in vivo and using tissue culture. Cattle are of sufficient size to permit monitoring of reproductive and immune function throughout uterine infections, and primary cell cultures are readily established. In the whole animal, uterine infections suppress GnRH and LH secretion, and inhibit the growth of ovarian follicles and their estradiol secretion. The immune response is characterized by an influx of neutrophils into the uterus and increased concentrations of acute phase proteins in peripheral plasma. In vitro, the endometrial and ovarian cell function is modified by challenge with bacteria, their products such as lipopolysaccharide or pro-inflammatory cytokines. However, it is interesting to note that the susceptibility to uterine infection and the immune response are partially regulated by the ovarian steroid hormone mileu. In conclusion, the ease of working with cattle, the availability of tissues and the similarity of uterine infection between mammals, make Bos taurus a good model for studying uterine infection and immunity.

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.

Suppression of host resistance to Listeria monocytogenes by acute cold/restraint stress: lack of direct IL-6 involvement

We conducted kinetic studies to evaluate the effects of acute cold/restraint stress (ACRS) on both primary and secondary host resistance to Listeria monocytogenes (LM). The involvement of IL-6 also was investigated using IL-6 knockout (KO) mice on the BALB/c background. ACRS dramatically increased the serum corticosterone levels, indicating that ACRS activated the hypothalamic-pituitary-adrenal (HPA) axis. ACRS significantly inhibited host resistance to LM during a primary but not a secondary LM infection. During the primary infection, ACRS caused a significant delay in clearance of LM, loss of body weight, reduced food/water intake, and elevated levels of pro-inflammatory cytokines (IL-6, IL-1beta, and TNFalpha) and IFNgamma. ACRS IL-6 KO mice showed higher LM burdens than did IL-6 KO controls, suggesting that IL-6 is not required for the ACRS-impairment of host resistance. Elevated levels of IL-1beta and TNFalpha may compensate for the absence of IL-6 and maintain the ACRS-induced impairment, in that the serum and splenic IL-1beta and TNFalpha levels were significantly higher in infected ACRS IL-6 KO mice, but not in control IL-6 KO mice, as compared to respective wild type controls. ACRS appears to inhibit IL-6 independent mechanisms associated with innate immunity and/or the development of adaptive immunity, but these reactions are unable to modulate the more efficient secondary immune responses.

Gamma(2)-melanocyte-stimulating hormone suppression of systemic inflammatory responses to endotoxin is associated with modulation of central autonomic and neuroendocrine activities

Central autonomic and neuroendocrine activities are important components of the host response to bacterial inflammation. We demonstrate that intravenous infusion of gamma(2)-melanocyte-stimulating hormone (gamma(2)-MSH), a potent autonomic regulating peptide, prevents lipopolysaccharide (LPS)-induced hypotension and tachycardia, and modulates the ACTH response to endotoxin. In the hypothalamic paraventricular nucleus, a major neuroendocrine and autonomic center, gamma(2)-MSH inhibits LPS-induced increases in CRF mRNA levels, but does not suppress LPS-augmented arginine vasopressin heteronuclear RNA expression. In the locus coeruleus, a brainstem noradrenergic center, gamma(2)-MSH inhibits LPS-induced increases in tyrosine hydroxylase mRNA levels. Gamma(2)-MSH inhibits LPS-induced IL-1beta gene expression in the brain, pituitary and thymus, and prevents increases in plasma NO levels. These findings reveal that gamma(2)-MSH attenuates systemic inflammatory responses to endotoxin and suggest that modulation of central autonomic and neuroendocrine activities by gamma(2)-MSH contributes to its anti-inflammatory effects.

Differential immune responses in mice with left- and right-turning preference

Humoral and cell-mediated immune responses of inbred BALB/c male mice were assayed for differential reactivities associated with behavioral sidedness, which was evaluated by spontaneous rotational behavior in a circular cage model system. Mice with left-turning preference had lower in vivo primary IgM and IgG anti-Keyhole Limpet Hemocyanin (KLH) antibody responses, delayed-type hypersensitivity (DTH) responses, and host-resistance against the intracellular bacteria, Listeria monocytogenes, than mice with right-turning preference. The only immune parameter not shown to be associated with turning preference was the secondary humoral immune response to KLH. The weak innate immune response of left-turners for clearance of Listeria showed close intercorrelation with elevated serum IL-6 levels. Serum corticosterone and splenic norepinephrine levels were differentially increased and decreased by infection, respectively. We suggest that the observed differential immune reactivities of individual animals with same age, gender, and genetic background are associated with functional asymmetries within the brain, that the hypothalamic-pituitary-adrenal (HPA) axis and sympathetic innervation are involved in the regulatory brain: immune interconnection after infection, and that the HPA axis and sympathetic nervous system are involved in the brain laterality effects on immune responses.

Failure to thrive, wasting syndrome, and immunodeficiency in rabies: a hypophyseal/hypothalamic/thymic axis effect of rabies virus

Studies of rabies virus in several animal models consistently showed hypothalamic infection, hypophyseal infection, dramatic growth impairment (in the form of failure to thrive), wasting syndrome, and immune depletion. Rabies virus infection was studied through routine monoclonal antinucleocapsid antibody immunofluorescence and through a peroxidase-antiperoxidase immunoperoxidase method. The latter was modified to detect the in situ production of growth hormone by uninfected and rabies virus-infected adeno-a-pituicytes (with confirmation of the results both in vivo and in vitro). Infection with rabies virus made the specialized pituicytes produce less growth hormone. Growth before rabies virus infection and its reduction due to infection were investigated in a linear regression model. The fit was statistically significant (P less than .05) in all species studied: mouse, rat, rabbit, cow, and cat. Immune depression was studied in terms of alterations in the immunotopography of the thymus and also the specific T- and B-cell homing areas of the spleen (although spleen data are not presented here). On the basis of these results and a thorough review of wasting syndromes encountered in other diseases, a primary failure to thrive and an ensuing wasting syndrome were described and characterized for rabies, and their origin was assigned to a dysfunction of the hypophyseal/hypothalamic/thymic axis associated with at least (but not necessarily only) one of the centrally controlled growth hormones.