Dissecting the contribution of host genetics and the microbiome in complex behaviors

The core symptoms of many neurological disorders have traditionally been thought to be caused by genetic variants affecting brain development and function. However, the gut microbiome, another important source of variation, can also influence specific behaviors. Thus, it is critical to unravel the contributions of host genetic variation, the microbiome, and their interactions to complex behaviors. Unexpectedly, we discovered that different maladaptive behaviors are interdependently regulated by the microbiome and host genes in the Cntnap2-/- model for neurodevelopmental disorders. The hyperactivity phenotype of Cntnap2-/- mice is caused by host genetics, whereas the social-behavior phenotype is mediated by the gut microbiome. Interestingly, specific microbial intervention selectively rescued the social deficits in Cntnap2-/- mice through upregulation of metabolites in the tetrahydrobiopterin synthesis pathway. Our findings that behavioral abnormalities could have distinct origins (host genetic versus microbial) may change the way we think about neurological disorders and how to treat them.

Effect of lithium on behavioral disinhibition induced by electrolytic lesion of the median raphe nucleus

RATIONALE

Alterations in brainstem circuits have been proposed as a possible mechanism underlying the etiology of mood disorders. Projections from the median raphe nucleus (MnR) modulate dopaminergic activity in the forebrain and are also part of a behavioral disinhibition/inhibition system that produces phenotypes resembling behavioral variations manifested during manic and depressive phases of bipolar disorder.

OBJECTIVE

The aim of this study is to assess the effect of chronic lithium treatment on behavioral disinhibition induced by MnR lesions.

METHODS

MnR electrolytic lesions were performed in C57BL/6J mice, with sham-operated and intact animals as control groups. Following recovery, mice were chronically treated with lithium (LiCl, added in chow) followed by behavioral testing.

RESULTS

MnR lesion induced manic-like behavioral alterations including hyperactivity in the open field (OF), stereotyped circling, anxiolytic/risk taking in the elevated plus maze (EPM) and light/dark box (LDB) tests, and increased basal body temperature. Lithium was specifically effective in reducing OF hyperactivity and stereotypy but did not reverse (EPM) or had a nonspecific effect (LDB) on anxiety/risk-taking measures. Additionally, lithium decreased saccharin preference and prevented weight loss during single housing.

CONCLUSIONS

Our data support electrolytic lesions of the MnR as an experimental model of a hyper-excitable/disinhibited phenotype consistent with some aspects of mania that are attenuated by the mood stabilizer lithium. Given lithium's relatively specific efficacy in treating mania, these data support the hypothesis that manic symptoms derive not only from the stimulation of excitatory systems but also from inactivation or decreased activity of inhibitory mechanisms.

Cigarette smoke toxins deposited on surfaces: implications for human health

Cigarette smoking remains a significant health threat for smokers and nonsmokers alike. Secondhand smoke (SHS) is intrinsically more toxic than directly inhaled smoke. Recently, a new threat has been discovered - Thirdhand smoke (THS) - the accumulation of SHS on surfaces that ages with time, becoming progressively more toxic. THS is a potential health threat to children, spouses of smokers and workers in environments where smoking is or has been allowed. The goal of this study is to investigate the effects of THS on liver, lung, skin healing, and behavior, using an animal model exposed to THS under conditions that mimic exposure of humans. THS-exposed mice show alterations in multiple organ systems and excrete levels of NNAL (a tobacco-specific carcinogen biomarker) similar to those found in children exposed to SHS (and consequently to THS). In liver, THS leads to increased lipid levels and non-alcoholic fatty liver disease, a precursor to cirrhosis and cancer and a potential contributor to cardiovascular disease. In lung, THS stimulates excess collagen production and high levels of inflammatory cytokines, suggesting propensity for fibrosis with implications for inflammation-induced diseases such as chronic obstructive pulmonary disease and asthma. In wounded skin, healing in THS-exposed mice has many characteristics of the poor healing of surgical incisions observed in human smokers. Lastly, behavioral tests show that THS-exposed mice become hyperactive. The latter data, combined with emerging associated behavioral problems in children exposed to SHS/THS, suggest that, with prolonged exposure, they may be at significant risk for developing more severe neurological disorders. These results provide a basis for studies on the toxic effects of THS in humans and inform potential regulatory policies to prevent involuntary exposure to THS.

An affective disorder in zebrafish with mutation of the glucocorticoid receptor

Upon binding of cortisol, the glucocorticoid receptor (GR) regulates the transcription of specific target genes, including those that encode the stress hormones corticotropin-releasing hormone (CRH) and adrenocorticotropic hormone. Dysregulation of the stress axis is a hallmark of major depression in human patients. However, it is still unclear how glucocorticoid signaling is linked to affective disorders. We identified an adult-viable zebrafish mutant in which the negative feedback on the stress response is disrupted, due to abolition of all transcriptional activity of GR. As a consequence, cortisol is elevated, but unable to signal through GR. When placed into an unfamiliar aquarium ('novel tank'), mutant fish become immobile ('freeze'), show reduced exploratory behavior and do not habituate to this stressor upon repeated exposure. Addition of the antidepressant fluoxetine to the holding water and social interactions restore normal behavior, followed by a delayed correction of cortisol levels. Fluoxetine does not affect the overall transcription of CRH, the mineralocorticoid receptor (MR), the serotonin transporter (Serta) or GR itself. Fluoxetine, however, suppresses the stress-induced upregulation of MR and Serta in both wild-type fish and mutants. Our studies show a conserved, protective function of glucocorticoid signaling in the regulation of emotional behavior and reveal novel molecular aspects of how chronic stress impacts vertebrate brain physiology and behavior. Importantly, the zebrafish model opens up the possibility of high-throughput drug screens in search of new classes of antidepressants.

Delirium: a neurologist's view--the neurology of agitation and overactivity

Delirium is a term used variously to characterize a change in behavior. Neurologists most often use the term to describe a patient who has acutely developed a hyperactive agitated state. In many patients, agitation and overactivity are explained by toxic and metabolic factors and infections. Lesions, especially strokes, in some brain regions have been reported to cause sudden agitation and a hyperactive state, often with an increased amount of speech output, the topics of which flit from one subject to another. Strokes and other lesions that involve the temporal lobes, fusiform and lingual gyri, caudate nucleus, and anterior cingulum have been reported to cause an acute hyperactive state similar to that found in patients with delirium tremens related to alcohol withdrawal.

Learning deficits and agenesis of synapses and myelinated axons in phosphoinositide-3 kinase-deficient mice

Although previous studies have reported a role for phosphoinositide-3 kinase (PI3K) in axonal definition and growth in vitro, it is not clear whether PI3K regulates axonal formation and synaptogenesis in vivo. The goal of the present study was to clarify the role of PI3K in behavioral functions and some underlying neuroanatomical structures. Immunohistochemistry, an electron-microscopic analysis and behavioral tests were carried out. Knockout mice lacking the p85alpha regulatory subunit of PI3K (p85alpha-/- mice) significantly showed learning deficits, restlessness and motivation deficit. Expression of phosphorylated Akt, which indirectly shows the activity of PI3K, was high in myelinated axons, especially in axonal bundles in the striatum of wild-type mice, but was significantly low in the striatum, cerebral cortex and the hippocampal CA3 of p85alpha-/- mice. The axonal marker protein level decreased mainly in the striatum and cerebral cortex of p85alpha-/- mice. In these two regions, myelinated axons are rich in the wild-type mice. However, the density of myelinated axons and myelin thickness were significantly low in the striatum and cerebral cortex of p85alpha-/- mice. Synaptic protein level was clearly decreased in the striatum, cerebral cortex, and hippocampus of p85alpha-/- mice when compared with wild mice. The present results suggest that PI3K plays a role in the generation and/or maintenance of synapses and myelinated axons in the brain and that deficiencies in PI3K activity result in abnormalities in several neuronal functions, including learning, restlessness and motivation.

A combination of valerian and lemon balm is effective in the treatment of restlessness and dyssomnia in children

Efficacy and tolerability of a combined valerian/lemon balm preparation were investigated in an open, multicentre study in children less than 12 years suffering from restlessness and nervous dyskoimesis. Patients were dosed individually by the investigators. In total, 918 children were evaluated for therapeutic efficacy and tolerability. A distinct and convincing reduction in severity was found for all symptoms in the investigators' and parents' ratings. The core symptoms dyssomnia and restlessness were reduced from "moderate/severe" to "mild" or "absent" in most of the patients. In total, 80.9% of the patients who suffered from dyssomnia experienced an improvement for this symptom and 70.4% of the patients with restlessness improved clearly. For the other listed symptoms the total improvement was 37.8% on average. Both, parents and investigators assessed efficacy as to be "very good" or "good" (60.5% and 67.7%, respectively). The tolerability of Euvegal forte was considered as "good" (in 96.7% of the patients it was judged to be "very good" or "good"). No study medication-related adverse events occurred. In conclusion, Euvegal forte was effective in the treatment of younger children with restlessness and dyssomnia and it was very well tolerated.

Clinical features of argyrophilic grain disease: a retrospective survey of cases with neuropsychiatric symptoms

OBJECTIVE

Although argyrophilic grain disease (AGD) appears common in post-mortem series, its clinical features are not widely known. The aim of this study was to explore such clinical features in neuropathologically-confirmed AGD cases.

METHODS

After completing a neuropathological assessment of 386 patients, 33 cases (8.5%) were diagnosed as having AGD; 10 were diagnosed as "pure" cases. These subjects had been admitted to geriatric wards of mental hospitals because of behavioral or neuropsychiatric symptoms requiring medical management. Assessment of the clinical features of the pure cases was based on the evaluations in medical records.

RESULTS

The average age at onset was 82.2 years. Amnesia was the most common initial symptom; irritability and agitation were also common as initial symptoms. During the course of the illness, irritability was the most frequently observed, followed by delusions (mostly delusions of persecution), dysphoria, and then agitation, and apathy. In contrast to the severity of amnesia, other cognitive functions were relatively spared, and the sensorimotor symptoms were not remarkable.

CONCLUSIONS

AGD is a late-onset dementing disorder clinically characterized by amnesia, with other cognitive functions relatively spared, and prominent neuropsychiatric features. These features may correlate with the high level of AGD seen in limbic structures. Future studies are needed to elucidate whether these features are common to all AGD patients or to a clinical subtype with neuropsychiatric symptoms.

Treatment of anxiety, tension and restlessness states with Kava special extract WS 1490 in general practice: a randomized placebo-controlled double-blind multicenter trial

The efficacy and tolerability of 150 mg/d Kava special extract WS 1490 were investigated in a randomized, placebo-controlled, double-blind multicenter study in patients suffering from neurotic anxiety (DSM-III-R diagnoses 300.02, 300.22, 300.23, 300.29, or 309.24). 141 adult, male and female out-patients received 3 x 1 capsule of 50 mg/d WS 1490 or placebo for four weeks, followed by two weeks of observation without study-specific treatment. During randomized treatment the total score of the Anxiety Status Inventory (ASI) observer rating scale showed more pronounced decreases in the WS 1490 group than in the placebo group. Although a treatment group comparison of the post-treatment ASI scores was not significant (p > 0.05), an exploratory analysis of variance across the differences between treatment end and baseline, with center as a second factor, showed superiority of the herbal extract over placebo (p < 0.01, two-sided). 73% of the patients treated with WS 1490 exhibited ASI score decreases > 5 points versus baseline, compared to 56% for placebo. Significant advantages for WS 1490 were also evident in a structured well-being self-rating scale (Bf-S) and the Clinical Global Impressions (CGI), while the Erlangen Anxiety, Tension and Aggression Scale (EAAS) and the Brief Test of Personality Structure (KEPS) showed only minor treatment group differences. Although the results show consistent advantages for WS 1490 over placebo in several psychiatric scales and indicate significant improvements in the patients' general well-being, the differences versus placebo were not as large as in previous trials which employed 300 mg/d of the same extract. WS 1490 was well tolerated, with no influence on liver function tests and only one trivial adverse event (tiredness) attributable to the study drug.

Hemiballism-hemichorea and non-ketotic hyperglycaemia

Three patients with hemiballism-hemichorea caused by non-ketotic hyperglycaemia are presented, two of whom had hyperosmolar non-ketotic hyperglycaemic syndrome. In two of the three patients, the hyperkinesia was the initial presenting symptom of their diabetes mellitus. The hypersensitivity of the postmenopausal dopamine receptor, decreased gamma-aminobutyric acid in the brain in non-ketotic hyperglycaemia, coexisting lacunar infarct in the basal ganglion, and pre-existing metabolic dysfunction in the basal ganglion may all have played a part in the pathogenesis of this movement disorder.

Hemiballism-hemichorea induced by subcortical ischemia

Four patients presented with hemiballism-hemichorea as a clinical manifestation of white matter ischemia. These patients illustrate "positive" motor phenomena rather than limb weakness as a consequence of cerebral ischemia. In each patient, the involuntary movements disappeared following worsening of paresis. Subcortical white matter infarction in three patients and hemodynamic hypo-perfusion in the cerebral hemisphere contralateral to dyskinetic movements were possible causes. Neuroradiologically, none had pathological changes in the vicinity of the subthalamic nucleus. We presume from these observations that ischemia of the subcortical white matter, without involvement of the basal ganglia or the subthalamic nucleus, may cause hemiballism-hemichorea.

[Behavioral and neuropathological analyses of rats with intrahippocampal lesions]

Rats with intrahippocampal lesions produced by infusion of colchicine showed an impairment of learning ability and a decrease in local choline acetyl-transferase activity. In addition, these rats showed bizarre excitable behavior from 3 days after infusion for about an average of 10 days. This included daytime arousal, and easy jumping and squeak reactions against external stimuli as compared to the sham-operated control rats. Moreover, three-dimensional behavioral analysis disclosed: (i) the lesioned rats showed an increase ambulation compared to the control rats, (ii) a more centrally oriented sequence of wandering, while the control rats tended to display peripheral movement around the wall of the test cage, and (iii) they showed a decrease movement associated with rearing compared to the control rats. Neuropathologically, pyramidal neurons and fascia dentata of the lesioned hippocampus showed degeneration from 3 days with a marked astrocytic reaction. In addition, transient over expression of synaptophysin-immunoreactive material was seen in early stage of degeneration and this corresponded ultrastructurally to the presence of swollen synaptic boutons containing numerous non-core synaptic vesicles. These findings appeared to represent in part an abnormal excitement seen in patients with organic brain lesions, in which the excitement has been considered to correspond with neuronal death. Thus, the hippocampus-lesioned rats may provide an animal model to analyse the abnormal behaviors associated with neuronal death.