Aberrant cortical projections to amygdala GABAergic neurons contribute to developmental circuit dysfunction following early life stress.

Early life stress (ELS) results in enduring dysfunction of the corticolimbic circuitry, underlying emotional and social behavior. However, the neurobiological mechanisms involved remain elusive. Here, we have combined viral tracing and electrophysiological techniques to study the effects of maternal separation (MS) on frontolimbic connectivity and function in young (P14-21) rats. We report that aberrant prefrontal inputs to basolateral amygdala (BLA) GABAergic interneurons transiently increase the strength of feed-forward inhibition in the BLA, which raises LTP induction threshold in MS treated male rats. The enhanced GABAergic activity after MS exposure associates with lower functional synchronization within prefrontal-amygdala networks in vivo. Intriguingly, no differences in these parameters were detected in females, which were also resistant to MS dependent changes in anxiety-like behaviors. Impaired plasticity and synchronization during the sensitive period of circuit refinement may contribute to long-lasting functional changes in the prefrontal-amygdaloid circuitry that predispose to neuropsychiatric conditions later on in life.

Downregulation of kainate receptors regulating GABAergic transmission in amygdala after early life stress is associated with anxiety-like behavior in rodents.

Early life stress (ELS) is a well-characterized risk factor for mood and anxiety disorders. GABAergic microcircuits in the amygdala are critically implicated in anxiety; however, whether their function is altered after ELS is not known. Here we identify a novel mechanism by which kainate receptors (KARs) modulate feedforward inhibition in the lateral amygdala (LA) and show that this mechanism is downregulated after ELS induced by maternal separation (MS). Specifically, we show that in control rats but not after MS, endogenous activity of GluK1 subunit containing KARs disinhibit LA principal neurons during activation of cortical afferents. GluK1 antagonism attenuated excitability of parvalbumin (PV)-expressing interneurons, resulting in loss of PV-dependent inhibitory control and an increase in firing of somatostatin-expressing interneurons. Inactivation of Grik1 expression locally in the adult amygdala reduced ongoing GABAergic transmission and was sufficient to produce a mild anxiety-like behavioral phenotype. Interestingly, MS and GluK1-dependent phenotypes showed similar gender specificity, being detectable in male but not female rodents. Our data identify a novel KAR-dependent mechanism for cell-type and projection-specific functional modulation of the LA GABAergic microcircuit and suggest that the loss of GluK1 KAR function contributes to anxiogenesis after ELS.

Effects of Medicinal Fungi-Derived ß-Glucan on Tumor Progression.

ß-Glucans have been studied in animal species, from earthworms to humans. They form a heterogenous group of glucose polymers found in fungi, plants, bacteria, and seaweed. ß-Glucans have slowly emerged as an important target for the recognition of pathogens. In the current review, we highlight the major roles of mushroom-derived ß-glucans on cancer progression.

Hypolipidemic Effects of ß-Glucans, Mannans, and Fucoidans: Mechanism of Action and Their Prospects for Clinical Application.

The search for lipid-lowering drugs is important for clinical medicine. This review summarizes our research findings regarding the hypolipidemic activity of polysaccharides. There are several validated agents altering lipid levels which reduce the risk of atherosclerotic cardiovascular events. Nonetheless, for many people, the risk of such an event remains unacceptably high despite treatment with these agents. This situation has prompted the search for new therapies to reduce the residual cardiovascular risk. The lipid-lowering effect of ß-glucans consumed with food was demonstrated in patients with atherosclerosis. The mechanism of the protective effect of ß-glucans is poorly studied. The effects of ß-glucans are mediated by Toll-like receptors, by dectin-1, and possibly by other receptors. Nevertheless, the mechanism of the protective action of ß-glucan in lipemic mice has been studied insufficiently. This review will present up-to-date information regarding experimental hypolipidemic polysaccharide compounds that hold promise for medicine. Phagocyte-specific chitotriosidase in humans contributes to innate immune responses against chitin-containing fungi. This enzyme has been first described in patients with Gaucher disease and serves as an important diagnostic biomarker. It has been reported that, in mice, chitin particles of certain size are recognized by macrophages through Toll-like receptors, dectin-1, and to a lesser extent through mannose receptor.

Kainate receptors regulate development of glutamatergic synaptic circuitry in the rodent amygdala.

Perturbed information processing in the amygdala has been implicated in developmentally originating neuropsychiatric disorders. However, little is known on the mechanisms that guide formation and refinement of intrinsic connections between amygdaloid nuclei. We demonstrate that in rodents the glutamatergic connection from basolateral to central amygdala (BLA-CeA) develops rapidly during the first 10 postnatal days, before external inputs underlying amygdala-dependent behaviors emerge. During this restricted period of synaptic development, kainate-type of ionotropic glutamate receptors (KARs) are highly expressed in the BLA and tonically activated to regulate glutamate release via a G-protein-dependent mechanism. Genetic manipulation of this endogenous KAR activity locally in the newborn LA perturbed development of glutamatergic input to CeA, identifying KARs as a physiological mechanism regulating formation of the glutamatergic circuitry in the amygdala.

NETO1 Guides Development of Glutamatergic Connectivity in the Hippocampus by Regulating Axonal Kainate Receptors.

Kainate-type glutamate receptors (KARs) are highly expressed in the developing brain, where they are tonically activated to modulate synaptic transmission, network excitability and synaptogenesis. NETO proteins are auxiliary subunits that regulate biophysical properties of KARs; however, their functions in the immature brain are not known. Here, we show that NETO1 guides the development of the rodent hippocampal CA3-CA1 circuitry via regulating axonal KARs. NETO deficiency reduced axonal targeting of most KAR subunits in hippocampal neurons in a subtype independent manner. As an interesting exception, axonal delivery of GluK1c was strongly and selectively impaired in the Neto1-/-, but not Neto2-/-, neurons. Correspondingly, the presynaptic GluK1 KAR activity that tonically inhibits glutamate release at immature CA3-CA1 synapses was completely lost in the absence of NETO1 but not NETO2. The deficit in axonal KARs at Neto1-/- neurons resulted in impaired synaptogenesis and perturbed synchronization of CA3 and CA1 neuronal populations during development in vitro. Both these Neto1-/- phenotypes were fully rescued by overexpression of GluK1c, emphasizing the role of NETO1/KAR complex in development of efferent connectivity. Together, our data uncover a novel role for NETO1 in regulation of axonal KARs and identify its physiological significance in development of the CA3-CA1 circuit.

The gene expression profile of a drug metabolism system and signal transduction pathways in the liver of mice treated with tert-butylhydroquinone or 3-(3'-tert-butyl-4'-hydroxyphenyl)propylthiosulfonate of sodium.

Tert-butylhydroquinone (tBHQ) is a highly effective phenolic antioxidant used in edible oils and fats in foods as well as in medicines and cosmetics. TBHQ has been shown to have both chemoprotective and carcinogenic effects. Furthermore, it has potential anti-inflammatory, antiatherogenic, and neuroprotective activities. TBHQ induces phase II detoxification enzymes via the Keap1/Nrf2/ARE mechanism, which contributes to its chemopreventive functions. Nonetheless, there is growing evidence that biological effects of tBHQ may be mediated by Nrf2-independent mechanisms related to various signaling cascades. Here, we studied changes in gene expression of phase I, II, and III drug metabolizing enzymes/transporters as well as protein levels and activities of cytochromes P450 (CYPs) elicited by tBHQ and its structural homolog TS-13 in the mouse liver. Next, we carried out gene expression analysis to identify signal transduction pathways modulated by the antioxidants. Mice received 100 mg/kg tBHQ or TS-13 per day or only vehicle. The liver was collected at 12 hours and after 7 days of the treatment. Protein and total RNA were extracted. Gene expression was analyzed using Mouse Drug Metabolism and Signal Transduction PathwayFinder RT2Profiler™PCR Arrays. A western blot analysis was used to measure protein levels and a fluorometric assay was employed to study activities of CYPs. Genes that were affected more than 1.5-fold by tBHQ or TS-13 treatment compared with vehicle were identified. Analysis of the gene expression data revealed changes in various genes that are important for drug metabolism, cellular defense mechanisms, inflammation, apoptosis, and cell cycle regulation. Novel target genes were identified, including xenobiotic metabolism genes encoding CYPs, phase II/III drug metabolizing enzymes/transporters. For Cyp1a2 and Cyp2b, we observed an increase in protein levels and activities during tBHQ or TS-13 treatment. Changes were found in the gene expression regulated by NFκB, androgen, retinoic acid, PI3K/AKT, Wnt, Hedgehog and other pathways.

A comparative study of the hypolipidaemic effects of a new polysaccharide, mannan Candida albicans serotype A, and atorvastatin in mice with poloxamer 407-induced hyperlipidaemia.

OBJECTIVES: We evaluated the hypolipidaemic effect of mannan Candida albicans serotype A, relative to atorvastatin, in a mouse model of hyperlipidaemia. METHODS: Mannan serotype A was investigated in vitro and in vivo to determine its effects on macrophage proliferation, nitric oxide (NO) production by cultured macrophages, serum and liver lipids, changes in liver morphology and serum chitotriosidase activity and its expression in the liver. KEY FINDINGS: Mannan serotype A stimulates the macrophage proliferation and NO production in murine peritoneal macrophages in vitro. The activity of serum chitotriosidase (an enzyme released from the activated macrophages) was found to be significantly increased in P-407-induced hyperlipidaemic mice pretreated with low-dose mannan compared with mice administered P-407 only. Mannan treatment in mice was shown to significantly increase the chitotriosidase expression in the liver of both non-hyperlipidaemic and P-407-induced hyperlipidaemic mice. Lastly, mice pretreated with mannan before the induction of hyperlipidaemia with P-407 showed a significant reduction in the serum concentration of atherogenic LDL cholesterol, total cholesterol, triglycerides and liver triglycerides. CONCLUSIONS: It is suggested that mannan serotype A, like ß-glucan, may represent another hypolipidaemic agent, which could potentially be used as an adjunctive therapy with conventional antihyperlipidaemic drugs (statins and fibrates) in humans.

Axonal Kainate Receptors Modulate the Strength of Efferent Connectivity by Regulating Presynaptic Differentiation.

Kainate type of glutamate receptors (KARs) are highly expressed during early brain development and may influence refinement of the circuitry, via modulating synaptic transmission and plasticity. KARs are also localized to axons, however, their exact roles in regulating presynaptic processes remain controversial. Here, we have used a microfluidic chamber system allowing specific manipulation of KARs in presynaptic neurons to study their functions in synaptic development and function in vitro. Silencing expression of endogenous KARs resulted in lower density of synaptophysin immunopositive puncta in microfluidically isolated axons. Various recombinant KAR subunits and pharmacological compounds were used to dissect the mechanisms behind this effect. The calcium permeable (Q) variants of the low-affinity (GluK1-3) subunits robustly increased synaptophysin puncta in axons in a manner that was dependent on receptor activity and PKA and PKC dependent signaling. Further, an associated increase in the mean active zone length was observed in electron micrographs. Selective presynaptic expression of these subunits resulted in higher success rate of evoked EPSCs consistent with higher probability of glutamate release. In contrast, the calcium-impermeable (R) variant of GluK1 or the high-affinity subunits (GluK4,5) had no effect on synaptic density or transmission efficacy. These data suggest that calcium permeable axonal KARs promote efferent connectivity by increasing the density of functional presynaptic release sites.

Filaggrin mutations in a Western siberian population and their association with atopic dermatitis in children.

We determined the frequencies of null mutations of the FLG gene--2282del4, R501X, R2447X, 3702delG, S3247X, and the 12-repeat allele (rs12730241)--among 460 Caucasians of the city of Novosibirsk, Russia. The frequency was 17.7% for rs12730241, 2.73% for 2282del4, 0.22% for R501X, 0.33% for R2447X, and 0% for 3702delG and S3247X in a western Siberian population. A case-control study showed that the deletion 2282del4 was associated with atopic dermatitis in children (odds ratio 7.01; p<0.001). The other mutations were not.