MicroRNA-19b associates with Ago2 in the amygdala following chronic stress and regulates the adrenergic receptor beta 1.

Activation of the stress response in the presence of diverse challenges requires numerous adaptive molecular and cellular changes. To identify specific microRNA molecules that are altered following chronic stress, mice were subjected to the chronic social defeat procedure. The amygdala from these mice was collected and a screen for microRNAs that were recruited to the RNA-induced silencing complex and differentially expressed between the stressed and unstressed mice was conducted. One of the microRNAs that were significantly altered was microRNA-19b (miR-19b). Bioinformatics analysis revealed the adrenergic receptor ß-1 (Adrb1) as a potential target for this microRNA with multiple conserved seed sites. Consistent with its putative regulation by miR-19b, Adrb1 levels were reduced in the basolateral amygdala (BLA) following chronic stress. In vitro studies using luciferase assays showed a direct effect of miR-19b on Adrb1 levels, which were not evident when miR-19b seed sequences at the Adrb1 transcript were mutated. To assess the role of miR-19b in memory stabilization, previously attributed to BLA-Adrb1, we constructed lentiviruses designed to overexpress or knockdown miR-19b. Interestingly, adult mice injected bilaterally with miR-19b into the BLA showed lower freezing time relative to control in the cue fear conditioning test, and deregulation of noradrenergic circuits, consistent with downregulation of Adrb1 levels. Knockdown of endogenous BLA-miR-19b levels resulted in opposite behavioral and noradrenergic profile with higher freezing time and increase 3-methoxy-4-hydroxyphenylglycol/noradrenaline ratio. These findings suggest a key role for miR-19b in modulating behavioral responses to chronic stress and Adrb1 as an important target of miR-19b in stress-linked brain regions.

miRNA malfunction causes spinal motor neuron disease.

Defective RNA metabolism is an emerging mechanism involved in ALS pathogenesis and possibly in other neurodegenerative disorders. Here, we show that microRNA (miRNA) activity is essential for long-term survival of postmitotic spinal motor neurons (SMNs) in vivo. Thus, mice that do not process miRNA in SMNs exhibit hallmarks of spinal muscular atrophy (SMA), including sclerosis of the spinal cord ventral horns, aberrant end plate architecture, and myofiber atrophy with signs of denervation. Furthermore, a neurofilament heavy subunit previously implicated in motor neuron degeneration is specifically up-regulated in miRNA-deficient SMNs. We demonstrate that the heavy neurofilament subunit is a target of miR-9, a miRNA that is specifically down-regulated in a genetic model of SMA. These data provide evidence for miRNA function in SMN diseases and emphasize the potential role of miR-9-based regulatory mechanisms in adult neurons and neurodegenerative states.

Novel At-Home Mother's Milk Conductivity Sensing Technology as an Identification System of Delay in Milk Secretory Activation Progress and Early Breastfeeding Problems: Feasibility Assessment.

BACKGROUND: Prolonged exclusive breastfeeding is a public health priority and a personal desire by mothers; however, rates are low with milk supply challenges as a predominant cause. Early breastfeeding management at home is key. Milk electrolytes, mainly sodium ions, are accepted as biomarkers of secretory activation processes throughout the first weeks after birth and predictors for prolonged breastfeeding success, although they are not incorporated into routine care practice. OBJECTIVE: The aim of this study was to test the feasibility of a novel handheld smartphone-operated milk conductivity sensing system that was designed to compute a novel parameter, milk maturation percent (MM%), calculated from milk sample conductivity for tracking individual secretory activation progress in a real-world home setting. METHODS: System performance was initially evaluated in data collected from laboratory-based milk analysis, followed by a retrospective analysis of observational real-world data gathered with the system, on the spot in an at-home setting, implemented by lactation support providers or directly by mothers (N=592). Data collected included milk sample sensing data, baby age, and self-reported breastfeeding status and breastfeeding-related conditions. The data were retroactively classified in a day after birth-dependent manner. Results were compared between groups classified according to breastfeeding exclusivity and breastfeeding problems associated with ineffective breastfeeding and low milk supply. RESULTS: Laboratory analysis in a set of breast milk samples demonstrated a strong correlation between the system's results and sodium ion levels. In the real-world data set, a total of 1511 milk sensing records were obtained on the spot with over 592 real-world mothers. Data gathered with the system revealed a typical time-dependent increase in the milk maturation parameter (MM%), characterized by an initial steep increase, followed by a moderate increase, and reaching a plateau during the first weeks postpartum. Additionally, MM% levels captured by the system were found to be sensitive to breastfeeding status classifications of exclusive breastfeeding and breastfeeding problems, manifested by differences in group means in the several-day range after birth, predominantly during the first weeks postpartum. Differences could also be demonstrated for the per-case time after birth-dependent progress in individual mothers. CONCLUSIONS: This feasibility study demonstrates that the use of smart milk conductivity sensing technology can provide a robust, objective measure of individual breastfeeding efficiency, facilitating remote data collection within a home setting. This system holds considerable potential to augment both self-monitoring and remote breastfeeding management capabilities, as well as to refine clinical classifications. To further validate the clinical relevance and potential of this home milk monitoring tool, future controlled clinical studies are necessary, which will provide insights into its impact on user and care provider satisfaction and its potential to meet breastfeeding success goals.

Resilience to chronic stress is mediated by hippocampal brain-derived neurotrophic factor.

Chronic stress is a trigger for several psychiatric disorders, including depression; however, critical individual differences in resilience to both the behavioral and the neurochemical effects of stress have been reported. A prominent mechanism by which the brain reacts to acute and chronic stress is activation of the hypothalamic-pituitary-adrenal (HPA) axis, which is inhibited by the hippocampus via a polysynaptic circuit. Alterations in secretion of stress hormones and levels of brain-derived neurotrophic factor (BDNF) in the hippocampus were implicated in depression and the effects of antidepressant medications. However, the potential role of hippocampal BDNF in behavioral resilience to chronic stress and in the regulation of the HPA axis has not been evaluated. In the present study, Sprague Dawley rats were subjected to 4 weeks of chronic mild stress (CMS) to induce depressive-like behaviors after lentiviral vectors were used to induce localized BDNF overexpression or knockdown in the hippocampus. The behavioral outcome was measured during 3 weeks after the CMS procedure, then plasma samples were taken for measurements of corticosterone levels, and finally hippocampal tissue was taken for BDNF measurements. We found that hippocampal BDNF expression plays a critical role in resilience to chronic stress and that reduction of hippocampal BDNF expression in young, but not adult, rats induces prolonged elevations in corticosterone secretion. The present study describes a mechanism for individual differences in responses to chronic stress and implicates hippocampal BDNF in the development of neural circuits that control adequate stress adaptations.

MicroRNA as repressors of stress-induced anxiety: the case of amygdalar miR-34.

The etiology and pathophysiology of anxiety and mood disorders is linked to inappropriate regulation of the central stress response. To determine whether microRNAs have a functional role in the regulation of the stress response, we inactivated microRNA processing by a lentiviral-induced local ablation of the Dicer gene in the central amygdala (CeA) of adult mice. CeA Dicer ablation induced a robust increase in anxiety-like behavior, whereas manipulated neurons survive and appear to exhibit normal gross morphology in the time period examined. We also observed that acute stress in wild-type mice induced a differential expression profile of microRNAs in the amygdala. Bioinformatic analysis identified putative gene targets for these stress-responsive microRNAs, some of which are known to be associated with stress. One of the prominent stress-induced microRNAs found in this screen, miR-34c, was further confirmed to be upregulated after acute and chronic stressful challenge and downregulated in Dicer ablated cells. Lentivirally mediated overexpression of miR34c specifically within the adult CeA induced anxiolytic behavior after challenge. Of particular interest, one of the miR-34c targets is the stress-related corticotropin releasing factor receptor type 1 (CRFR1) mRNA, regulated via a single evolutionary conserved seed complementary site on its 3' UTR. Additional in vitro studies demonstrated that miR-34c reduces the responsiveness of cells to CRF in neuronal cells endogenously expressing CRFR1. Our results suggest a physiological role for microRNAs in regulating the central stress response and position them as potential targets for treatment of stress-related disorders.

The posterior parietal cortex in recognition memory: a neuropsychological study.

Several recent functional neuroimaging studies have reported robust bilateral activation (L>R) in lateral posterior parietal cortex and precuneus during recognition memory retrieval tasks. It has not yet been determined what cognitive processes are represented by those activations. In order to examine whether parietal lobe-based processes are necessary for basic episodic recognition abilities, we tested a group of 17 first-incident CVA patients whose cortical damage included (but was not limited to) extensive unilateral posterior parietal lesions. These patients performed a series of tasks that yielded parietal activations in previous fMRI studies: yes/no recognition judgments on visual words and on colored object pictures and identifiable environmental sounds. We found that patients with left hemisphere lesions were not impaired compared to controls in any of the tasks. Patients with right hemisphere lesions were not significantly impaired in memory for visual words, but were impaired in recognition of object pictures and sounds. Two lesion--behavior analyses--area-based correlations and voxel-based lesion symptom mapping (VLSM)---indicate that these impairments resulted from extra-parietal damage, specifically to frontal and lateral temporal areas. These findings suggest that extensive parietal damage does not impair recognition performance. We suggest that parietal activations recorded during recognition memory tasks might reflect peri-retrieval processes, such as the storage of retrieved memoranda in a working memory buffer for further cognitive processing.

Use of lipophilic near-infrared dye in whole-body optical imaging of hematopoietic cell homing.

We develop an optical whole-body imaging technique for monitoring normal and leukemic hematopoietic cell homing in vivo. A recently developed near-infrared (NIR) lipophilic carbocyanine dye 1,1'-dioctadecyl-3,3,3',3'-tetramethylindotricarbocyanine iodide (DiR) is used to safely and directly label the membranes of human leukemic Pre-B ALL G2 cell lines as well as primary murine lymphocytes and erythrocytes. DiR has absorption and fluorescence maxima at 750 and 782 nm, respectively, which corresponds to low light absorption and autofluorescence in living tissues. This allows us to obtain a significant signal with very low background level. A charge-coupled device (CCD)-based imager is used for noninvasive whole-body imaging of DiR-labeled cell homing in intact animals. This powerful technique can potentially visualize any cell type without use of specific antibodies conjugated with NIR fluorescent tag or loading cells with transporter-delivered NIR fluorophores. Thus, in vivo imaging based on NIR lipophilic carbocyanine dyes in combination with advanced optical techniques may serve as a powerful alternative or complementation to other small animal imaging methods.

Ucn3 and CRF-R2 in the medial amygdala regulate complex social dynamics.

Social encounters are associated with varying degrees of emotional arousal and stress. The mechanisms underlying adequate socioemotional balance are unknown. The medial amygdala (MeA) is a brain region associated with social behavior in mice. Corticotropin-releasing factor receptor type-2 (CRF-R2) and its specific ligand urocortin-3 (Ucn3), known components of the behavioral stress response system, are highly expressed in the MeA. Here we show that mice deficient in CRF-R2 or Ucn3 exhibit abnormally low preference for novel conspecifics. MeA-specific knockdown of Crfr2 (Crhr2) in adulthood recapitulated this phenotype. In contrast, pharmacological activation of MeA CRF-R2 or optogenetic activation of MeA Ucn3 neurons increased preference for novel mice. Furthermore, chemogenetic inhibition of MeA Ucn3 neurons elicited pro-social behavior in freely behaving groups of mice without affecting their hierarchal structure. These findings collectively suggest that the MeA Ucn3-CRF-R2 system modulates the ability of mice to cope with social challenges.

MicroRNA 135 is essential for chronic stress resiliency, antidepressant efficacy, and intact serotonergic activity.

The link between dysregulated serotonergic activity and depression and anxiety disorders is well established, yet the molecular mechanisms underlying these psychopathologies are not fully understood. Here, we explore the role of microRNAs in regulating serotonergic (5HT) neuron activity. To this end, we determined the specific microRNA "fingerprint" of 5HT neurons and identified a strong microRNA-target interaction between microRNA 135 (miR135), and both serotonin transporter and serotonin receptor-1a transcripts. Intriguingly, miR135a levels were upregulated after administration of antidepressants. Genetically modified mouse models, expressing higher or lower levels of miR135, demonstrated major alterations in anxiety- and depression-like behaviors, 5HT levels, and behavioral response to antidepressant treatment. Finally, miR135a levels in blood and brain of depressed human patients were significantly lower. The current results suggest a potential role for miR135 as an endogenous antidepressant and provide a venue for potential treatment and insights into the onset, susceptibility, and heterogeneity of stress-related psychopathologies.

Altered brain-derived neurotrophic factor expression in the ventral tegmental area, but not in the hippocampus, is essential for antidepressant-like effects of electroconvulsive therapy.

BACKGROUND: Impaired neuronal plasticity and, specifically, altered expression of brain-derived neurotrophic factor (BDNF) were shown to play a critical role in depressive behavior and the mechanism of various antidepressant treatments including electroconvulsive therapy (ECT). Interestingly, opposing roles were suggested for BDNF in the hippocampus and the ventral tegmental area (VTA), while interactions between these regions were shown on various levels. Here, we evaluated whether BDNF plays an essential role in the antidepressant-like effects of ECT and performed a direct comparison between BDNF manipulations in the VTA and the hippocampus. METHODS: Knockdown or overexpression of BDNF was induced in hippocampus or VTA of rats by microinjection of specific lentiviral vectors. The effects of these manipulations on antidepressant outcomes of ECT were evaluated by the forced swim test and by sucrose preference measurements, and BDNF expression levels were assessed in other reward-related brain regions. RESULTS: Here, we show that whereas ECT increased hippocampal BDNF expression, induction of hippocampal BDNF knockdown did not block its antidepressant-like effect. Importantly, we found that ECT caused a robust reduction in VTA BDNF levels. Moreover, VTA BDNF knockdown alone was sufficient to induce an antidepressant-like effect, and VTA BDNF overexpression blocked the antidepressant-like effect of ECT. CONCLUSIONS: While neuroplastic alterations, as expressed by changes in BDNF expression within different brain regions, are induced by ECT, the antidepressant-like effect of ECT in an animal model depends on reduction of VTA BDNF expression but not on the elevation of hippocampal BDNF expression.

Enhancement of consolidated long-term memory by overexpression of protein kinase Mzeta in the neocortex.

Memories are more easily disrupted than improved. Many agents can impair memories during encoding and consolidation. In contrast, the armamentarium of potential memory enhancers is so far rather modest. Moreover, the effect of the latter appears to be limited to enhancing new memories during encoding and the initial period of cellular consolidation, which can last from a few minutes to hours after learning. Here, we report that overexpression in the rat neocortex of the protein kinase C isozyme protein kinase Mζ (PKMζ) enhances long-term memory, whereas a dominant negative PKMζ disrupts memory, even long after memory has been formed.