MicroRNA 101b Is Downregulated in the Prefrontal Cortex of a Genetic Model of Depression and Targets the Glutamate Transporter SLC1A1 (EAAT3) in Vitro.

BACKGROUND: MicroRNAs (miRNAs) are small regulatory molecules that cause translational repression by base pairing with target mRNAs. Cumulative evidence suggests that changes in miRNA expression may in part underlie the pathophysiology and treatment of neuropsychiatric disorders, including major depressive disorder (MDD). METHODS: A miRNA expression assay that can simultaneously detect 423 rat miRNAs (miRBase v.17) was used to profile the prefrontal cortex (PFC) of a genetic rat model of MDD (the Flinders Sensitive Line [FSL]) and the controls, the Flinders Resistant Line (FRL). Gene expression data from the PFC of FSL/FRL animals (GEO accession no. GSE20388) were used to guide mRNA target selection. Luciferase reporter assays were used to verify miRNA targets in vitro. RESULTS: We identified 23 miRNAs that were downregulated in the PFC of the FSL model compared with controls. Interestingly, one of the identified miRNAs (miR-101b) is highly conserved between rat and human and was recently found to be downregulated in the PFC of depressed suicide subjects. Using a combination of in silico and in vitro analyses, we found that miR-101b targets the neuronal glutamate transporter SLC1A1 (also known as EAAC1 or EAAT3). Accordingly, both mRNA and protein levels of SLC1A1 were found to be upregulated in the PFC of the FSL model. CONCLUSIONS: Besides providing a list of novel miRNAs associated with depression-like states, this preclinical study replicated the human association of miR-101 with depression. In addition, since one of the targets of miR-101b appears to be a glutamate transporter, our preclinical data support the hypothesis of a glutamatergic dysregulation being implicated in the etiology of depression.

Neuropeptide Y-stimulated [(35) S]GTPγs functional binding is reduced in the hippocampus after kainate-induced seizures in mice.

Kainate-induced seizures constitute a model of temporal lobe epilepsy where prominent changes are observed in the hippocampal neuropeptide Y (NPY) system. However, little is known about the functional state and signal transduction of the NPY receptor population resulting from kainate exposure. Thus, in this study, we explored functional NPY receptor activity in the mouse hippocampus and neocortex after kainate-induced seizures using NPY-stimulated [(35) S]GTPγS binding. Moreover, we also studied levels of [(125) I]-peptide YY (PYY) binding and NPY, Y1, Y2, and Y5 receptor mRNA in these kainate-treated mice. Functional NPY binding was unchanged up to 12 h post-kainate, but decreased significantly in all hippocampal regions after 24 h and 1 week. Similarly, a decrease in [(125) I]-PYY binding was found in the dentate gyrus (DG) 1 week post-kainate. However, at 2 h, 6 h, and 12 h, [(125) I]-PYY binding was increased in all regions, and in the CA1 also at 24 h post-kainate. NPY mRNA levels were prominently increased in hippocampal regions, reaching maximum at 12 and 24 h. Y1 and Y5 mRNA levels were lowered in the DG at 24 and 2 h, respectively, while Y2 mRNA levels were elevated at 24 h in the DG and CA3. This study confirms rat kainate studies by showing pronounced adaptive changes in the mouse hippocampus both with regard to NPY synthesis and NPY receptor synthesis and binding, which may contribute to regulating neuronal seizure susceptibility after kainate. However, the potential seizure-suppressant effects of increased NPY gene expression at late time points post-kainate could be attenuated by the novel finding of reduced NPY-receptor G-protein activation.

Synthesis and biological evaluation of Esaprazole analogues showing σ1 binding and neuroprotective properties in vitro.

Esaprazole, a molecule previously acknowledged to protect against stomach and intestinal ulcers was surprisingly discovered to have neuroprotective activities and σ1 binding in vitro. A highly diverse set of Esaprazole analogues 2-5 was prepared in order to increase blood-brain barrier penetration. The analogues showed a structure-activity relationship at the σ1 receptor closely matching already published pharmacophores. Many of the analogues were shown to have neuroprotective properties in two assays using primary cultures of cortical neurons exposed to glutamate and hydrogen peroxide. However, no apparent SAR for these two assays could be developed. Metabolic stability of the analogues were also investigated and the structure of R(1) had a significant bearing on the ADME properties of the compound resulting in two series of compounds. Compounds in which R(1) was a H or acyl group had good metabolic stability in RLM but poor BBB penetration, whereas compounds where R(1) was a cyclo- or bicyclo-alkyl group had poor metabolic stability but good BBB penetration.

4-iodophenyl isothiocyanate: a neuroprotective compound.

PURPOSE: Naturally occurring isothiocyanates (ITCs) are known to possess chemopreventive and neuroprotective properties. Our objective was to study the synthetic ITC 4-iodophenyl isothiocyanate (4-IPITC) in different models of neurodegeneration. METHODS: In vitro, we exposed primary cortical neurons to various insults such as excessive glutamate exposure, oxygen-glucose deprivation, oxidative stress and 1-methyl-phenylpyridinium (MPP+). In vivo, experimental autoimmune encephalomyelitis (EAE) was induced in dark agouti rats treated with 4-IPITC in 3 different concentrations (10, 20 and 40 mg/kg), orally for 28 days. In a Parkinson's model, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) was injected in mice pretreated with 4-IPITC (5 mg/kg, orally) for 1 week. Nest building behavior at day 1, 3 and 6 after MPTP injection was assessed along with dopamine and metabolites, and tyrosine hydroxylase (TH) staining on termination day 6. RESULTS: 4-IPITC successfully reduced cell death in all in vitro assays. Moreover, in two independent neurite outgrowth assays the compound showed neurotrophic properties. In the EAE study, 4-IPITC significantly delayed the day of onset and decreased the cumulative EAE score. Although the number of animals in this MPTP study was limited, 4-IPITC showed potential for dampening toxicity. CONCLUSIONS: Taken together, our in vitro findings suggest robust neuroprotective and neurotrophic properties of 4-IPITC, which was confirmed in two in vivo models of neurodegeneration.

Adeno-associated viral vector-induced overexpression of neuropeptide Y Y2 receptors in the hippocampus suppresses seizures.

Gene therapy using recombinant adeno-associated viral vectors overexpressing neuropeptide Y in the hippocampus exerts seizure-suppressant effects in rodent epilepsy models and is currently considered for clinical application in patients with intractable mesial temporal lobe epilepsy. Seizure suppression by neuropeptide Y in the hippocampus is predominantly mediated by Y2 receptors, which, together with neuropeptide Y, are upregulated after seizures as a compensatory mechanism. To explore whether such upregulation could prevent seizures, we overexpressed Y2 receptors in the hippocampus using recombinant adeno-associated viral vectors. In two temporal lobe epilepsy models, electrical kindling and kainate-induced seizures, vector-based transduction of Y2 receptor complementary DNA in the hippocampus of adult rats exerted seizure-suppressant effects. Simultaneous overexpression of Y2 and neuropeptide Y had a more pronounced seizure-suppressant effect. These results demonstrate that overexpression of Y2 receptors (alone or in combination with neuropeptide Y) could be an alternative strategy for epilepsy treatment.