Sex-related differences of cAMP-specific PDE4B3 mRNA in oligodendrocytes following systemic inflammation

Sex-related differences have been observed in the incidence and severity of several neurological diseases and in sepsis in humans. Cyclic adenosine monophosphate (cAMP) has been shown to play an important role in modulating the inflammatory environment during neuroinflammation and importantly in protecting myelin from excitotoxic cell death. Considering the sexual dimorphism in the functional properties of oligodendrocytes and the importance of a systemic inflammation in the progression of multiple sclerosis, we focused on identifying possible sex-related differences in the alterations previously reported for the two phosphodiesterase4B (PDE4B) splice-variants (PDE4B2 and PDE4B3) mRNA expression during innate neuroinflammation. PDE4A, PDE4B, and PDE4D are present in oligodendrocytes and we have previously reported that PDE4B3 mRNA is readily expressed in both oligodendrocytes and neurons. In this study, we analyzed the influence of an intraperitoneal lipopolysaccharide injection on the distribution pattern and expression levels of the PDE4B mRNA splicing variants in both male and female mice brains. Clear differences were observed in PDE4B2 and PDE4B3 mRNA expression levels in males compared with females in a time-dependent manner. Furthermore, we observed that the clear downregulation of PDE4B3 mRNA was reflected in a lower percentage of oligodendrocytes positive for this transcript which correlated with a decrease in inducible cAMP early repressor expression in female corpus callosum. © 2012 Wiley Periodicals, Inc.Grant sponsor: Spanish Ministerio de Educación y Ciencia; Grant number: SAF2006-10243; Grant sponsor: Ministerio de Ciencia e Innovación; Grant numbers: SAF 2009-11052, PI-10/01874; Grant sponsor: Generalitat de Catalunya; Grant number: SGR2009/220; Grant sponsor: FEDER Funds (European Union).Peer Reviewe

Possible Correlation between Cholinergic System Alterations and Neuro/Inflammation in Multiple Sclerosis

Multiple sclerosis (MS) is an autoimmune and demyelinating disease of the central nervous system. Although the etiology of MS is still unknown, both genetic and environmental factors contribute to the pathogenesis of the disease. Acetylcholine participates in the modulation of central and peripheral inflammation. The cells of the immune system, as well as microglia, astrocytes and oligodendrocytes express cholinergic markers and receptors of muscarinic and nicotinic type. The role played by acetylcholine in MS has been recently investigated. In the present review, we summarize the evidence indicating the cholinergic dysfunction in serum and cerebrospinal fluid of relapsing–remitting (RR)‐MS patients and in the brains of the MS animal model experimental autoimmune encephalomyelitis (EAE). The correlation between the increased activity of the cholinergic hydrolyzing enzymes acetylcholinesterase and butyrylcholinesterase, the reduced levels of acetylcholine and the increase of pro‐inflammatory cytokines production were recently described in immune cells of MS patients. Moreover, the genetic polymorphisms for both hydrolyzing enzymes and the possible correlation with the altered levels of their enzymatic activity have been also reported. Finally, the changes in cholinergic markers expression in the central nervous system of EAE mice in peak and chronic phases suggest the involvement of the acetylcholine also in neuro‐inflammatory processes

Control of serotonergic neurons in rat brain by dopaminergic receptors outside the dorsal raphe nucleus

We studied the control of dorsal raphe (DR) serotonergic neurons by dopaminergic transmission in rat brain using microdialysis and single unit extracellular recordings. Apomorphine (0.5–3.0 mg/kg s.c.) and quinpirole (0.5 mg/kg s.c.) increased serotonin (5-HT) output in the DR and (only apomorphine) in striatum. These effects were antagonized by 0.3 mg/kg s.c. SCH 23390 (in DR and striatum) and 1 mg/kg s.c. raclopride (in DR). 5-HT1A receptor blockade potentiated the 5-HT increase produced by apomorphine in the DR. Apomorphine (50–400 µg/kg i.v.) increased the firing rate of most 5-HT neurons, an effect prevented by SCH 23390 and raclopride. Quinpirole (40–160 µg/kg i.v.) also enhanced the firing rate of 5-HT neurons. When applied in the DR, neither drug increased the 5-HT output in the DR or striatum. Likewise, micropressure injection of quinpirole (0.2–8 pmol) failed to increase the firing rate of 5-HT neurons. In situ hybridization showed that the dopamine (DA) D2 receptor transcript was almost absent in the DR and abundant in the substantia nigra (SN) and the periaqueductal grey matter (PAG). Using dual probe microdialysis, the application of tetrodotoxin or apomorphine in SN significantly increased the DR 5-HT output. Thus, the discrepancy between local and systemic effects of dopaminergic agonists and the absence of DA D2 receptor transcript in 5-HT neurons suggest that DA D2 receptors outside the DR control serotonergic activity.Peer reviewe

Galanin (1-15) enhances the behavioral effects of fluoxetine in the forced swimming test: a new therapeutic strategy against depression

The selective serotonergic (5- HT) reuptake inhibitors, including Fluoxetine (FLX), are the most commonly used for treatment of major depression. However, the understanding of the mechanism of action of FLX beyond its effect of elevating 5-HT is limited. The interaction between 5-HT system and neuropeptides signaling could be a key aspect. The neuropeptide Galanin(1-15) [GAL(1-15)], induced a strong depression-like and anxiogenic-like effects in the forced swimming test (FST), the tail suspension test, the open field and the light/dark test. The GALR1-GALR2 heteroreceptor complexes in the dorsal hippocampus and in the dorsal raphe were involved in these effects. We have analyzed the effect of GAL(1–15) on FLX-mediated responses in the FST. We tested the involvement of GALR in the GAL(1–15) effect with the selective GALR2 antagonist M871 and using siRNA GALR2 or GALR1 knockdown rats. Groups of rats received three injections of sc FLX(2.5mg/Kg) or FLX(10mg/Kg) and a single icv injection of a threshold dose of GAL(1-15)(1nmol) 15 minutes before the FST. In a second set of experiments, we determined the involvement of GALR1 and GALR2 in the effect of GAL(1-15) on FLX-mediated action. Groups of rats received three injections of sc FLX(10mg/kg), a single icv injection of GAL(1-15) (1nmol) and the GALR2 antagonist M871 (3nmol) icv alone or in combination. Also, in siRNA GALR1 or GALR2 knockdown rats we coadministered FLX(10mg/Kg) and GAL(1-15)(1nmol). The coadministration of sc FLX(2.5mg/Kg) and icv injection of GAL(1-15)(1nmol) induced antidepressant-like effects with a significant decrease in the immobility (p<0.05). Moreover, an increase in the swimming time (p <0.05) was also observed. The strong enhancement by GAL(1-15) of the antidepressant-like effects mediated by FLX was validated using the effective dose of FLX 10mg/kg. Icv GAL(1-15) significantly decreased the immobility time induced by the effective dose of FLX(10mg/kg) by 50% in the FST (p<0.05). Moreover, an increase of the swimming time by about 40% versus FLX(10mg/kg) group was also observed (p<0.01). The GALR2 antagonist M871 3nmol significantly blocked the GAL(1–15)-induced reduction of the immobility time (p<0.05), and increase in the swimming time (p<0.01) found after coadministration of icv injection of GAL(1-15) and sc FLX(10mg/kg) in the FST. The coadministration of sc FLX(10mg/kg) and icv injection of GAL(1-15) in siRNA GALR1 or GALR2 knockdown animals did not produce a further reduction of the immobility time and a further increase in the swimming time compared to FLX alone. In the current study we describe for the first time that GAL(1-15) enhances the antidepressant-like effects induced by FLX in the FST. Indications were also obtained for the involvement of a GALR1/GALR2 heteroreceptor complex in the GAL (1-15)-mediated actions based on the use of the specific GALR2 antagonist M871 and icv injections of GALR1 siRNA or GALR2 siRNA producing a reduction of GALR1 or GALR2, respectively. The results open up the possibility to use GAL(1-15) as for a combination therapy with FLX as a novel strategy for treatment of depression. This work was supported by grants awarded by Spanish Ministry of Economy (SAF2016-79008-P),Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Entacapone potentiates the long-duration response but does not normalize levodopa-induced molecular changes

El pdf del artículo es el manuscrito de autor.Coadministration of entacapone with levodopa attenuates motor complications in experimental models of Parkinson's disease. The mechanisms underlying entacapone effects are unknown. We investigated the effect of entacapone, on: long-duration response (LDR) to levodopa, levodopa-induced postsynaptic pharmacodynamic mechanisms and molecular changes in hemiparkinsonian rats. 6-Hydroxydopamine-unilaterally lesioned rats were treated with levodopa (25 mg/kg) + vehicle; levodopa + entacapone (30 mg/kg) or saline, twice daily for 22 days. The LDR and the apomorphine-induced rotations were measured. In situ hybridization was performed measuring the expression of striatal preproenkephalin, preprodynorphin and dopamine D-3 receptor mRNAs, subthalamic cytochrome oxidase mRNA and nigral glutamic acid decarboxylase mRNA. Entacapone potentiated the LDR but did not modify either the apomorphine-induced rotational behavior or the molecular changes. Our results suggest that the effects of entacapone on levodopa-induced motor response are not mediated by postsynaptic mechanisms and that administration of entacapone is not able to normalize the molecular alterations induced by levodopa in the basal ganglia.This work was supported by an unrestricted grant from Novartis-Orion Pharma (Barcelona, Spain). JAO serves as external adviser for Novartis Pharmaceutical (Barcelona, Spain). EA is partially financed by the program: Ayudas para Contratos de Apoyo a la Investigación en el Sistema Nacional de Salud from the Ministerio de Sanidad y Consumo of the Spanish Government.Peer reviewe

The human area postrema and other nuclei related to the emetic reflex express cAMP phosphodiesterases 4B and 4D

Phosphodiesterase 4 (PDE4) inhibitors, i.e. rolipram, are being extensively investigated as therapeutic agents in several diseases. Emesis is one of the most common side effects of PDE4 inhibitors. Given the fact that the area postrema is considered the chemoreceptor trigger zone for vomiting, the present study investigates the regional distribution and cellular localization of the four gene transcripts of the PDE4 subfamily (PDE4A, PDE4B, PDE4C and PDE4D) in human brainstem. In situ hybridization histochemistry was used to locate the mRNA distribution of the four PDE4 subfamilies in the area postrema and related nuclei of human postmortem brainstem. We have found that in the brainstem PDE4B and PDE4D mRNA expression is abundant and distributed not only in neuronal cells, but also in glial cells, and on blood vessels. The hybridization signals for PDE4B and PDE4D mRNAs in the area postrema were stronger than those in any other nuclei in the brainstem. They were also found in vomiting-related nuclei such as the nucleus of the solitary tract and the dorsal vagal motor nucleus. These findings suggest that cAMP signaling modification in the area postrema could mediate the emetic effects of PDE4 inhibitors in human brainstem.This work was supported by grants from Ministerio de Educación y Ciencia and Fondo Europeo de Desarrollo Regional (SAF2006-10243). F.M. was on sabbatical leave from Hirosaki University School of Medicine. S.P.-T. was recipient of a predoctoral fellowship from CIRIT (Generalitat de Catalunya).Peer Reviewe

Ikaros-1 couples cell cycle arrest of late striatal precursors with neurogenesis of enkephalinergic neurons.

During central nervous system development, several transcription factors regulate the differentiation of progenitor cells to postmitotic neurons. Here we describe a novel role for Ikaros-1 in the generation of late-born striatal neurons. Our results show that Ikaros-1 is expressed in the boundary of the striatal germinal zone (GZ)/mantle zone (MZ), where it induces cell cycle arrest of neural progenitors by up-regulation of the cyclin-dependent kinase inhibitor (CDKi) p21(Cip1/Waf1). This effect is coupled with the neuronal differentiation of late precursors, which in turn is critical for the second wave of striatal neurogenesis that gives rise to matrix neurons. Consistently, Ikaros(-/-) mice had fewer striatal projecting neurons and, in particular, enkephalin (ENK)-positive neurons. In addition, overexpression of Ikaros-1 in primary striatal cultures increases the number of calbindin- and ENK-positive neurons. Our results also show that Ikaros-1 acts downstream of the Dlx family of transcription factors, insofar as its expression is lost in Dlx1/2 double knockout mice. However, we demonstrate that Ikaros-1 and Ebf-1 independently regulate the final determination of the two populations of striatal projection neurons of the matrix compartment, ENK- and substance P-positive neurons. In conclusion, our findings identify Ikaros-1 as a modulator of cell cycle exit of neural progenitors that gives rise to the neurogenesis of ENK-positive striatal neurons.We thank M.T. Mun ̃oz, A. Lo ́pez, T. Gil, and M. Bonete for technical support and Dr. Maria Calvo and Anna Bosch from the confocal microscopy unit at the Serveis Cientı ́fico-Te`cnics (Universitat de Barcelona) for their sup-port and advice on confocal techniques. We also thank Dr.K. Campbell for providing Dlx5/6Cre-IRES-EGFP trans-genic mice, Dr. Rudolf Grosschedl for Ebf1–/– mice, and Dr.Susan Winandy for Ikaros constructs. We are also very grateful to Robin Rycroft for the English language revisionS

Chronic effects of corticosterone on GIRK1-3 subunits and 5-HT1A receptor expression in rat brain and their reversal by concurrent fluoxetine treatment

El pdf del artículo es el manuscrito revisado de autor.-- et al.Dysregulation of the serotonergic system and abnormalities of the hypothalamic-pituitary-adrenal axis have been demonstrated in major depression. Animal studies indicate that 5-HT1A receptor expression may be reduced by long-term administration of corticosterone. However, similar studies on the regulation of GIRK channels, one of the most important effectors of the neuronal 5-HT1A receptor, are limited. In order to address these issues, slow-release corticosterone pellets were implanted subcutaneously to adrenal intact male rats (200mg pellets, 35 days release). Starting on day 15, animals were treated for 21 days with fluoxetine (5mg/kg/day, i.p.), or vehicle. Using in situ hybridization histochemistry and receptor autoradiography, we found that chronic corticosterone treatment was accompanied by a significant decrease on the mRNAs coding for mineralocorticoid receptors in hippocampal areas. Under these conditions, 5-HT1A receptor mRNA expression decreased in dorsal raphe nucleus and dentate gyrus. However, 5-HT1A receptor levels, as measured by [(3)H]-8-OH-DPAT binding, diminished significantly only in dentate gyrus. It is noteworthy that chronic treatment with fluoxetine reversed the alterations on 5-HT1A receptor mRNA levels only in dorsal raphe. Finally, chronic corticosterone treatment produced an increase on the mRNA coding for the GIRK2 subunit in several hypothalamic and thalamic areas, which was reversed by fluoxetine. Measurements of cell density and volume of the granular layer of the dentate gyrus did not reveal significant changes after corticosterone or corticosterone plus fluoxetine treatments. These data are relevant for a better understanding of the differential regulation of pre- and postsynaptic 5-HT1A receptors by corticosterone flattened rhythm. Copyright 2012 Elsevier B.V. and ECNP. All rights reserved.This work was supported by grants SAF2004-02784 and SAF-2006-10243 from the Spanish Ministry of Science, grants S-PE08UN29 and IT-332-10 from the Basque Government, grant 2009SGR220 from the Catalan Government and the Instituto de Salud Carlos III, Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM) and Centro de Investigación Biomédica en Enfermedades Neurodegenerativas (CIBERNED). Laura Saenz del Burgo and Mario Montaña were recipients of fellowship from the Basque Government and from the UPV/EHU respectively.Peer Reviewe