A double-labelling procedure combining immunohistochemical staining with in situ hybridization using a radiolabelled cRNA probe was employed to demonstrate oestrogen receptor-like immunoreactivity and preproenkephalin-A mRNA in the medullary and spinal dorsal horn of female rats. Both markers labelled large numbers of neurons in the substantia gelatinosa and its trigeminal homologue. Many of these neurons were double-labelled, displaying both oestrogen receptor-like-immunoreactivity and preproenkephalin-A mRNA; cell counts showed that 40-60% of the of the oestrogen receptor-like-immunoreactive cells in the superficial laminae also were labelled for preproenkephalin-A mRNA, and that 60-70% of the preproenkephalin-A mRNA-labelled neurons in the same laminae displayed oestrogen receptor-like immunoreactivity. Previous studies have shown that oestrogen receptors can bind to the promoter region of the preproenkephalin-A gene, and studies on the hypothalamus have demonstrated that oestrogen regulates enkephalin expression in select neuronal populations. The present results demonstrate that enkephalinergic neurons in the superficial dorsal horn contain oestrogen receptors and suggest that oestrogen may play an important role in the modulation of sensory and nociceptive processing in the lower medulla and spinal cord.

Inhibitors of apoptosis proteins (IAPs) define a protein family with the ability to counteract cell death by the inhibition of different caspases activated during apoptosis. These proteins are present in different cells, however, the function and roles of IAPs in brain tissue are not fully understood. We report here that RIAP-2, the rat homologue of human cIAP-1/HIAP-2, is expressed in different areas of rat brain as shown by in situ hybridization and immunohistochemistry. Brain regions with relatively high expression of RIAP-2 mRNA included cortex, cerebellum and different subregions of rat hippocampus. Double labelling using a specific anti-RIAP antibody and markers for neurons and glial cells, showed that RIAP-2 is predominantly expressed by nerve cells. Kainic acid treatment, which induces seizures, transiently up-regulated RIAP-2 mRNA levels in cerebral cortex, in the CA1 and dentate gyrus regions of hippocampus, which returned to normal levels at 24 h. However in the CA3 region, RIAP-2 mRNA was decreased at 6 h following an early up-regulation. This region contains neurons particularly vulnerable to kainic acid induced cell degeneration. The decrease in RIAP-2 following kainic acid was also observed using immunohistochemistry. RIAP-2 protein did not colocalize with TUNEL labelling present in cells undergoing cell death. The results show that in the adult rat brain RIAP-2 is expressed mainly by neurons, and that the levels are regulated by kainic acid, which activates glutamate receptors. The decrease in RIAP-2 in specific neuronal populations may contribute to cell degeneration in vulnerable brain regions observed after kainic acid treatment.

In a great partnership, the Federation of European Neuroscience Societies (FENS) and the Hertie Foundation organized the FENS-Hertie 2022 Winter School on 'Neuro-immune interactions in health and disease'. The school selected 27 PhD students and 13 postdoctoral fellows from 20 countries and involved 14 faculty members experts in the field. The Winter School focused on a rising field of research, the interactions between the nervous and both innate and adaptive immune systems under pathological and physiological conditions. A fine-tuned neuro-immune crosstalk is fundamental for healthy development, while disrupted neuro-immune communication might play a role in neurodegeneration, neuroinflammation and aging. However, much is yet to be understood about the underlying mechanisms of these neuro-immune interactions in the healthy brain and under pathological scenarios. In addition to new findings in this emerging field, novel methodologies and animal models were presented to foment research on neuro-immunology. The FENS-Hertie 2022 Winter School provided an insightful knowledge exchange between students and faculty focusing on the latest discoveries in the biology of neuro-immune interactions while fostering great academic and professional opportunities for early-career neuroscientists from around the world.

Abuse of androgenic anabolic steroids can affect brain function leading to behavioural changes. In this study, the effects of the testosterone analogue, 19-nortestosterone, on rat neural stem cells was examined. The androgen receptor is expressed by cultured embryonic and adult neural stem cells, and is also present in the ventricular epithelium during development and in the adult brain in, among others, dentate gyrus. In neural stem cells stimulated with epidermal growth factor, nandrolone reduced cell proliferation, especially in adult ones. The decrease was abolished by flutamide, a receptor antagonist. Nandrolone also decreased the BrdU labelling of neural stem cells in the dentate gyrus, demonstrating an effect of the hormone on cell proliferation in vivo. The effect of nandrolone was observed with both female and male rats but it was more pronounced in pregnant rats, indicating an involvement of oestrogen in nandrolone action. Nandrolone also decreased the number of newly born neuronal cells in the dentate gyrus of male rats. The results show that nandrolone has important effects on the proliferation and differentiation of neural stem cells expressing the cognate androgen receptor. The data show that the use of nandrolone may severely affect the formation of neural stem cells and could therefore have long-term negative consequences in the brain.

Adolescence is a critical maturation period for human cognitive control and executive function. In this study, a large sample of adolescents (n=85) performed a reversal learning task during functional magnetic resonance imaging. We analyzed behavioral data using a reinforcement learning model to provide individually fitted parameters and imaging data with regard to reward prediction errors (PE). Following a model-based approach, we formed two groups depending on whether individuals tended to update expectations predominantly for the chosen stimulus or also for the unchosen one. These groups significantly differed in their problem behavior score obtained using the child behavior checklist (CBCL) and in a measure of their developmental stage. Imaging results showed that dorsolateral striatal areas covaried with PE. Participants who relied less on learning based on task structure showed less prefrontal activation compared with participants who relied more on task structure. An exploratory analysis revealed that PE-related activity was associated with pubertal development in prefrontal areas, insula and anterior cingulate. These findings support the hypothesis that the prefrontal cortex is implicated in mediating flexible goal-directed behavioral control.

Barh1/h2 genes encode two related homeobox transcription factors (B-H1 and B-H2) previously shown to play essential roles in the formation and specification of the distal leg segments and in retinal neurogenesis. Here we describe the restricted expression pattern of the B-H1/-H2 homeoprotein within the embryonic ventral nerve cord of Drosophila. We show that B-H1/-H2 are specifically expressed in a subset of dopaminergic neurons, namely the unpaired ventral midline dopaminergic neuron, and in a subpopulation of laterally projecting motoneurons, i.e. the five motoneurons forming the segmental nerve a (SNa) branch. Using the GAL4-UAS system we show that B-H1/-H2Gal4 in combination with a membrane-targeted enhanced green fluorescent protein reporter line provides a powerful genetic tool reproducibly to label SNa motoneuron projections and terminals at the periphery, and their dendritic tree in the ventral nerve cord. Thus, the highly restricted expression pattern of the B-H1/-H2 homeoproteins and notably the related Gal4 driver represent powerful genetic tools to identify and study genes that control axon guidance, synaptogenesis or dendritic arborization within a small subpopulation of motoneurons identifiable from embryogenesis to late larval stages. © The Authors (2006).

Administration of 17β-estradiol to ovariectomized rats increased the concentrations of galanin-like immunoreactivity (LI) in the hippocampal formation by 215% (P < 0.001) within 1 h. An increase of 125% (P < 0.05) was observed in the same brain region in the proestrous phase of a normal estrous cycle. Tamoxifen^® did not block the 17β-estradiol-induced increase in the concentration of galanin-LI but resulted in a 62% decrease in the hypothalamus within 1 h. In vivo microdialysis in the dorsal hippocampal formation showed a decrease of extracellular galanin-LI (P < 0.001) 1−2 h after treatment with 17β-estradiol, indicating a decreased release of galanin. For comparision, we studied the concentrations of neuropeptide Y, which were not influenced significantly in any of the regions studied. Taken together our results suggest that 17β-estradiol inhibits galanin release, presumably from noradrenergic nerve terminals, and primarily via a nongenomic/indirect action, not necessarily involving the classical nuclear receptors ER-α or ER-β. These rapid estrogen-induced changes in galanin release could influence transmitter signalling and plasticity in the hippocampal formation.

X chromosome-linked inhibitor of apoptosis protein (XIAP) is an anti-apoptotic protein enhancing cell survival. Brain-derived neurotrophic factor (BDNF) also promotes neuronal viability but the links between XIAP and BDNF have remained unclear. We show here that the overexpression of XIAP increases BDNF in transgenic mice and cultured rat hippocampal neurons, whereas downregulation of XIAP by silencing RNA decreased BDNF. XIAP also stimulated BDNF signaling, as shown by increased phosphorylation of the TrkB receptor and the downstream molecule, cAMP response element-binding protein. The mechanism involved nuclear factor-kappa B (NF-kappa B) activation and blocking of NF-kappa B signaling inhibited the increased activities of BDNF promoters I and IV by XIAP. In neuronal cultures XIAP also upregulated interleukin (IL)-6, which is an NF-kappa B-responsive gene. The addition of IL-6 elevated whereas incubation with IL-6-blocking antibodies reduced BDNF in the neurons. BDNF itself activated NF-kappa B in the neurons at higher concentrations. The data show that XIAP has trophic effects on hippocampal neurons by increasing BDNF and TrkB activity. The results reveal a cytokine network in the brain involving BDNF, IL-6 and XIAP interconnected via the NF-kappa B system.

Forebrain structures are necessary for the initiation of food intake and its coupling to energy expenditure. The cancer-related anorexia-cachexia syndrome is typified by a prolonged increase in metabolic rate resulting in body weight loss which, paradoxically, is accompanied by reduced food intake. The aim of the present work was to study the forebrain expression of Fos proteins as activation markers and thus to identify potential neurobiological mechanisms favouring catabolic processes or modulating food intake in rats suffering from cancer-related anorexia-cachexia. Neurons in forebrain structures showing most pronounced induction of Fos proteins were further identified neurochemically. To provoke anorexia-cachexia, cultured Morris hepatoma 7777 cells were injected subcutaneously in Buffalo rats. This resulted in a slowly growing tumour inducing ≈7% body weight loss and a 20% reduction in food intake when the tumour represented 1-2% of body mass. Anorexia-cachexia in these animals was found to be accompanied by Fos induction in several hypothalamic nuclei including the paraventricular and ventromedial hypothalamus, in the parastrial nucleus, the amygdala, the bed nucleus of the stria terminalis, ventral striatal structures and the piriform and somatosensory cortices. Neurochemical identification revealed that the vast majority of FosB-positive neurons in the nucleus accumbens, ventral caudate-putamen and other ventral striatal structures contained prodynorphin or proenkephalin mRNA. These findings indicate that forebrain structures that are part of neuronal networks modulating catabolic pathways and food ingestion are activated during tumour-associated anorexia-cachexia and may contribute to the lack of compensatory eating in response to weight loss characterizing this syndrome. © 2005 Federation of European Neuroscience Societies.

Cytokines act on the brain to induce fever and behavioural depression after infection. Although several mechanisms of cytokine-to-brain communication have been proposed, their physiological significance is unclear. We propose that behavioural depression is mediated by the vagus nerve activating limbic structures, while fever would primarily be due to humoral mechanisms affecting the preoptic area, including interleukin-6 (IL-6) action on the organum vasculosum of the laminae terminalis (OVLT) and induction of prostaglandins. This study assessed the effects of subdiaphragmatic vagotomy in rats on fever, behavioural depression, as measured by the social interaction test, and Fos expression in the brain. These responses were compared with induction of the prostaglandin-producing enzyme cyclooxygenase-2 and the transcription factor Stat3 that translocates after binding of IL-6. Vagotomy blocked behavioural depression after intraperitoneal injection of recombinant rat IL-1ß (25 µg/kg) or lipopolysaccharide (250 µg/kg, LPS) and prevented Fos expression in limbic structures and ventromedial preoptic area, but not in the OVLT. Fever was not affected by vagotomy, but associated with translocation of Stat3 in the OVLT and cyclooxygenase-2 induction around blood vessels. These results indicate that the recently proposed vagal link between the immune system and the brain activates limbic structures to induce behavioural depression after abdominal inflammation. Although the vagus might play a role in fever in response to low doses of LPS by activating the ventromedial preoptic area, it is likely to be overridden during more severe infection by action of circulating IL-6 on the OVLT or prostaglandins induced along blood vessels of the preoptic area.

Kainic acid induces excitotoxicity and nerve cell degeneration in vulnerable regions of rat brain, most markedly in hippocampus and amygdala. Part of the cell death following kainic acid is apoptotic as shown by caspase 3 activation and chromatin condensation. Here we have studied the regulation of pro- and anti-apoptotic proteins belonging to the Bcl-2 family in rat hippocampus and amygdala by kainic acid in relationship to ensuing neuronal death. The pro-apoptotic protein Bax was up-regulated in hippocampus 6 h after kainic acid administration. The increase in Bax was followed by the appearance of TdT-mediated dUTP nick end label ling-positive cells which were prominent at 24 h. Immunohistochemistry for active Bax revealed a punctated labelling of neurons in the CA3 and hilar regions of hippocampus as well as in amygdala. Double staining for NeuN, a marker for nerve cells, and TdT-mediated dUTP nick end labelling showed that mainly neurons undergo degeneration after kainic acid treatment. In contrast to Bax, the pro-apoptotic BH3-only Bcl-2 proteins Bim and Harakiri/DP5 were down-regulated by kainic acid. This was also observed for the anti-apoptotic proteins Bcl-x and Bcl-w. Immunoreactive Bcl-2 was up-regulated in hippocampus after kainic acid together with an increase in the phosphorylation of serine-87 in Bcl-2, suggesting a post-transcriptional modification of the protein. This was confirmed using immunoprecipitation of total Bcl-2 from hippocampus and amygdala which revealed an increase in serine-87 phospho-Bcl-2 after kainic acid. Inhibition of the c-jun N-terminal protein kinase pathway reduced both serine-87 phosphorylation and cell death after kainic acid. This indicates an important role of Bcl-2 phosphorylation in controlling neuronal death after kainic acid. In contrast to the situation in trophic factor-deprived neurons, no up-regulation of Bim or Harakiri/DP5 proteins occurred after kainic acid, suggesting alternative pathways for regulation of cell death in excitotoxicity The results indicate that not only the relative levels of Bcl-2 family proteins but also conformation changes and post-translational modifications contribute to neuronal death following kainic acid.

Members of the Bcl‐2 family are major regulators of cell death and survival. Bcl‐2 has been shown to heterodimerize with the death‐inducing protein Bax, but the mechanism of action of Bcl‐2 is not fully understood. Here we show, using the human NT‐2 neuronal cell line, that overexpression of Bcl‐2 leads to dramatic down‐regulation of the cysteine proteases ICH and CPP32/Yama, which are directly involved in cell death. In addition, the nuclear enzyme poly(ADP‐ribose) polymerase was cleaved in control cells but not in cells overexpressing Bcl‐2 following induction of apoptosis. The mRNA levels of ICH and CPP32/Yama were differentially affected by Bcl‐2 overexpression, suggesting both transcriptional and post‐transcriptional effects of the protein. These results demonstrate novel mechanisms of action of Bcl‐2 in influencing the expression of death effectors such as the cysteine proteases. The relative levels of Bcl‐2 and of various cysteine proteases ultimately determine survival and death of different cells, including neurons.

Hepatocyte growth factor-scatter factor (HGF) is expressed in different parts of the nervous system, and has been shown to exhibit neurotrophic activity. Here we show that c-Met, the receptor for HGF, is expressed in developing rat hippocampus, with the highest levels during the first postnatal weeks. To study the function of HGF, hippocampal neurons were prepared from embryonic rats and treated with different HGF concentrations. In these cultures, HGF increased the number of neurons expressing the 28-kDa calcium-binding protein (calbindin D) in a dose-dependent manner. The effect of HGF was larger than that observed with either brain-derived neurotrophic factor (BDNF) or neurotrophin-3 (NT-3), and cotreatment of the cultures with HGF and the neurotrophins was additive with respect to calbindin D neurons. Besides affecting the number of neurons, HGF significantly increased the degree of sprouting of calbindin D-positive neurons, suggesting an influence on neuronal maturation. BDNF and NT-3 stimulated neurite outgrowth of calbindin D neurons to a much smaller degree. In contrast to calbindin D neurons, HGF did not significantly increase the number of neurons immunoreactive with the neurotransmitter gamma-aminobutyric acid (GABA) in the hippocampal cultures. Immunohistochemical studies showed that c-Met-, calbindin D- and HGF-immunoreactive cells are all present in the dentate gyrus and partly colocalize within neurons. These results show that HGF acts on calbindin D-containing hippocampal neurons and increases their neurite outgrowth, suggesting that HGF plays an important role for the maturation and function of these neurons in the hippocampus.

Postsynaptic autophosphorylation of Ca2+/calmodulin-dependent protein kinase II (CaMKII) at Thr286/287 is crucial for the induction of long-term potentiation at many glutamatergic synapses, and has also been implicated in the persistence of synaptic potentiation. However, the availability of CaMKII phosphorylated at Thr286/287 at individual glutamatergic synapses in vivo is unclear. We used post-embedding immunogold labelling to quantitatively analyse the ultrastructural localization of CaMKII phosphorylated at Thr286/287 (pCaMKII) at synapses formed by presumed nociceptive and low-threshold mechanosensitive primary afferent nerve endings in laminae I-IV of rat spinal cord. Immunogold labelling was enriched in the postsynaptic densities of such synapses, consistent with observations in pre-embedding immunoperoxidase-stained dorsal horn. Presynaptic axoplasm also exhibited sparse immunogold labelling, in peptidergic terminals partly associated with dense core vesicles. Analysis of single or serial pCaMKII-immunolabelled sections indicated that the large majority of synapses formed either by presumed peptidergic or non-peptidergic nociceptive primary afferent terminals in laminae I-II of the spinal cord, or by presumed low-threshold mechanosensitive primary afferent terminals in laminae IIi-IV, contained pCaMKII in their postsynaptic density. However, the postsynaptic levels of pCaMKII immunolabelling at low-threshold primary afferent synapses were only approximately 50% of those at nociceptive synapses. These results suggest that constitutively autophosphorylated CaMKII in the postsynaptic density is a common characteristic of glutamatergic synapses, thus potentially contributing to maintenance of synaptic efficacy. Furthermore, pCaMKII appears to be differentially regulated between high- and low-threshold primary afferent synapses, possibly reflecting different susceptibility to synaptic plasticity between these afferent pathways.

Treatment of post-traumatic stress disorder is complicated by the presence of alcohol use disorder comorbidity. Little is known about the underlying brain mechanisms. We have recently shown, in mice, that the post-traumatic stress disorder-like phenotype is characterised by the increase and decrease in total dendritic number and length in the prelimbic and infralimbic areas of the medial prefrontal cortex, respectively. Here, we examined whether repeated ethanol exposure would exacerbate these changes and whether this would be associated with difficulty to extinguish passive avoidance behaviour, as an indicator of treatment resistance. We also analysed whether other known trauma-associated changes, like increased or decreased corticosterone and decreased brain-derived neurotrophic factor levels, would also be exacerbated. Male mice underwent trauma exposure (1.5-mA footshock), followed, 8 days later, by a conditioned place preference training with ethanol. Tests for fear sensitization, passive avoidance, anxiety-like behaviour, extinction acquisition and relapse susceptibility were used to assess behaviour changes. Plasma corticosterone and brain-derived neurotrophic factor levels and prefrontal dendritic changes were subsequently measured. Trauma-susceptible mice exposed to ethanol acquired a strong place preference and behaved differently from those not exposed to ethanol, with delayed avoidance extinction and higher avoidance relapse vulnerability. Ethanol potentiated trauma-associated dendritic changes in the prelimbic area and suppressed trauma-associated dendritic changes in the infralimbic area. However, ethanol had no effect on trauma-induced increased corticosterone and decreased brain-derived neurotrophic factor levels. These data suggest that the modification of prefrontal trauma-related changes, due to alcohol use, can characterise, and probably support, treatment-resistant post-traumatic stress disorder.

Treatment of post-traumatic stress disorder is complicated by the presence of alcohol use disorder comorbidity. Little is known about the underlying brain mechanisms. We have recently shown, in mice, that the post-traumatic stress disorder-like phenotype is characterised by the increase and decrease in total dendritic number and length in the prelimbic and infralimbic areas of the medial prefrontal cortex, respectively. Here, we examined whether repeated ethanol exposure would exacerbate these changes and whether this would be associated with difficulty to extinguish passive avoidance behaviour, as an indicator of treatment resistance. We also analysed whether other known trauma-associated changes, like increased or decreased corticosterone and decreased brain-derived neurotrophic factor levels, would also be exacerbated. Male mice underwent trauma exposure (1.5-mA footshock), followed, 8 days later, by a conditioned place preference training with ethanol. Tests for fear sensitization, passive avoidance, anxiety-like behaviour, extinction acquisition and relapse susceptibility were used to assess behaviour changes. Plasma corticosterone and brain-derived neurotrophic factor levels and prefrontal dendritic changes were subsequently measured. Trauma-susceptible mice exposed to ethanol acquired a strong place preference and behaved differently from those not exposed to ethanol, with delayed avoidance extinction and higher avoidance relapse vulnerability. Ethanol potentiated trauma-associated dendritic changes in the prelimbic area and suppressed trauma-associated dendritic changes in the infralimbic area. However, ethanol had no effect on trauma-induced increased corticosterone and decreased brain-derived neurotrophic factor levels. These data suggest that the modification of prefrontal trauma-related changes, due to alcohol use, can characterise, and probably support, treatment-resistant post-traumatic stress disorder.

Peroxisome proliferator-activated receptor gamma coactivator-1 (PGC-1) is a transcriptional coactivator involved in the regulation of mitochondrial biogenesis and cell defense. The functions of PGC-1 in physiology of brain mitochondria are, however, not fully understood. To address this we have studied wild-type and transgenic mice with a two-fold overexpression of PGC-1 in brain neurons. Data showed that the relative number and basal respiration of brain mitochondria were increased in PGC-1 transgenic mice compared with wild-type mitochondria. These changes occurred concomitantly with altered levels of proteins involved in oxidative phosphorylation (OXPHOS) as studied by proteomic analyses and immunoblottings. Cultured hippocampal neurons from PGC-1 transgenic mice were more resistant to cell degeneration induced by the glutamate receptor agonist kainic acid. In vivo kainic acid induced excitotoxic cell death in the hippocampus at 48h in wild-type mice but significantly less so in PGC-1 transgenic mice. However, at later time points cell degeneration was also evident in the transgenic mouse hippocampus, indicating that PGC-1 overexpression can induce a delay in cell death. Immunoblotting showed that X-linked inhibitor of apoptosis protein (XIAP) was increased in PGC-1 transgenic hippocampus with no significant changes in Bcl-2 or Bcl-X. Collectively, these results show that PGC-1 overexpression contributes to enhanced neuronal viability by stimulating mitochondria number and respiration and increasing levels of OXPHOS proteins and the anti-apoptotic protein XIAP.

Increased levels of glutamate causing excitotoxic damage accompany neurological disorders such as ischemia/stroke, epilepsy and some neurodegenerative diseases. Cyclin-dependent kinase-5 (Cdk5) is important for synaptic plasticity and is deregulated in neurodegenerative diseases. However, the mechanisms by which kainic acid (KA)-induced excitotoxic damage involves Cdk5 in neuronal injury are not fully understood. In this work, we have thus studied involvement of Cdk5 in the KA-mediated degeneration of glutamatergic synapses in the rat hippocampus. KA induced degeneration of mossy fiber synapses and decreased glutamate receptor (GluR)6/7 and post-synaptic density protein 95 (PSD95) levels in rat hippocampus in vivo after intraventricular injection of KA. KA also increased the cleavage of Cdk5 regulatory protein p35, and Cdk5 phosphorylation in the hippocampus at 12 h after treatment. Studies with hippocampal neurons in vitro showed a rapid decline in GluR6/7 and PSD95 levels after KA treatment with the breakdown of p35 protein and phosphorylation of Cdk5. These changes depended on an increase in calcium as shown by the chelators 1,2-bis(o-aminophenoxy)ethane-N,N,N?',N'-tetraacetic acid acetoxymethyl ester (BAPTA-AM) and glycol-bis (2-aminoethylether)-N,N,N?',N?'-tetra-acetic acid. Inhibition of Cdk5 using roscovitine or employing dominant-negative Cdk5 and Cdk5 silencing RNA constructs counteracted the decreases in GluR6/7 and PSD95 levels induced by KA in hippocampal neurons. The dominant-negative Cdk5 was also able to decrease neuronal degeneration induced by KA in cultured neurons. The results show that Cdk5 is essentially involved in the KA-mediated alterations in synaptic proteins and in cell degeneration in hippocampal neurons after an excitotoxic injury. Inhibition of pathways activated by Cdk5 may be beneficial for treatment of synaptic degeneration and excitotoxicity observed in various brain diseases.

Thioredoxins are a class of small redox-regulating proteins that have been implicated in the control of various aspects of cellular functions and seem to be one of the key regulators of signalling in the cellular responses to various stresses. Thioredoxin-2 (Trx2) is a novel mammalian thioredoxin which, in contrast to previously known cytosolic thioredoxin (Trx1), has been localized to the mitochondria. Trx2 is abundantly expressed in skeletal muscle, heart and adrenal gland, as well as in some other peripheral tissues with high metabolic activity. Using in situ hybridization and immunohistochemistry, we have studied the distribution and regulation of Trx2 expression in the rat brain. Trx2 mRNA and protein are highly expressed in the neurons in several brain regions, including the olfactory bulb, frontal cortex, hippocampus, some hypothalamic and thalamic nuclei, cerebellum and numerous brainstem nuclei. In addition, the Trx2 mRNA expression in paraventricular hypothalamic nucleus and reticular thalamic nucleus was found to be sensitive to peripheral glucocorticoids, as dexamethasone treatment caused significant elevation of Trx2 mRNA level in this area. No changes in other brain areas were observed after dexamethasone treatment. These findings implicate a significant regulatory and/or protective function of Trx2 in the nervous system.

Recent human behavioral studies have shown semantic and/or lexical processing for stimuli presented below the auditory perceptionthreshold. Here, we investigated electroencephalographic responses to words, pseudo-words and complex sounds, in conditionswhere phonological and lexical categorizations were behaviorally successful (categorized stimuli) or unsuccessful(uncategorized stimuli). Data showed a greater decrease in low-beta power at left-hemisphere temporal electrodes for categorizednon-lexical sounds (complex sounds and pseudo-words) than for categorized lexical sounds (words), consistent with the signatureof a failure in lexical access. Similar differences between lexical and non-lexical sounds were observed for uncategorized stimuli,although these stimuli did not yield evoked potentials or theta activity. The results of the present study suggest that behaviorallyuncategorized stimuli were processed at the lexical level, and provide evidence of the neural bases of the results observed in previousbehavioral studies investigating auditory perception in the absence of stimulus awareness.

Pituitary adenylate cyclase-activating polypeptide (PACAP) is a member of the vasointestinal polypeptide gene family for which neurotrophic activity has been postulated. PACAP mRNA is expressed in the developing and adult hippocampus, which is the principal target region of septal cholinergic neurons. We therefore studied the effects of PACAP on septal cholinergic neurons. In primary cultures from septum of embryonic and postnatal rats, PACAP increased the number of neurons immunohistochemically stained for the low-affinity nerve growth factor (NGF) receptor p75 and for the enzyme choline acetyltransferase (ChAT). PACAP also caused a corresponding increase in ChAT activity. In comparison, NGF had a greater effect than PACAP on the number of p75- and ChAT-positive neurons in these cultures. In vivo, following fimbria fornix transection, the number of immunohistochemically stained septal cholinergic neurons fell significantly to 18% in rats given continuous intracerebroventricular infusion of vehicle, whereas in rats given NGF the number of these neurons did not differ significantly from unoperated controls. In PACAP-treated rats the number was 48% of unoperated values, which represented a significant increase compared with vehicle-treated rats and a significant decrease compared with NGF-treated rats or unoperated controls. Double-staining experiments revealed that most ChAT-positive neurons in rat medial septum also express PACAP receptor 1. Together the results show that PACAP promotes the survival of septal cholinergic neurons in vitro, and after injury in vivo, suggesting that PACAP acts as a neurotrophic factor influencing the development and maintenance of these neurons.

Noise, ototoxic substances and various genetic factors are common causes of profound hearing loss. Cochlear implants can often restore hearing in these cases, but only if a sufficient number of responsive auditory nerve fibers remain. Over time, these nerve fibers degenerate in the damaged ear, and it is therefore important to establish factors that control neuronal survival and maintain neural excitability. Recent studies show that neuregulins and their receptors are important for survival and proper targeting of neurons in the developing inner ear. A role for neuregulins as maintainers of the neuronal population in the mature inner ear was therefore hypothesized. Here, this hypothesis was directly tested by chronic local application of substances that block neuregulin receptors. Using auditory brainstem response measurements, we demonstrate that such receptor block leads to a progressive hearing impairment that develops over the course of weeks. This impairment occurs despite a normal number of auditory neurons and preserved outer hair cell function. Real-time quantitative reverse transcriptase-polymerase chain reaction shows alterations in neurotrophin-3 expression, suggesting that this growth factor participates in regulating cochlear sensitivity. The present work demonstrates the critical importance of neuregulin/erbB signaling in long-term functional regulation in the mature guinea pig hearing organ.

We demonstrate that X chromosome-linked inhibitor of apoptosis protein (XIAP) counteracts oxidative stress in two essentially different disease-related models of brain injury, hypoxia-ischemia and irradiation, as judged by lower expression of nitrotyrosine (5-fold) and 4-hydroxy-2-nonenal (10-fold) in XIAP-overexpressing compared with wild-type mice. XIAP overexpression induced up-regulation of at least three antioxidants residing in mitochondria, superoxide dismutase 2, thioredoxin 2 and lysine oxoglutarate reductase. Cytochrome c release from mitochondria was reduced in XIAP-overexpressing mice. Hence, in addition to blocking caspases, XIAP can regulate reactive oxygen species in the brain, at least partly through up-regulation of mitochondrial antioxidants. XIAP-induced prevention of oxidative stress was not secondary to tissue protection because although XIAP overexpression provides tissue protection after hypoxia-ischemia, it does not prevent tissue loss after irradiation. This is a previously unknown role of XIAP and may provide the basis for development of novel protective strategies for both acute and chronic neurodegenerative diseases, where oxidative stress is an integral component of the injury mechanisms involved.

Change in linguistic prosody generates a mismatch negativity response (MMN), indicating neural representation of linguistic prosody, while change in affective prosody generates a positive response (P3a), reflecting its motivational salience. However, the neural response to concurrent affective and linguistic prosody is unknown. The present paper investigates the integration of these two prosodic features in the brain by examining the neural response to separate and concurrent processing by electroencephalography (EEG). A spoken pair of Swedish words-[|f amp; x251; MODIFIER LETTER TRIANGULAR COLONsen] phase and [|f amp; x251;amp; x300;MODIFIER LETTER TRIANGULAR COLONsen] damn-that differed in emotional semantics due to linguistic prosody was presented to 16 subjects in an angry and neutral affective prosody using a passive auditory oddball paradigm. Acoustically matched pseudowords-[|v amp; x251; MODIFIER LETTER TRIANGULAR COLONsem] and [|v amp; x251;amp; x300;MODIFIER LETTER TRIANGULAR COLONsem]-were used as controls. Following the constructionist concept of emotions, accentuating the conceptualization of emotions based on language, it was hypothesized that concurrent affective and linguistic prosody with the same valence-angry [|f amp; x251;amp; x300;MODIFIER LETTER TRIANGULAR COLONsen] damn-would elicit a unique late EEG signature, reflecting the temporal integration of affective voice with emotional semantics of prosodic origin. In accordance, linguistic prosody elicited an MMN at 300-350 ms, and affective prosody evoked a P3a at 350-400 ms, irrespective of semantics. Beyond these responses, concurrent affective and linguistic prosody evoked a late positive component (LPC) at 820-870 ms in frontal areas, indicating the conceptualization of affective prosody based on linguistic prosody. This study provides evidence that the brain does not only distinguish between these two functions of prosody but also integrates them based on language and experience.