| 1. |
- Adori, Csaba, et al.
(författare)
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Critical role of somatostatin receptor 2 in the vulnerability of the central noradrenergic system : new aspects on Alzheimer's disease
- 2015
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Ingår i: Acta Neuropathologica. - : Springer Science and Business Media LLC. - 0001-6322 .- 1432-0533. ; 129:4, s. 541-563
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Tidskriftsartikel (refereegranskat)abstract
- Alzheimer's disease and other age-related neurodegenerative disorders are associated with deterioration of the noradrenergic locus coeruleus (LC), a probable trigger for mood and memory dysfunction. LC noradrenergic neurons exhibit particularly high levels of somatostatin binding sites. This is noteworthy since cortical and hypothalamic somatostatin content is reduced in neurodegenerative pathologies. Yet a possible role of a somatostatin signal deficit in the maintenance of noradrenergic projections remains unknown. Here, we deployed tissue microarrays, immunohistochemistry, quantitative morphometry and mRNA profiling in a cohort of Alzheimer's and age-matched control brains in combination with genetic models of somatostatin receptor deficiency to establish causality between defunct somatostatin signalling and noradrenergic neurodegeneration. In Alzheimer's disease, we found significantly reduced somatostatin protein expression in the temporal cortex, with aberrant clustering and bulging of tyrosine hydroxylase-immunoreactive afferents. As such, somatostatin receptor 2 (SSTR2) mRNA was highly expressed in the human LC, with its levels significantly decreasing from Braak stages III/IV and onwards, i.e., a process preceding advanced Alzheimer's pathology. The loss of SSTR2 transcripts in the LC neurons appeared selective, since tyrosine hydroxylase, dopamine beta-hydroxylase, galanin or galanin receptor 3 mRNAs remained unchanged. We modeled these pathogenic changes in Sstr2 (-/-) mice and, unlike in Sstr1 (-/-) or Sstr4 (-/-) genotypes, they showed selective, global and progressive degeneration of their central noradrenergic projections. However, neuronal perikarya in the LC were found intact until late adulthood (< 8 months) in Sstr2 (-/-) mice. In contrast, the noradrenergic neurons in the superior cervical ganglion lacked SSTR2 and, as expected, the sympathetic innervation of the head region did not show any signs of degeneration. Our results indicate that SSTR2-mediated signaling is integral to the maintenance of central noradrenergic projections at the system level, and that early loss of somatostatin receptor 2 function may be associated with the selective vulnerability of the noradrenergic system in Alzheimer's disease.
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| 2. |
- Adori, Csaba, et al.
(författare)
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Disorganization and degeneration of liver sympathetic innervations in nonalcoholic fatty liver disease revealed by 3D imaging
- 2021
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Ingår i: Science Advances. - : American Association for the Advancement of Science (AAAS). - 2375-2548. ; 7:30
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Tidskriftsartikel (refereegranskat)abstract
- Hepatic nerves have a complex role in synchronizing liver metabolism. Here, we used three-dimensional (3D) immunoimaging to explore the integrity of the hepatic nervous system in experimental and human nonalcoholic fatty liver disease (NAFLD). We demonstrate parallel signs of mild degeneration and axonal sprouting of sympathetic innervations in early stages of experimental NAFLD and a collapse of sympathetic arborization in steatohepatitis. Human fatty livers display a similar pattern of sympathetic nerve degeneration, correlating with the severity of NAFLD pathology. We show that chronic sympathetic hyperexcitation is a key factor in the axonal degeneration, here genetically phenocopied in mice deficient of the Rac-1 activator Vav3. In experimental steatohepatitis, 3D imaging reveals a severe portal vein contraction, spatially correlated with the extension of the remaining nerves around the portal vein, enlightening a potential intrahepatic neuronal mechanism of portal hypertension. These fundamental alterations in liver innervation and vasculature uncover previously unidentified neuronal components in NAFLD pathomechanisms.
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| 3. |
- Adori, Csaba, et al.
(författare)
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Exploring the role of neuropeptide S in the regulation of arousal : a functional anatomical study
- 2016
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Ingår i: Brain Structure and Function. - : Springer. - 1863-2653 .- 1863-2661. ; 221:7, s. 3521-3546
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Tidskriftsartikel (refereegranskat)abstract
- Neuropeptide S (NPS) is a regulatory peptide expressed by limited number of neurons in the brainstem. The simultaneous anxiolytic and arousal-promoting effect of NPS suggests an involvement in mood control and vigilance, making the NPS-NPS receptor system an interesting potential drug target. Here we examined, in detail, the distribution of NPS-immunoreactive (IR) fiber arborizations in brain regions of rat known to be involved in the regulation of sleep and arousal. Such nerve terminals were frequently apposed to GABAergic/galaninergic neurons in the ventro-lateral preoptic area (VLPO) and to tyrosine hydroxylase-IR neurons in all hypothalamic/thalamic dopamine cell groups. Then we applied the single platform-on-water (mainly REM) sleep deprivation method to study the functional role of NPS in the regulation of arousal. Of the three pontine NPS cell clusters, the NPS transcript levels were increased only in the peri-coerulear group in sleep-deprived animals, but not in stress controls. The density of NPS-IR fibers was significantly decreased in the median preoptic nucleus-VLPO region after the sleep deprivation, while radioimmunoassay and mass spectrometry measurements showed a parallel increase of NPS in the anterior hypothalamus. The expression of the NPS receptor was, however, not altered in the VLPO-region. The present results suggest a selective activation of one of the three NPS-expressing neuron clusters as well as release of NPS in distinct forebrain regions after sleep deprivation. Taken together, our results emphasize a role of the peri-coerulear cluster in the modulation of arousal, and the importance of preoptic area for the action of NPS on arousal and sleep.
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| 4. |
- Adori, Csaba, et al.
(författare)
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Neuropeptide S- and Neuropeptide S receptor-expressing neuron populations in the human pons
- 2015
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Ingår i: Frontiers in Neuroanatomy. - : Frontiers Media SA. - 1662-5129. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Neuropeptide S (NPS) is a regulatory peptide with potent pharmacological effects. In rodents, NPS is expressed in a few pontine cell clusters. Its receptor (NPSR1) is, however, widely distributed in the brain. The anxiolytic and arousal promoting effects of NPS make the NPS NPSR1 system an interesting potential drug target in mood-related disorders. However, so far possible disease-related mechanisms involving NPS have only been studied in rodents. To validate the relevance of these animal studies for i.a. drug development, we have explored the distribution of NPS-expressing neurons in the human pons using in situ hybridization and stereological methods and we compared the distribution of NPS mRNA expressing neurons in the human and rat brain. The calculation revealed a total number of 22,317 +/- 2411 NPS mRNA-positive neurons in human, bilaterally. The majority of cells (84%) were located in the parabrachial area in human: in the extension of the medial and lateral parabrachial nuclei, in the Kolliker-Fuse nucleus and around the adjacent lateral lemniscus. In human, in sharp contrast to the rodents, only very few NPS-positive cells (5%) were found close to the locus coeruleus. In addition, we identified a smaller cell cluster (11% of all NPS cells) in the pontine central gray matter both in human and rat, which has not been described previously even in rodents. We also examined the distribution of NPSR1 mRNA-expressing neurons in the human pons. These cells were mainly located in the rostral laterodorsal tegmental nucleus, the cuneiform nucleus, the microcellular tegmental nucleus region and in the periaqueductal gray. Our results show that both NPS and NPSR1 in the human pons are preferentially localized in regions of importance for integration of visceral autonomic information and emotional behavior. The reported interspecies differences must, however, be considered when looking for targets for new pharmacotherapeutical interventions.
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| 5. |
- Barde, Swapnali, et al.
(författare)
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Alterations in the neuropeptide galanin system in major depressive disorder involve levels of transcripts, methylation, and peptide
- 2016
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Ingår i: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA. - : NATL ACAD SCIENCES. - 0027-8424 .- 1091-6490. ; 113:52, s. E8472-E8481
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Tidskriftsartikel (refereegranskat)abstract
- Major depressive disorder (MDD) is a substantial burden to patients, families, and society, but many patients cannot be treated adequately. Rodent experiments suggest that the neuropeptide galanin (GAL) and its three G protein-coupled receptors, GAL(1-3), are involved in mood regulation. To explore the translational potential of these results, we assessed the transcript levels (by quantitative PCR), DNA methylation status (by bisulfite pyrosequencing), and GAL peptide by RIA of the GAL system in postmortem brains from depressed persons who had committed suicide and controls. Transcripts for all four members were detected and showed marked regional variations, GAL and galanin receptor 1 (GALR1) being most abundant. Striking increases in GAL and GALR3 mRNA levels, especially in the noradrenergic locus coeruleus and the dorsal raphe nucleus, in parallel with decreased DNA methylation, were found in both male and female suicide subjects as compared with controls. In contrast, GAL and GALR3 transcript levels were decreased, GALR1 was increased, and DNA methylation was increased in the dorsolateral prefrontal cortex of male suicide subjects, however, there were no changes in the anterior cingulate cortex. Thus, GAL and its receptor GALR3 are differentially methylated and expressed in brains of MDD subjects in a region- and sex-specific manner. Such an epigenetic modification in GALR3, a hyperpolarizing receptor, might contribute to the dysregulation of noradrenergic and serotonergic neurons implicated in the pathogenesis of MDD. Thus, one may speculate that a GAL(3) antagonist could have antidepressant properties by disinhibiting the firing of these neurons, resulting in increased release of noradrenaline and serotonin in forebrain areas involved in mood regulation.
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| 6. |
- Barde, Swapnali
(författare)
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Neuropeptides in the human postmortem brain : focus on galanin and its receptors in depression
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Neuropeptides represent the most diverse family of messenger molecules in the nervous system, which are co-expressed with key neurotransmitters in several brain regions. They modulate synaptic neurotransmission and have, in some cases, also trophic functions. One such neuropeptide, and the focus of the thesis, is ‘galanin’. It is a classical neuropeptide that functions in multiple (patho-) physiological processes, and exerts its actions via three receptors (GalR1-3). A main aim of the thesis is to establish the distribution of, mainly, the galanin system in the human, postmortem brain, but neuropeptide S (NPS) has also been analyzed. We further explore expression of the galanin family genes in postmortem brains from patients suffering from major depressive disorder (MDD). In Paper I we studied the localization of galanin and its three receptor transcripts primarily in the locus coeruleus (LC) and dorsal raphe nucleus (DRN) of ‘normal’, human postmortem brains using RNA in situ hybridization (ISH) and quantitative PCR (qPCR). In the rat brain galanin is known to co-exist with noradrenaline (NA) in most locus LC neurons and with 5- hydroxytryptamine (5-HT) in many DRN neurons, two regions that are considered to be important in mood related disorders. In the human brain, galanin and GalR3 mRNA were found in many NA-LC neurons, and GalR3 mRNA overlapped with tryptophan hydroxylase 2 (TPH2) transcript in at least in some regions of the DRN. However, galanin may not be expressed in 5-HT neurons. qPCR analysis confirmed the expression levels and pattern above, suggesting that distinct species differences exist with regard to galanin and galanin receptor expression in the human brain, when compared to the rat. Such differences are important when defining targets for drug development. The main aim of Paper II was to study galanin and its three receptors in MDD, in our case depressed suicides (Suicides), and controls in five different regions of postmortem brains. We used qPCR to analyze possible changes in expression of transcripts, and pyrosequencing to study DNA methylation. In addition we monitored galanin peptide with radioimmunoassay (RIA). Transcripts for all four members were detected and showed marked regional variations, galanin and GalR1 mRNAs being most abundant. Comparing depressed Suicide subjects and controls, striking results were obtained for galanin and GalR3 transcripts, showing increased mRNA levels, especially in the LC and the DRN of both male and female Suicide subjects, in parallel with decreased DNA methylation. In contrast, galanin and GalR3 transcript levels were decreased in the dorsolateral prefrontal cortex of male Suicide subjects, together with increased DNA methylation, whereas there were no changes in the anterior cingulate cortex. Thus, galanin and its receptor are differentially methylated and expressed in brains of MDD subjects in a region- and sex-specific matter. Already previous animal behavioral experiments and human genetic studies suggest that the galanin system is involved in the pathophysiology of mood disorders. The present results further support this view by revealing a novel link between, on one hand, transcriptomic and epigenetic alterations in the galanin system and, on the other hand, suicidal behavior. In Paper III, we examined the distribution patterns of the transcript for another neuropeptide, NPS, and its receptor, in the human brain and compared the results with the localization in the rat brain. Our findings reveal one clear species difference in that the distinct NPS-positive cell cluster seen adjacent to the LC in rat is virtually missing in the human brain. In summary, these results underline putative, important roles of neuropeptides, especially galanin, in normal and pathophysiological conditions. In particular, there are species differences in expression of galanin receptors between human and rodent noradrenergic and serotonergic neurons. Thus, in humans GalR3, surprisingly, seems to be an important receptor in some key brain stem regions and nuclei, like DRN and LC, whereas in rat, instead, GalR1 and GalR2 are abundant receptors. In fact, GalR3 had previously received only modest attention in studies of the rodent brain. These data link changes in mRNA levels and epigenetic alterations in the galanin system to suicidal behavior, making galanin receptors a novel target for development of antidepressant therapeutics.
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| 7. |
- Barde, Swapnali, et al.
(författare)
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Substance P, NPY, CCK and their receptors in five brain regions in major depressive disorder with transcriptomic analysis of locus coeruleus neurons
- 2024
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Ingår i: European Neuropsychopharmacology. - : Elsevier BV. - 0924-977X .- 1873-7862. ; 78, s. 54-63
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Tidskriftsartikel (refereegranskat)abstract
- Major depressive disorder (MDD) is a serious disease and a burden to patients, families and society. Rodent experiments and human studies suggest that several neuropeptide systems are involved in mood regulation. The aim of this study is two-fold: (i) to monitor, with qPCR, transcript levels of the substance P/tachykinin (TAC), NPY and CCK systems in bulk samples from control and suicide subjects, targeting five postmortem brain regions including locus coeruleus (LC); and (ii) to analyse expression of neuropeptide family transcripts in LC neurons of 'normal' postmortem brains by using laser capture microdissection with Smart-Seq2 RNA sequencing. qPCR revealed distinct regional expression patterns in male and female controls with higher levels for the TAC system in the dorsal raphe nucleus and LC, versus higher transcripts levels of the NPY and CCK systems in prefrontal cortex. In suicide patients, TAC, TAC receptors and a few NPY family transcript levels were increased mainly in prefrontal cortex and LC. The second study on 'normal' noradrenergic LC neurons revealed expression of transcripts for GAL, NPY, TAC1, CCK, and TACR1 and many other peptides (e.g. Cerebellin4 and CARTPT) and receptors (e.g. Adcyap1R1 and GPR173). These data and our previous results on suicide brains indicates that the tachykinin and galanin systems may be valid targets for developing antidepressant medicines. Moreover, the perturbation of neuropeptide systems in MDD patients, and the detection of further neuropeptide and receptor transcripts in LC, shed new light on signalling in noradrenergic LC neurons and on mechanisms possibly associated with mood disorders.
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| 8. |
- Hokfelt, Tomas, et al.
(författare)
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Four decades of research on Viktor Mutt's neuropeptides with focus on galanin
- 2024
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Ingår i: Proceedings of the Estonian Academy of Sciences. - : ESTONIAN ACAD PUBLISHERS. - 1736-6046 .- 1736-7530. ; 73:3, s. 170-192
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the article is to describe our work on peptides discovered in Dr. Mutt's laboratory, particularly galanin. Some personal recollections of meetings with Viktor Mutt and a brief overview of early neuropeptide research at Karolinska Institutet are provided. General aspects on neuropeptide signalling and neuropeptide-neurotransmitter coexistence are followed by the presentation of a possible involvement of the galanin system in pain and depression. Special emphasis is on the role of galanin in the rat and human locus coeruleus. Additional analyses of the human postmortem brains have given results on galanin and other peptides both in the normal prefrontal cortex as well as in different brain regions of depressed patients who have committed suicide and in control subjects. Possible options for developing treatment strategies for pain and depression based on galaninergic mechanisms are discussed. Finally, some recent drugs approved by the FDA for the treatment of conditions such as migraine, which target the signalling of other peptides, are highlighted. In conclusion, the aim of the article is to highlight the potential of the large group of neuropeptides as targets for the development of drugs that may further help patients with illnesses afflicting the nervous system.
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| 9. |
- Hokfelt, Tomas, et al.
(författare)
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Neuropeptide and Small Transmitter Coexistence: Fundamental Studies and Relevance to Mental Illness
- 2018
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Ingår i: Frontiers in Neural Circuits. - : FRONTIERS MEDIA SA. - 1662-5110. ; 12
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Forskningsöversikt (refereegranskat)abstract
- Neuropeptides are auxiliary messenger molecules that always co-exist in nerve cells with one or more small molecule (classic) neurotransmitters. Neuropeptides act both as transmitters and trophic factors, and play a role particularly when the nervous system is challenged, as by injury, pain or stress. Here neuropeptides and coexistence in mammals are reviewed, but with special focus on the 29/30 amino acid galanin and its three receptors GalR1, -R2 and -R3. In particular, galanins role as a co-transmitter in both rodent and human noradrenergic locus coeruleus (LC) neurons is addressed. Extensive experimental animal data strongly suggest a role for the galanin system in depression-like behavior. The translational potential of these results was tested by studying the galanin system in postmortem human brains, first in normal brains, and then in a comparison of five regions of brains obtained from depressed people who committed suicide, and from matched controls. The distribution of galanin and the four galanin system transcripts in the normal human brain was determined, and selective and parallel changes in levels of transcripts and DNA methylation for galanin and its three receptors were assessed in depressed patients who committed suicide: upregulation of transcripts, e.g., for galanin and GalR3 in LC, paralleled by a decrease in DNA methylation, suggesting involvement of epigenetic mechanisms. It is hypothesized that, when exposed to severe stress, the noradrenergic LC neurons fire in bursts and release galanin from their soma/dendrites. Galanin then acts on somato-dendritic, inhibitory galanin autoreceptors, opening potassium channels and inhibiting firing. The purpose of these autoreceptors is to act as a brake to prevent overexcitation, a brake that is also part of resilience to stress that protects against depression. Depression then arises when the inhibition is too strong and long lasting - a maladaption, allostatic load, leading to depletion of NA levels in the forebrain. It is suggested that disinhibition by a galanin antagonist may have antidepressant activity by restoring forebrain NA levels. A role of galanin in depression is also supported by a recent candidate gene study, showing that variants in genes for galanin and its three receptors confer increased risk of depression and anxiety in people who experienced childhood adversity or recent negative life events. In summary, galanin, a neuropeptide coexisting in LC neurons, may participate in the mechanism underlying resilience against a serious and common disorder, MDD. Existing and further results may lead to an increased understanding of how this illness develops, which in turn could provide a basis for its treatment.
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| 10. |
- Kawa, Lizan, et al.
(författare)
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Expression of galanin and its receptors are perturbed in a rodent model of mild, blast-induced traumatic brain injury
- 2016
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Ingår i: Experimental Neurology. - : ACADEMIC PRESS INC ELSEVIER SCIENCE. - 0014-4886 .- 1090-2430. ; 279, s. 159-167
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Tidskriftsartikel (refereegranskat)abstract
- The symptomatology, mood and cognitive disturbances seen in post-traumatic stress disorder (PTSD) and mild blast-induced traumatic brain injury (mbTBI) overlap considerably. However the pathological mechanisms underlying the two conditions are currently unknown. The neuropeptide galanin has been suggested to play a role in the development of stress and mood disorders. Here we applied bio- and histochemical methods with the aim to elucidate the nature of any changes in the expression of galanin and its receptors in a rodent model of mbTBI. In situ hybridization and quantitative polymerase chain reaction studies revealed significant, injury induced changes, in some cases lasting at least for one week, in the mRNA levels of galanin and/or its three receptors, galanin receptor 1-3 (GalR1-3). Such changes were seen in several forebrain regions, and the locus coeruleus. In the ventral periaqueductal gray GalR1 mRNA levels were increased, while GalR2 were decreased. Analysis of galanin peptide levels using radioimmunoassay demonstrated an increase in several brain regions including the locus coeruleus, dorsal hippocampal formation and amygdala. These findings suggest a role for the galanin system in the endogenous response to mbTBI, and that pharmacological studies of the effects of activation or inhibition of different galanin receptors in combination with functional assays of behavioral recovery may reveal promising targets for new therapeutic strategies in mbTBI. (C) 2016 Elsevier Inc. All rights reserved.
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