| 1. |
- Sikora, Magdalena, et al.
(författare)
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NMDA Receptors on Dopaminoceptive Neurons Are Essential for Drug-Induced Conditioned Place Preference.
- 2016
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Ingår i: eNeuro. - 2373-2822. ; 3:3
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Tidskriftsartikel (refereegranskat)abstract
- Plasticity of the brain's dopamine system plays a crucial role in adaptive behavior by regulating appetitive motivation and the control of reinforcement learning. In this study, we investigated drug- and natural-reward conditioned behaviors in a mouse model in which the NMDA receptor-dependent plasticity of dopaminoceptive neurons was disrupted. We generated a transgenic mouse line with inducible selective inactivation of the NR1 subunit in neurons expressing dopamine D1 receptors (the NR1(D1CreERT2) mice). Whole-cell recordings of spontaneous EPSCs on neurons in the nucleus accumbens confirmed that a population of neurons lacked the NMDA receptor-dependent component of the current. This effect was accompanied by impaired long-term potentiation in the nucleus accumbens and in the CA1 area of the ventral, but not the dorsal, hippocampus. Mutant mice did not differ from control animals when tested for pavlovian or instrumental conditioning. However, NR1(D1CreERT2) mice acquired no preference for a context associated with administration of drugs of abuse. In the conditioned place preference paradigm, mutant mice did not spend more time in the context paired with cocaine, morphine, or ethanol, although these mice acquired a preference for sucrose jelly and an aversion to naloxone injections, as normal. Thus, we observed that the selective inducible ablation of the NMDA receptors specifically blocks drug-associated context memory with no effect on positive reinforcement in general.
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| 2. |
- Engström-Ruud, Linda, et al.
(författare)
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Activation of GFRAL+ neurons induces hypothermia and glucoregulatory responses associated with nausea and torpor.
- 2024
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Ingår i: Cell reports. - 2211-1247. ; 43:4
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Tidskriftsartikel (refereegranskat)abstract
- GFRAL-expressing neurons actuate aversion and nausea, are targets for obesity treatment, and may mediate metformin effects by long-term GDF15-GFRAL agonism. Whether GFRAL+ neurons acutely regulate glucose and energy homeostasis is, however, underexplored. Here, we report that cell-specific activation of GFRAL+ neurons using a variety of techniques causes a torpor-like state, including hypothermia, the release of stress hormones, a shift from glucose to lipid oxidation, and impaired insulin sensitivity, glucose tolerance, and skeletal muscle glucose uptake but augmented glucose uptake in visceral fat. Metabolomic analysis of blood and transcriptomics of muscle and fat indicate alterations in ketogenesis, insulin signaling, adipose tissue differentiation and mitogenesis, and energy fluxes. Our findings indicate that acute GFRAL+ neuron activation induces endocrine and gluco- and thermoregulatory responses associated with nausea and torpor. While chronic activation of GFRAL signaling promotes weight loss in obesity, these results show that acute activation of GFRAL+ neurons causes hypothermia and hyperglycemia.
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| 3. |
- Eskilsson, Anna, et al.
(författare)
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Immune-Induced Fever Is Dependent on Local But Not Generalized Prostaglandin E-2 Synthesis in the Brain
- 2017
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Ingår i: Journal of Neuroscience. - : SOC NEUROSCIENCE. - 0270-6474 .- 1529-2401. ; 37:19, s. 5035-5044
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Tidskriftsartikel (refereegranskat)abstract
- Fever occurs upon binding of prostaglandin E-2 (PGE(2)) to EP3 receptors in the median preoptic nucleus of the hypothalamus, but the origin of the pyrogenic PGE(2) has not been clearly determined. Here, using mice of both sexes, we examined the role of local versus generalized PGE(2) production in the brain for the febrile response. In wild-type mice and in mice with genetic deletion of the prostaglandin synthesizing enzyme cyclooxygenase-2 in the brain endothelium, generated with an inducible CreER(T2) under the Slco1c1 promoter, PGE(2) levels in the CSF were only weakly related to the magnitude of the febrile response, whereas the PGE(2) synthesizing capacity in the hypothalamus, as reflected in the levels of cyclooxygenase-2 mRNA, showed strong correlation with the immune-induced fever. Histological analysis showed that the deletion of cyclooxygenase-2 in brain endothelial cells occurred preferentially in small-and medium-sized vessels deep in the brain parenchyma, such as in the hypothalamus, whereas larger vessels, and particularly those close to the neocortical surface and in the meninges, were left unaffected, hence leaving PGE(2) synthesis largely intact in major parts of the brain while significantly reducing it in the region critical for the febrile response. Furthermore, injection of a virus vector expressing microsomal prostaglandin E synthase-1 (mPGES-1) into the median preoptic nucleus of fever-refractive mPGES-1 knock-out mice, resulted in a temperature elevation in response to LPS. We conclude that the febrile response is dependent on local release of PGE(2) onto its target neurons and not on the overall PGE(2) production in the brain.
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| 4. |
- Fritz, Michael, et al.
(författare)
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Prostaglandin-dependent modulation of dopaminergic neurotransmission elicits inflammation-induced aversion in mice
- 2016
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Ingår i: Journal of Clinical Investigation. - : AMER SOC CLINICAL INVESTIGATION INC. - 0021-9738 .- 1558-8238. ; 126:2, s. 695-705
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Tidskriftsartikel (refereegranskat)abstract
- Systemic inflammation causes malaise and general feelings of discomfort. This fundamental aspect of the sickness response reduces the quality of life for people suffering from chronic inflammatory diseases and is a nuisance during mild infections like common colds or the flu. To investigate how inflammation is perceived as unpleasant and causes negative affect, we used a behavioral test in which mice avoid an environment that they have learned to associate with inflammation-induced discomfort. Using a combination of cell-type-specific gene deletions, pharmacology, and chemogenetics, we found that systemic inflammation triggered aversion through MyD88-dependent activation of the brain endothelium followed by COX1-mediated cerebral prostaglandin E-2 (PGE(2)) synthesis. Further, we showed that inflammation-induced PGE(2) targeted EP1 receptors on striatal dopamine D1 receptor-expressing neurons and that this signaling sequence induced aversion through GABA-mediated inhibition of dopaminergic cells. Finally, we demonstrated that inflammation-induced aversion was not an indirect consequence of fever or anorexia but that it constituted an independent inflammatory symptom triggered by a unique molecular mechanism. Collectively, these findings demonstrate that PGE(2)-mediated modulation of the dopaminergic motivational circuitry is a key mechanism underlying the negative affect induced by inflammation.
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| 5. |
- Singh, Anand Kumar, et al.
(författare)
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Prostaglandin-mediated inhibition of serotonin signaling controls the affective component of inflammatory pain
- 2017
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Ingår i: Journal of Clinical Investigation. - : AMER SOC CLINICAL INVESTIGATION INC. - 0021-9738 .- 1558-8238. ; 127:4, s. 1370-1374
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Tidskriftsartikel (refereegranskat)abstract
- Pain is fundamentally unpleasant and induces a negative affective state. The affective component of pain is mediated by circuits that are distinct from those mediating the sensory-discriminative component. Here, we have investigated the role of prostaglandins in the affective dimension of pain using a rodent pain assay based on conditioned place aversion to formalin injection, an inflammatory noxious stimulus. We found that place aversion induced by inflammatory pain depends on prostaglandin E-2 that is synthesized by cyclooxygenase 2 in neural cells. Further, mice lacking the prostaglandin E-2 receptor EP3 selectively on serotonergic cells or selectively in the area of the dorsal raphe nucleus failed to form an aversion to formalininduced pain, as did mice lacking the serotonin transporter. Chemogenetic manipulations revealed that EP3 receptor activation elicited conditioned place aversion to pain via inhibition of serotonergic neurons. In contrast to their role in inflammatory pain aversion, EP3 receptors on serotonergic cells were dispensable for acute nociceptive behaviors and for aversion induced by thermal pain or a kappa opioid receptor agonist. Collectively, our findings show that prostaglandin-mediated modulation of serotonergic transmission controls the affective component of inflammatory pain.
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| 6. |
- Stojakovic, Andrea, et al.
(författare)
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Several behavioral traits relevant for alcoholism are controlled by gamma 2 subunit containing GABA(A) receptors on dopamine neurons in mice
- 2018
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Ingår i: Neuropsychopharmacology. - : NATURE PUBLISHING GROUP. - 0893-133X .- 1740-634X. ; 43:7, s. 1548-1556
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Tidskriftsartikel (refereegranskat)abstract
- The risk factors for developing alcohol addiction include impulsivity, high sensitivity to the rewarding action of ethanol, and low sensitivity to its sedative and intoxicating effects. Genetic variation in GABA(A) receptor subunits, including the gamma 2 subunit (Gabrg2), affects the risk for developing alcoholism. Alcohol directly potentiates GABA(A) receptors and activates the mesolimbic dopamine system. Here, we deleted Gabrg2 selectively in dopamine cells of adult mice. The deletion resulted in elevated firing of dopamine neurons and made them less sensitive to drugs acting at GABA(A) receptors. At the behavioral level, the deletion increased exploratory behavior and augmented both correct and incorrect responding in the go/no-go task, a test often used to assay the response inhibition component of impulsivity. In addition, conditioned place preference to alcohol, but not to cocaine or morphine, was increased. Ethanol-induced locomotor activation was enhanced in the mice lacking Gabrg2 on dopaminergic cells, whereas the sedative effect of alcohol was reduced. Finally, the alcohol drinking, but not the alcohol preference, at a high concentration was increased in the mutant mice. In summary, deletion of Gabrg2 on dopamine cells induced several behavioral traits associated with high risk of developing alcoholism. The findings suggest that mice lacking Gabrg2 on dopaminergic cells could be used as models for individuals at high risk for developing alcoholism and that GABA(A) receptors on dopamine cells are protective against the development of excessive alcohol drinking.
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| 7. |
- Wilhelms, Daniel, et al.
(författare)
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CGRP Is Critical for Hot Flushes in Ovariectomized Mice
- 2019
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Ingår i: Frontiers in Pharmacology. - : FRONTIERS MEDIA SA. - 1663-9812. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Hot flushes are common and troublesome symptoms of menopause. The neuropeptide calcitonin gene-related peptide (CGRP) is increased in plasma during hot flushes but it has not been clear if CGRP is causally involved in the mechanism underpinning the flushes. Here, we examined the effect of interventions with CGRP in a mouse model of hot flushes based on flush-like temperature increases triggered by forced physical activity in ovariectomized mice. Compared to normal mice, ovariectomized mice reacted with an exaggerated, flush-like, temperature increase after physical exercise. This increase was completely blocked by the non-peptide CGRP-antagonist MK-8825 (-0.41 degrees Celsius, 95% CI: -0,83 to 0,012, p amp;lt; 0.0001) at a dose that had no obvious effects on locomotor activity (50 mg/kg). Further, the flush-like temperature increases were strongly attenuated in ovariectomized mice lacking alpha CGRP due to a genetic modification. Collectively, our findings suggest that CGRP is an important mediator of experimentally induced hot flushes and they identify CGRP antagonists as promising treatment candidates for women and possibly also men with hot flushes.
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| 8. |
- Wilhelms, Daniel, et al.
(författare)
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Cyclooxygenase Isoform Exchange Blocks Brain-Mediated Inflammatory Symptoms
- 2016
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Ingår i: PLOS ONE. - : PUBLIC LIBRARY SCIENCE. - 1932-6203. ; 11:11
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Tidskriftsartikel (refereegranskat)abstract
- Cyclooxygenase-2 (COX-2) is the main source of inducible prostaglandin E-2 production and mediates inflammatory symptoms including fever, loss of appetite and hyperalgesia. COX-1 is dispensable for fever, anorexia and hyperalgesia but is important for several other functions both under basal conditions and during inflammation. The differential functionality of the COX isoforms could be due to differences in the regulatory regions of the genes, leading to different expression patterns, or to differences in the coding sequence, resulting in distinct functional properties of the proteins. To study the molecular underpinnings of the functional differences between the two isoforms in the context of inflammatory symptoms, we used mice in which the coding sequence of COX-2 was replaced by the corresponding sequence of COX-1. In these mice, COX-1 mRNA was induced by inflammation but COX-1 protein expression did not fully mimic inflammation-induced COX-2 expression. Just like mice globally lacking COX-2, these mice showed a complete lack of fever and inflammation-induced anorexia as well as an impaired response to inflammatory pain. However, as previously reported, they displayed close to normal survival rates, which contrasts to the high fetal mortality in COX-2 knockout mice. This shows that the COX activity generated from the hybrid gene was strong enough to allow survival but not strong enough to mediate the inflammatory symptoms studied, making the line an interesting alternative to COX-2 knockouts for the study of inflammation. Our results also show that the functional differences between COX-1 and COX-2 in the context of inflammatory symptoms are not only dependent on the features of the promoter regions. Instead they indicate that there are fundamental differences between the isoforms at translational or posttranslational levels.
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| 9. |
- Zajdel, Joanna, 1989-, et al.
(författare)
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Acute maternal separation potentiates the gene expression and corticosterone response induced by inflammation
- 2019
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Ingår i: Brain, behavior, and immunity. - : Elsevier. - 0889-1591 .- 1090-2139. ; 77, s. 141-149
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Tidskriftsartikel (refereegranskat)abstract
- Maternal care is crucial for infants and profoundly affects their responses to different kinds of stressors. Here, we examined how maternal separation affects inflammatory gene expression and the corticosterone response to an acute immune challenge induced by lipopolysaccharide (LPS; 40 µg/kg ip) in mouse pups, 8–9 days old. Maternal separation initially attenuated LPS-induced hypothalamic pro-inflammatory gene expression, but later, at 3 h after immune challenge, robustly augmented such gene expression and increased serum corticosterone levels. Providing the pups with a warm and soft object prevented the separation-induced augmented hypothalamic-pituitary-adrenal (HPA)-axis response. It also prevented the potentiated induction of some, but not all, inflammatory genes to a similar extent as did the dam. Our results show that maternal separation potentiates the inflammatory response and the resulting HPA-axis activation, which may have detrimental effects if separation is prolonged or repeated.
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| 10. |
- Zajdel, Joanna, et al.
(författare)
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Calcitonin gene related peptide alpha is dispensable for many danger-related motivational responses
- 2021
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Ingår i: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- Calcitonin gene related peptide (CGRP) expressing neurons in the parabrachial nucleus have been shown to encode danger. Through projections to the amygdala and other forebrain structures, they regulate food intake and trigger adaptive behaviors in response to threats like inflammation, intoxication, tumors and pain. Despite the fact that this danger-encoding neuronal population has been defined based on its CGRP expression, it is not clear if CGRP is critical for its function. It is also not clear if CGRP in other neuronal structures is involved in danger-encoding. To examine the role of CGRP in danger-related motivational responses, we used male and female mice lacking alpha CGRP, which is the main form of CGRP in the brain. These mice had no, or only very weak, CGRP expression. Despite this, they did not behave differently compared to wildtype mice when they were tested for a battery of danger-related responses known to be mediated by CGRP neurons in the parabrachial nucleus. Mice lacking alpha CGRP and wildtype mice showed similar inflammation-induced anorexia, conditioned taste aversion, aversion to thermal pain and pain-induced escape behavior, although it should be pointed out that the study was not powered to detect any possible differences that were minor or sex-specific. Collectively, our findings suggest that alpha CGRP is not necessary for many threat-related responses, including some that are known to be mediated by CGRP neurons in the parabrachial nucleus.
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| 11. |
- Zajdel, Joanna, 1989-
(författare)
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Interactions between the brain and the immune system in pain and inflammation
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Reciprocal interactions between the nervous and immune systems have gained a lot of attention in the last two decades, especially after demonstrating that cytokine immunotherapies can induce depression and after describing the inflammatory reflex. A lot of effort has been dedicated to understanding how the signals from the immune system reach the brain and vice versa, and on their role in health and disease. However, it is not well-known which of the brain circuits, receptors and signalling molecules give rise to behavioural and affective changes induced by inflammation, such as reduced food intake and induction of negative mood. Moreover, although it is well established that early life stress leads to an increased risk of developing inflammatory diseases in adulthood, the acute effects of stress on the inflammatory response in childhood are not well described. Using mouse models of systemic and local inflammation, I studied (1) how inflammatory pain elicits negative affect, (2) if CGRPα is necessary for parabrachial-amygdaloid pathway-mediated behaviours associated with pain and inflammation, and finally, (3) what are the effects of stress on the inflammatory process during early life. The results indicate that (1) the negative affect of inflammatory pain is triggered by inhibition of serotonergic neurons of the dorsal raphe nucleus, as a result of prostaglandin E2 binding to EP3 receptors; (2) CGRPα is dispensable for most pain- and inflammation-related protective behaviours; (3) acute stress potentiates the pro-inflammatory cytokine expression after an inflammatory challenge in mouse pups. The phenomena studied here can contribute to understanding how immune system activation induces changes in mood and behaviour common for inflammation and depression.
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