Philosophical transactions of the Royal Society of London. Series B, Biological sciences
Frehner, SS;Dooley, KT;Palumbo, MC;Smith, AL;Goodman, MM;Bales, KL;Freeman, SM;
PMID: 35858098 | DOI: 10.1098/rstb.2021.0118
Oxytocin is an endogenous neuropeptide hormone that influences social behaviour and bonding in mammals. Variations in oxytocin receptor (OXTR) expression may play a role in the social deficits seen in autism spectrum disorder. Previous studies from our laboratory found a dense population of OXTR in the human substantia nigra (SN), a basal ganglia structure in the midbrain that is important in both movement and reward pathways. Here, we explore whether differences in OXTR can be identified in the dopaminergic SN pars compacta of individuals with autism. Postmortem human brain tissue specimens were processed for OXTR autoradiography from four groups: males with autism, females with autism, typically developing (TD) males and TD females. We found that females with autism had significantly lower levels of OXTR than the other groups. To examine potential gene expression differences, we performed in situ hybridization in adjacent slides to visualize and quantify OXTR mRNA as well as mRNA for tyrosine hydroxylase. We found no differences in mRNA levels for either gene across the four groups. These results suggest that a dysregulation in local OXTR protein translation or increased OXTR internalization/recycling may contribute to the differences in social symptoms seen in females with autism. This article is part of the theme issue 'Interplays between oxytocin and other neuromodulators in shaping complex social behaviours'.
Skiteva, O;Yao, N;Mantas, I;Zhang, X;Perlmann, T;Svenningsson, P;Chergui, K;
PMID: 37029193 | DOI: 10.1038/s41531-023-00500-5
In Parkinson's disease (PD), axons of dopaminergic (DA) neurons in the substantia nigra pars compacta (SNc) degenerate before their cell bodies. Calcium influx during pacemaker firing might contribute to neuronal loss, but it is not known if dysfunctions of voltage-gated calcium channels (VGCCs) occur in DA neurons somata and axon terminals. We investigated T-type and L-type VGCCs in SNc-DA neurons of two mouse models of PD: mice with a deletion of the Nurr1 gene in DA neurons from an adult age (cNurr1 mice), and mice bearing the G2019S mutation in the gene coding for LRRK2 (G2019S mice). Adult cNurr1 mice displayed motor and DA deficits, while middle-aged G2019S mice did not. The number and morphology of SNc-DA neurons, most of their intrinsic membrane properties and pacemaker firing were unaltered in cNurr1 and G2019S mice compared to their control and wild-type littermates. L-type VGCCs contributed to the pacemaker firing of SNc-DA neurons in G2019S mice, but not in control, wild-type, and cNurr1 mice. In cNurr1 mice, but not G2019S mice, the contribution of T-type VGCCs to the pacemaker firing of SNc-DA neurons was reduced, and somatic dopamine-D2 autoreceptors desensitized more. Altered contribution of L-type and T-type VGCCs to the pacemaker firing was not observed in the presence of a LRRK2 kinase inhibitor in G2019S mice, and in the presence of a flavonoid with antioxidant activity in G2019S and cNurr1 mice. The role of L-type and T-type VGCCs in controlling dopamine release from axon terminals in the striatum was unaltered in cNurr1 and G2019S mice. Our findings uncover opposite changes, linked to oxidative stress, in the function of two VGCCs in DA neurons somata, but not axon terminals, in two different experimental PD models.
Cline, MM;Juarez, B;Hunker, A;Regiarto, EG;Hariadi, B;Soden, ME;Zweifel, LS;
PMID: 36927614 | DOI: 10.7554/eLife.83760
The axonal guidance cue netrin-1 serves a critical role in neural circuit development by promoting growth cone motility, axonal branching, and synaptogenesis. Within the adult mouse brain, expression of the gene encoding (Ntn1) is highly enriched in the ventral midbrain where it is expressed in both GABAergic and dopaminergic neurons, but its function in these cell types in the adult system remains largely unknown. To address this, we performed viral-mediated, cell-type specific CRISPR-Cas9 mutagenesis of Ntn1 in the ventral tegmental area (VTA) of adult mice. Ntn1 loss-of-function in either cell type resulted in a significant reduction in excitatory postsynaptic connectivity. In dopamine neurons, the reduced excitatory tone had a minimal phenotypic behavioral outcome; however, reduced glutamatergic tone on VTA GABA neurons induced behaviors associated with a hyperdopaminergic phenotype. Simultaneous loss of Ntn1 function in both cell types largely rescued the phenotype observed in the GABA-only mutagenesis. These findings demonstrate an important role for Ntn1 in maintaining excitatory connectivity in the adult midbrain and that a balance in this connectivity within two of the major cell types of the VTA is critical for the proper functioning of the mesolimbic system.
Uchiyama, S;Yoshihara, K;Kawanabe, R;Hatada, I;Koga, K;Tsuda, M;
PMID: 34980215 | DOI: 10.1186/s13041-021-00895-3
It is well known that acute exposure to physical stress produces a transient antinociceptive effect (called stress-induced analgesia [SIA]). One proposed mechanism for SIA involves noradrenaline (NA) in the central nervous system. NA has been reported to activate inhibitory neurons in the spinal dorsal horn (SDH), but its in vivo role in SIA remains unknown. In this study, we found that an antinociceptive effect on noxious heat after acute exposure to restraint stress was impaired in mice with a conditional knockout of α1A-adrenaline receptors (α1A-ARs) in inhibitory neurons (Vgat-Cre;Adra1aflox/flox mice). A similar reduction was also observed in mice treated with N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine, a selective neurotoxin for NAergic neurons in the locus coeruleus (LC). Furthermore, whole-cell patch-clamp recordings using spinal cord slices revealed that NA-induced increase in the frequency of spontaneous inhibitory postsynaptic currents in the substantia gelatinosa neurons was suppressed by silodosin, an α1A-AR antagonist, and by conditional knockout of α1A-ARs in inhibitory neurons. Moreover, under unstressed conditions, the antinociceptive effects of intrathecal NA and phenylephrine on noxious heat were lost in Vgat-Cre;Adra1aflox/flox mice. Our findings suggest that activation of α1A-ARs in SDH inhibitory neurons, presumably via LC-NAergic neurons, is necessary for SIA to noxious heat.
Science translational medicine
Huang, WC;Peng, Z;Murdock, MH;Liu, L;Mathys, H;Davila-Velderrain, J;Jiang, X;Chen, M;Ng, AP;Kim, T;Abdurrob, F;Gao, F;Bennett, DA;Kellis, M;Tsai, LH;
PMID: 37075128 | DOI: 10.1126/scitranslmed.abq1019
The neural circuits governing the induction and progression of neurodegeneration and memory impairment in Alzheimer's disease (AD) are incompletely understood. The mammillary body (MB), a subcortical node of the medial limbic circuit, is one of the first brain regions to exhibit amyloid deposition in the 5xFAD mouse model of AD. Amyloid burden in the MB correlates with pathological diagnosis of AD in human postmortem brain tissue. Whether and how MB neuronal circuitry contributes to neurodegeneration and memory deficits in AD are unknown. Using 5xFAD mice and postmortem MB samples from individuals with varying degrees of AD pathology, we identified two neuronal cell types in the MB harboring distinct electrophysiological properties and long-range projections: lateral neurons and medial neurons. lateral MB neurons harbored aberrant hyperactivity and exhibited early neurodegeneration in 5xFAD mice compared with lateral MB neurons in wild-type littermates. Inducing hyperactivity in lateral MB neurons in wild-type mice impaired performance on memory tasks, whereas attenuating aberrant hyperactivity in lateral MB neurons ameliorated memory deficits in 5xFAD mice. Our findings suggest that neurodegeneration may be a result of genetically distinct, projection-specific cellular dysfunction and that dysregulated lateral MB neurons may be causally linked to memory deficits in AD.
Godefroy, D;Boukhzar, L;Mallouki, BY;Carpentier, E;Dubessy, C;Chigr, F;Tillet, Y;Anouar, Y;
PMID: 35066506 | DOI: 10.1159/000522091
Selenoprotein T (SELENOT), a PACAP-regulated thioredoxin-like protein, plays a role in catecholamine secretion and protects dopaminergic neurons. However, the role of SELENOT in the establishment of the catecholaminergic (CA) neuronal system is not known yet.We analyzed by immunohistochemistry and RNAscope in situ hybridization the distribution of SELENOT and the expression of its mRNA, respectively. In addition, 3D imaging involving immunostaining in toto, clearing through the iDISCO+ method, acquisitions by light sheet microscopy and processing of 3D images was performed to map the CA neuronal system. A semi-automatic quantification of 3D images was carried out.SELENOT protein and mRNA are widely distributed in the mouse brain, with important local variations. Three-dimensional mapping, through tyrosine hydroxylase (TH) labeling, and semi-automated quantification of CA neurons in brain-specific SELENOT knockout mice showed a significant decrease in the number of TH-positive neurons in the area postrema (AP-A2), the A11 cell group (A11) and the zona incerta (ZI-A13) of SELENOT-deficient females, and in the hypothalamus (Hyp-A12-A14-A15) of SELENOT-deficient females and males.These results showed that SELENOT is diffusely expressed in the mouse brain and that its deficiency impacts CA neuron distribution in different brain areas including Hyp-A12-A14-A15, in both male and female mice.S. Karger AG, Basel.
Han X, He Y, Bi GH, Zhang HY, Song R, Liu QR, Egan JM, Gardner EL, Li J, Xi ZX.
PMID: 28951549 | DOI: 10.1038/s41598-017-12399-z
Cannabis can be rewarding or aversive. Cannabis reward is believed to be mediated by activation of cannabinoid CB1 receptors (CB1Rs) on GABAergic neurons that disinhibit dopaminergic neurons in the ventral tegmental area (VTA). However, little is known about the mechanisms underlying cannabis aversion in rodents. In the present study, CB1Rs are found not only on VTA GABAergic neurons, but also on VTA glutamatergic neurons that express vesicular glutamate transporter 2 (VgluT2). We then used Cre-Loxp transgenic technology to selectively delete CB1Rs in VgluT2-expressing glutamatergic neurons (VgluT2-CB1 -/-) and Cre-dependent viral vector to express light-sensitive channelrhodopsin-2 into VTA glutamatergic neurons. We found that photoactivation of VTA glutamatergic neurons produced robust intracranial self-stimulation (ICSS) behavior, which was dose-dependently blocked by DA receptor antagonists, but enhanced by cocaine. In contrast, Δ9-tetrahydrocannabinol (Δ9-THC), the major psychoactive component of cannabis, produced dose-dependent conditioned place aversion and a reduction in the above optical ICSS in VgluT2-cre control mice, but not in VgluT2-CB1 -/- mice. These findings suggest that activation of CB1Rs in VgluT2-expressing glutamate neurons produces aversive effects that might explain why cannabinoid is not rewarding in rodents and might also account for individual differences in the hedonic effects of cannabis in humans.
Cannabinoid CB2 receptors are expressed in glutamate neurons in the red nucleus and functionally modulate motor behavior in mice
Zhang, HY;Shen, H;Gao, M;Ma, Z;Hempel, B;Bi, GH;Gardner, EL;Wu, J;Xi, ZX;
PMID: 33789118 | DOI: 10.1016/j.neuropharm.2021.108538
Cannabinoids produce a number of central nervous system effects via the CB2 receptor (CB2R), including analgesia, antianxiety, anti-reward, hypoactivity and attenuation of opioid-induced respiratory depression. However, the cellular distributions of the CB2Rs in the brain remain unclear. We have reported that CB2Rs are expressed in midbrain dopamine (DA) neurons and functionally regulate DA-mediated behavior(s). Unexpectedly, high densities of CB2-like signaling were also found in a neighboring motor structure - the red nucleus (RN) of the midbrain. In the present study, we systematically explored CB2R expression and function in the RN. Immunohistochemistry and in situ hybridization assays showed high densities of CB2R-immunostaining and mRNA signal in RN magnocellular glutamate neurons in wildtype and CB1-knockout, but not CB2-knockout, mice. Ex vivo electrophysiological recordings in midbrain slices demonstrated that CB2R activation by JWH133 dose-dependently inhibited firing rates of RN magnocellular neurons in wildtype, but not CB2-knockout, mice, while having no effect on RN GABA neurons in transgenic GAD67-GFP reporter mice, suggesting CB2-mediated effects on glutamatergic neurons. In addition, microinjection of JWH133 into the RN produced robust ipsilateral rotations in wildtype, but not CB2-knockout mice, which was blocked by pretreatment with either a CB2 or DA D1 or D2 receptor antagonist, suggesting a DA-dependent effect. Finally, fluorescent tract tracing revealed glutamatergic projections from the RN to multiple brain areas including the ventral tegmental area, nucleus accumbens, thalamus, and cerebellum. These findings suggest that CB2Rs in RN glutamate neurons functionally modulate motor activity, and therefore, constitute a new target in cannabis-based medication development for motor disorders.
Biomedicine & pharmacotherapy = Biomedecine & pharmacotherapie
Ding, X;Yang, M;Wu, N;Li, J;Song, R;
PMID: 36592493 | DOI: 10.1016/j.biopha.2022.114179
The abnormal fear memory will lead to the onset of stress disorders, such as post-traumatic stress disorder (PTSD) and so on. Therefore, the intervention in the formation of abnormal fear memory will provide a new strategy for the prevention and treatment of PTSD. In our previous studies, we found that blockade of dopamine D3 receptor (DRD3) with highly selective antagonist YQA14 or knockout of DRD3 was able to attenuate the expression or retrieval of fear memory in PTSD animal models. However, the neurobiological mechanism of regulation of DRD3 in fear is unclear. In the present research, we clarified that DRD3 was expressed in the dopaminergic (DAergic) neurons in the ventral tegmental area (VTA). Then, we identified that microinjection of YQA14 (1 μg/0.2 μl/side) in VTA before the aversive stimuli in the training session or during days subsequent to the shock significantly meliorated the freezing behaviors in the inescapable electric foot-shock model. At last, using fiber photometry system, we found that microinjection of YQA14 in VTA promoted the dopamine neurotransmitter release in the basolateral amygdala (BLA), and pre-training YQA14 infusion in VTA lowered the increase of dopamine (DA) in BLA induced by shock during the training session or by context during the retrieval session. All above the results demonstrated that YQA14 attenuated the fear learning through the blockade of DRD3 in VTA decreasing the excitability of the projection to BLA. This study may provide new mechanisms and potential intervention targets for stress disorders with abnormal fear memory.
Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology
McNulty, CJ;Fallon, IP;Amat, J;Sanchez, RJ;Leslie, NR;Root, DH;Maier, SF;Baratta, MV;
PMID: 36076018 | DOI: 10.1038/s41386-022-01443-w
Stress-linked disorders are more prevalent in women than in men and differ in their clinical presentation. Thus, investigating sex differences in factors that promote susceptibility or resilience to stress outcomes, and the circuit elements that mediate their effects, is important. In male rats, instrumental control over stressors engages a corticostriatal system involving the prelimbic cortex (PL) and dorsomedial striatum (DMS) that prevent many of the sequelae of stress exposure. Interestingly, control does not buffer against stress outcomes in females, and here, we provide evidence that the instrumental controlling response in females is supported instead by the dorsolateral striatum (DLS). Additionally, we used in vivo microdialysis, fluorescent in situ hybridization, and receptor subtype pharmacology to examine the contribution of prefrontal dopamine (DA) to the differential impact of behavioral control. Although both sexes preferentially expressed D1 receptor mRNA in PL GABAergic neurons, there were robust sex differences in the dynamic properties of prefrontal DA during controllable stress. Behavioral control potently attenuated stress-induced DA efflux in males, but not females, who showed a sustained DA increase throughout the entire stress session. Importantly, PL D1 receptor blockade (SCH 23390) shifted the proportion of striatal activity from the DLS to the DMS in females and produced the protective effects of behavioral control. These findings suggest a sex-selective mechanism in which elevated DA in the PL biases instrumental responding towards prefrontal-independent striatal circuitry, thereby eliminating the protective impact of coping with stress.
Zalachoras, I;Astori, S;Meijer, M;Grosse, J;Zanoletti, O;de Suduiraut, IG;Deussing, JM;Sandi, C;
PMID: 35319997 | DOI: 10.1126/sciadv.abj9019
Individuals frequently differ in their behavioral and cognitive responses to stress. However, whether motivation is differently affected by acute stress in different individuals remains to be established. By exploiting natural variation in trait anxiety in outbred Wistar rats, we show that acute stress facilitates effort-related motivation in low anxious animals, while dampening effort in high anxious ones. This model allowed us to address the mechanisms underlying acute stress-induced differences in motivated behavior. We show that CRHR1 expression levels in dopamine neurons of the ventral tegmental area (VTA)-a neuronal type implicated in the regulation of motivation-depend on animals' anxiety, and these differences in CRHR1 expression levels explain the divergent effects of stress on both effortful behavior and the functioning of mesolimbic DA neurons. These findings highlight CRHR1 in VTA DA neurons-whose levels vary with individuals' anxiety-as a switching mechanism determining whether acute stress facilitates or dampens motivation.
Involvement of Scratch2 in GalR1-mediated depression-like behaviors in the rat ventral periaqueductal gray
Proceedings of the National Academy of Sciences of the United States of America
Yang, Y;Li, Y;Liu, B;Li, C;Liu, Z;Deng, J;Luo, H;Li, X;Wu, J;Li, H;Wang, CY;Zhao, M;Wu, H;Lallemend, F;Svenningsson, P;Hökfelt, TGM;Xu, ZD;
PMID: 34108238 | DOI: 10.1073/pnas.1922586118
Galanin receptor1 (GalR1) transcript levels are elevated in the rat ventral periaqueductal gray (vPAG) after chronic mild stress (CMS) and are related to depression-like behavior. To explore the mechanisms underlying the elevated GalR1 expression, we carried out molecular biological experiments in vitro and in animal behavioral experiments in vivo. It was found that a restricted upstream region of the GalR1 gene, from -250 to -220, harbors an E-box and plays a negative role in the GalR1 promoter activity. The transcription factor Scratch2 bound to the E-box to down-regulate GalR1 promoter activity and lower expression levels of the GalR1 gene. The expression of Scratch2 was significantly decreased in the vPAG of CMS rats. Importantly, local knockdown of Scratch2 in the vPAG caused elevated expression of GalR1 in the same region, as well as depression-like behaviors. RNAscope analysis revealed that GalR1 mRNA is expressed together with Scratch2 in both GABA and glutamate neurons. Taking these data together, our study further supports the involvement of GalR1 in mood control and suggests a role for Scratch2 as a regulator of depression-like behavior by repressing the GalR1 gene in the vPAG.
