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'.
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.
Hu, S;Wang, Y;Han, X;Dai, M;Zhang, Y;Ma, Y;Weng, S;Xiao, L;
PMID: 36127701 | DOI: 10.1186/s12915-022-01405-0
Oxytocin, secreted by oxytocin neurons in the hypothalamus, is an endogenous neuropeptide involved in modulating multiple sensory information processing pathways, and its roles in the brain have been associated with prosocial, maternal, and feeding-related behaviors. Visual information is necessary for initiating these behaviors, with the retina consisting of the first stage in the visual system mediating external stimulus perception. Oxytocin has been detected in the mammalian retina; however, the expression and possible function of oxytocin receptors (OxtR) in the retina remain unknown. Here, we explore the role of oxytocin in regulating visual information processing in the retina.We observed that OxtR mRNA and protein are expressed in the mouse retina. With Oxtr-Cre transgenic mice, immunostaining, and fluorescence in situ hybridization, we found that OxtRs are mainly expressed in GABAergic amacrine cells (ACs) in both the inner nuclear layer (INL) and ganglion cell layer (GCL). Further immunoreactivity studies showed that GABAergic OxtR+ neurons are mainly cholinergic and dopaminergic neurons in the INL and are cholinergic and corticotrophin-releasing hormone neurons in the GCL. Surprisingly, a high level of Oxtr mRNAs was detected in retinal dopaminergic neurons, and exogenous oxytocin application activated dopaminergic neurons to elevate the retinal dopamine level. Relying on in vivo electroretinographic recording, we found that activating retinal OxtRs reduced the activity of bipolar cells via OxtRs and dopamine receptors.These data indicate the functional expression of OxtRs in retinal GABAergic ACs, especially dopaminergic ACs, and expand the interactions between oxytocinergic and dopaminergic systems. This study suggests that visual perception, from the first stage of information processing in the retina, is modulated by hypothalamic oxytocin signaling.
British journal of pharmacology
Li, L;Li, P;Guo, J;Wu, Y;Zeng, Q;Li, N;Huang, X;He, Y;Ai, W;Sun, W;Liu, T;Xiong, D;Xiao, L;Sun, Y;Zhou, Q;Kuang, H;Wang, Z;Jiang, C;
PMID: 36702458 | DOI: 10.1111/bph.16042
Currently, chemotherapy-induced neuropathic pain (CINP) has limited effective treatment. The roles of Oxytocin (OXT) and the oxytocin receptor (OXTR) in central analgesia have been well documented. However, the expression and function of OXTR in the peripheral nervous system remain unclear. Here, we evaluated the peripheral antinociceptive profiles of OXTR in CINP.Paclitaxel (PTX) was used to establish CINP. qRT-PCR, in-situ hybridization, and immunohistochemistry were used to observe the properties of OXTR expression in the dorsal root ganglion (DRG). The antinociceptive effects were assessed by the hot-plate and Von-Frey tests. The whole-cell patch-clamp was performed to record the sodium currents, the excitability of DRG neurons, and the excitatory synapse transmissions.The expression of OXTR in DRG neurons was boosted significantly after PTX treatment. The activation of OXTR exhibited antinociceptive effects and decreased the hyperexcitability of DRG neurons in PTX-treated mice. Additionally, the OXTR activation upregulated the phosphorylation of protein kinase C (pPKC), and in turn impaired the voltage-gated sodium current, especially Nav 1.7 current which performs an indispensable role in PTX-induced neuropathic pain. Oxytocin also suppressed the excitatory transmission in the spinal dorsal horn and the excitatory inputs from the primary afferents in PTX-treated mice.The OXTR in small-sized DRG neurons is upregulated in CINP and the activation of OXTR relieved CINP by inhibiting the neural excitability by an impairment in NaV 1.7 currents via pPKC. Our results suggested that OXTR on peripheral sensory neurons can be a potential target to relieve CINP.This article is protected by
Brain Struct Funct. 2018 Oct 28.
Albert-Gasco H, Sanchez-Sarasua S, Ma S, García-Díaz C, Gundlach AL, Sanchez-Perez AM, Olucha-Bordonau FE.
PMID: 30368554 | DOI: 10.1007/s00429-018-1763-5
In mammals, the extended amygdala is a neural hub for social and emotional information processing. In the rat, the extended amygdala receives inhibitory GABAergic projections from the nucleus incertus (NI) in the pontine tegmentum. NI neurons produce the neuropeptide relaxin-3, which acts via the Gi/o-protein-coupled receptor, RXFP3. A putative role for RXFP3 signalling in regulating social interaction was investigated by assessing the effect of intracerebroventricular infusion of the RXFP3 agonist, RXFP3-A2, on performance in the 3-chamber social interaction paradigm. Central RXFP3-A2, but not vehicle, infusion, disrupted the capacity to discriminate between a familiar and novel conspecific subject, but did not alter differentiation between a conspecific and an inanimate object. Subsequent studies revealed that agonist-infused rats displayed increased phosphoERK(pERK)-immunoreactivity in specific amygdaloid nuclei at 20 min post-infusion, with levels similar to control again after 90 min. In parallel, we used immunoblotting to profile ERK phosphorylation dynamics in whole amygdala after RXFP3-A2 treatment; and multiplex histochemical labelling techniques to reveal that after RXFP3-A2 infusion and social interaction, pERK-immunopositive neurons in amygdala expressed vesicular GABA-transporter mRNA and displayed differential profiles of RXFP3 and oxytocin receptor mRNA. Overall, these findings demonstrate that central relaxin-3/RXFP3 signalling can modulate social recognition in rats via effects within the amygdala and likely interactions with GABA and oxytocin signalling.
Tan Y, Singhal SM, Harden SW, Cahill KM, Nguyen DM, Colon-Perez LM, Sahagian TJ, Thinschmidt JS, de Kloet AD, Febo M, Frazier CJ, Krause EG.
PMID: 30804095 | DOI: 10.1523/JNEUROSCI.2944-18.2019
Social recognition, the ability to recognize individuals that were previously encountered, requires complex integration of sensory inputs with previous experience. Here, we use a variety of approaches to discern how oxytocin sensitive neurons in the prefrontal cortex (PFC) exert descending control over a circuit mediating social recognition in mice. Using male mice with Cre-recombinase directed to the oxytocin receptor gene (Oxtr), we revealed that the Oxtr is expressed on glutamatergic neurons in the PFC, optogenetic stimulation of which, elicited activation of neurons residing in several mesolimbic brain structures. Optogenetic stimulation of axons in the basolateral amygdala (BLA) arising from Oxtr-expressing neurons in the PFC eliminated the ability to distinguish novel from familiar conspecifics, but remarkably, distinguishing between novel and familiar objects was unaffected. These results suggest that an oxytocin sensitive PFC to BLA circuit is required for social recognition. The implication is that impaired social memory may manifest from dysregulation of this circuit.SIGNIFICANCE STATEMENTUsing mice we demonstrate that optogenetic activation of the neurons in the prefrontal cortex (PFC) that express the oxytocin receptor gene (Oxtr) impairs the ability to distinguish between novel and familiar conspecifics but the ability to distinguish between novel and familiar objects remains intact. Subjects with Autism Spectrum Disorders (ASD) have difficulty identifying a person based on remembering facial features; however, ASD and typical subjects perform similarly when remembering objects. In subjects with ASD, viewing the same face increases neural activity in the PFC, which may be analogous to the optogenetic excitation of Oxtr-expressing neurons in the PFC that impairs social recognition in mice. The implication is that over-activation of Oxtr-expressing neurons in the PFC may contribute to ASD symptomology.
Li, J;Ryabinin, A;
| DOI: 10.2139/ssrn.4033172
The centrally-projecting Edinger-Westphal nucleus (EWcp) has been shown to contribute to regulation of multiple functions, including responses to stress and fear, attention, food consumption, addiction, body temperature and maternal behaviors. However, receptors involved in regulation of these behaviors through EWcp remain poorly characterized. On the other hand, the oxytocin peptide (OXT) is also known to regulate a substantial number of physiological responses and behaviors. Here we show that OXT receptors (OXTR) are expressed in EWcp of male and female C57BL/6J mice. These receptors are present on urocortin 1 (UCN)-containing neurons of EWcp and, to a lesser extent, on neurons expressing the vesicular glutamate transporter 2 (vGlut2) of EWcp. Using RNAscope in situ hybridization, we show that UCN and vGlut2 are two intermingled but independent subpopulations of EWcp and characterize their relationship with other populations of neurons in the EWcp. Using immunohistochemistry, we show that intraperitoneal (IP) administration of OXT can induce c-Fos in OXTR-containing neurons of EWcp, suggesting that these receptors on EWcp neurons are functional. A follow up study showed that injection of a dose of OXT (7.7 mg/kg, IP) capable of inducing c-Fos in EWcp also results in temporary hypothermia in mice, while a lower dose (2.3 mg/kg, IP) results in a weaker hypothermia. These studies for the first time describe the EWcp as a site of functionally-significant expression of OXTR. The contribution of these receptors to regulation of various functions of EWcp and OXT needs to be deciphered.
Inoue, YU;Miwa, H;Hori, K;Kaneko, R;Morimoto, Y;Koike, E;Asami, J;Kamijo, S;Yamada, M;Hoshino, M;Inoue, T;
PMID: 35082173 | DOI: 10.1523/ENEURO.0423-21.2022
The neuropeptide oxytocin (Oxt) plays important roles in modulating social behaviors. Oxt receptor (Oxtr) is abundantly expressed in the brain and its relationship to socio-behavioral controls has been extensively studied using mouse brains. Several genetic tools to visualize and/or manipulate Oxtr-expressing cells, such as fluorescent reporters and Cre recombinase drivers, have been generated by ES-cell based gene targeting or bacterial artificial chromosome (BAC) transgenesis. However, these mouse lines displayed some differences in their Oxtr expression profiles probably because of the complex context and integrity of their genomic configurations in each line. Here, we apply our sophisticated genome-editing techniques to the Oxtr locus, systematically generating a series of knock-in mouse lines, in which its endogenous transcriptional regulations are intactly preserved and evaluate their expression profiles to ensure the reliability of our new tools. We employ the epitope tagging strategy, with which C-terminally fused tags can be detected by highly specific antibodies, to successfully visualize the Oxtr protein distribution on the neural membrane with super-resolution imaging for the first time. By using T2A self-cleaving peptide sequences, we also induce proper expressions of tdTomato reporter, codon-improved Cre recombinase (iCre), and spatiotemporally inducible Cre-ERT2 in Oxtr-expressing neurons. Electrophysiological recordings from tdTomato-positive cells in the reporter mice support the validity of our tool design. Retro-orbital injections of AAV-PHP.eB vector into the Cre line further enabled visualization of recombinase activities in the appropriate brain regions. Moreover, the first-time Cre-ERT2 line drives Cre-mediated recombination in a spatiotemporally controlled manner on tamoxifen (TMX) administration. These tools thus provide an excellent resource for future functional studies in Oxt-responsive neurons and should prove of broad interest in the field.
Brain structure & function
Powell, JM;Inoue, K;Wallace, KJ;Seifert, AW;Young, LJ;Kelly, AM;
PMID: 36271259 | DOI: 10.1007/s00429-022-02581-z
The nonapeptide system modulates numerous social behaviors through oxytocin and vasopressin activation of the oxytocin receptor (OXTR) and vasopressin receptor (AVPR1A) in the brain. OXTRs and AVPR1As are widely distributed throughout the brain and binding densities exhibit substantial variation within and across species. Although OXTR and AVPR1A binding distributions have been mapped for several rodents, this system has yet to be characterized in the spiny mouse (Acomys cahirinus). Here we conducted receptor autoradiography and in situ hybridization to map distributions of OXTR and AVPR1A binding and Oxtr and Avpr1a mRNA expression throughout the basal forebrain and midbrain of male and female spiny mice. We found that nonapeptide receptor mRNA is diffuse throughout the forebrain and midbrain and does not always align with OXTR and AVPR1A binding. Analyses of sex differences in brain regions involved in social behavior and reward revealed that males exhibit higher OXTR binding densities in the lateral septum, bed nucleus of the stria terminalis, and anterior hypothalamus. However, no association with gonadal sex was observed for AVPR1A binding. Hierarchical clustering analysis further revealed that co-expression patterns of OXTR and AVPR1A binding across brain regions involved in social behavior and reward differ between males and females. These findings provide mapping distributions and sex differences in nonapeptide receptors in spiny mice. Spiny mice are an excellent organism for studying grouping behaviors such as cooperation and prosociality, and the nonapeptide receptor mapping here can inform the study of nonapeptide-mediated behavior in a highly social, large group-living rodent.
The Journal of comparative neurology
Inoue, K;Ford, CL;Horie, K;Young, LJ;
PMID: 35763609 | DOI: 10.1002/cne.25382
Oxytocin regulates social behavior via direct modulation of neurons, regulation of neural network activity, and interaction with other neurotransmitter systems. The behavioral effects of oxytocin signaling are determined by the species-specific distribution of brain oxytocin receptors. The socially monogamous prairie vole has been a useful model organism for elucidating the role of oxytocin in social behaviors, including pair bonding, response to social loss, and consoling. However, there has been no comprehensive mapping of oxytocin receptor-expressing cells throughout the prairie vole brain. Here, we employed a highly sensitive in situ hybridization, RNAscope, to construct an exhaustive, brain-wide map of oxytocin receptor mRNA-expressing cells. We found that oxytocin receptor mRNA expression was widespread and diffused throughout the brain, with specific areas displaying a particularly robust expression. Comparing receptor binding with mRNA revealed that regions of the hippocampus and substantia nigra contained oxytocin receptor protein but lacked mRNA, indicating that oxytocin receptors can be transported to distal neuronal processes, consistent with presynaptic oxytocin receptor functions. In the nucleus accumbens, a region involved in oxytocin-dependent social bonding, oxytocin receptor mRNA expression was detected in both the D1 and D2 dopamine receptor-expressing subtypes of cells. Furthermore, natural genetic polymorphisms robustly influenced oxytocin receptor expression in both D1 and D2 receptor cell types in the nucleus accumbens. Collectively, our findings further elucidate the extent to which oxytocin signaling is capable of influencing brain-wide neural activity, responses to social stimuli, and social behavior. KEY POINTS: Oxytocin receptor mRNA is diffusely expressed throughout the brain, with strong expression concentrated in certain areas involved in social behavior. Oxytocin receptor mRNA expression and protein localization are misaligned in some areas, indicating that the receptor protein may be transported to distal processes. In the nucleus accumbens, oxytocin receptors are expressed on cells expressing both D1 and D2 dopamine receptor subtypes, and the majority of variation in oxytocin receptor expression between animals is attributable to polymorphisms in the oxytocin receptor gene.
Raam T, McAvoy KM, Besnard A, Veenema A, Sahay A.
PMID: 29222469 | DOI: 10.1038/s41467-017-02173-0
Oxytocin receptor (Oxtr) signaling in neural circuits mediating discrimination of social stimuli and affiliation or avoidance behavior is thought to guide social recognition. Remarkably, the physiological functions of Oxtrs in the hippocampus are not known. Here we demonstrate using genetic and pharmacological approaches that Oxtrs in the anterior dentate gyrus (aDG) and anterior CA2/CA3 (aCA2/CA3) of mice are necessary for discrimination of social, but not non-social, stimuli. Further, Oxtrs in aCA2/CA3 neurons recruit a population-based coding mechanism to mediate social stimuli discrimination. Optogenetic terminal-specific attenuation revealed a critical role for aCA2/CA3 outputs to posterior CA1 for discrimination of social stimuli. In contrast, aCA2/CA3 projections to aCA1 mediate discrimination of non-social stimuli. These studies identify a role for an aDG-CA2/CA3 axis of Oxtr expressing cells in discrimination of social stimuli and delineate a pathway relaying social memory computations in the anterior hippocampus to the posterior hippocampus to guide social recognition.
Li, L;Durand-de Cuttoli, R;Aubry, AV;Burnett, CJ;Cathomas, F;Parise, LF;Chan, KL;Morel, C;Yuan, C;Shimo, Y;Lin, HY;Wang, J;Russo, SJ;
PMID: 36450985 | DOI: 10.1038/s41586-022-05484-5
In humans, traumatic social experiences can contribute to psychiatric disorders1. It is suggested that social trauma impairs brain reward function such that social behaviour is no longer rewarding, leading to severe social avoidance2,3. In rodents, the chronic social defeat stress (CSDS) model has been used to understand the neurobiology underlying stress susceptibility versus resilience following social trauma, yet little is known regarding its impact on social reward4,5. Here we show that, following CSDS, a subset of male and female mice, termed susceptible (SUS), avoid social interaction with non-aggressive, same-sex juvenile C57BL/6J mice and do not develop context-dependent social reward following encounters with them. Non-social stressors have no effect on social reward in either sex. Next, using whole-brain Fos mapping, in vivo Ca2+ imaging and whole-cell recordings, we identified a population of stress/threat-responsive lateral septum neurotensin (NTLS) neurons that are activated by juvenile social interactions only in SUS mice, but not in resilient or unstressed control mice. Optogenetic or chemogenetic manipulation of NTLS neurons and their downstream connections modulates social interaction and social reward. Together, these data suggest that previously rewarding social targets are possibly perceived as social threats in SUS mice, resulting from hyperactive NTLS neurons that occlude social reward processing.
