Dopamine cell loss and increased iron in the substantia nigra (SN) characterize Parkinson's disease (PD), with cerebellar involvement increasingly recognized, particularly in motor compensation and levodopa-induced dyskinesia (LID) development. Because the red nucleus (RN) mediates cerebellar circuitry, we hypothesized that RN iron changes might reflect cerebellum-related compensation, and/or the intrinsic capacity for LID development. We acquired high resolution magnetic resonance images from 23 control and 38 PD subjects (12 with PD and history of LID [PD+DYS]) and 26 with PD and no history of LID (PD-DYS). Iron content was estimated from bilateral RN and SN transverse relaxation rates (R2*). PD subjects overall displayed higher R2* values in both the SN and RN. RN R2* values correlated with off-drug Unified Parkinson's Disease Rating Scale-motor scores, but not disease duration or drug dosage. RN R2* values were significantly higher in PD+DYS compared with control and PD-DYS subjects; control and PD-DYS subjects did not differ. The association of higher RN iron content with PD-related dyskinesia suggests increased iron content is involved in, or reflects, greater cerebellar compensatory capacity and thus increased likelihood of LID development.

No study has investigated red nucleus (RN) atrophy in multiple sclerosis (MS) despite cerebellum and its connections are elective sites of MS-related pathology. In this study, we explore RN atrophy in early MS phases and its association with cerebellar damage (focal lesions and atrophy) and physical disability. Thirty-seven relapse-onset MS (RMS) patients having mean age of 35.6 ± 8.5 (18-56) years and mean disease duration of 1.1 ± 1.5 (0-5) years, and 36 age- and sex-matched healthy controls (HC) were studied. Cerebellar and RN lesions and volumes were analyzed on 3 T-MRI images. RMS did not differ from HC in cerebellar lobe volumes but significantly differed in both right (107.84 ± 13.95 mm3 vs. 99.37 ± 11.53 mm3 , p = .019) and left (109.71 ± 14.94 mm3 vs. 100.47 ± 15.78 mm3 , p = .020) RN volumes. Cerebellar white matter lesion volume (WMLV) inversely correlated with both right and left RN volumes (r = -.333, p = .004 and r = -.298, p = .010, respectively), while no correlation was detected between RN volumes and mean cortical thickness, cerebellar gray matter lesion volume, and supratentorial WMLV (right RN: r = -.147, p = .216; left RN: r = -.153, p = .196). Right, but not left, RN volume inversely correlated with midbrain WMLV (r = -.310, p = .008), while no correlation was observed between whole brainstem WMLV and either RN volumes (right RN: r = -.164, p = .164; left RN: r = -.64, p = .588). Finally, left RN volume correlated with vermis VIIb (r = .297, p = .011) and right interposed nucleus (r = .249, p = .034) volumes. We observed RN atrophy in early RMS, likely resulting from anterograde axonal degeneration starting in cerebellar and midbrain WML. RN atrophy seems a promising marker of neurodegeneration and/or cerebellar damage in RMS.

Previous Diffusion Tensor Imaging studies have demonstrated that the human red nucleus is widely interconnected with sensory-motor and prefrontal cortices. In this study, we assessed red nucleus connectivity by using a multi-tensor model called non- negative Constrained Spherical Deconvolution (CSD), which is able to resolve more than one fiber orientation per voxel. Connections of the red nuclei of fifteen volunteers were studied at 3T using CSD axonal tracking. We found significant connectivity between RN and the following cortical and subcortical areas: cerebellar cortex, thalamus, paracentral lobule, postcentral gyrus, precentral gyrus, superior frontal gyrus and dentate nucleus. We confirmed that red nucleus is tightly linked with the cerebral cortex and has dense subcortical connections with thalamus and cerebellar cortex. These findings may be useful in a clinical context considering that RN is involved in motor control and it is known to have potential to compensate for injury of the corticospinal tract.

The ability to adjust behavior is an essential component of cognitive control. Much is known about frontal and striatal processes that support cognitive control, but few studies have investigated how motor signals change during reactive and proactive adjustments in motor output. To address this, we characterized neural signals in red nucleus (RN), a brain region linked to motor control, as male and female rats performed a novel variant of the stop-signal task. We found that activity in RN represented the direction of movement and was strongly correlated with movement speed. Additionally, we found that directional movement signals were amplified on STOP trials before completion of the response and that the strength of RN signals was modulated when rats exhibited cognitive control. These results provide the first evidence that neural signals in RN integrate cognitive control signals to reshape motor outcomes reactively within trials and proactivity across them.SIGNIFICANCE STATEMENT Healthy human behavior requires the suppression or inhibition of errant or maladaptive motor responses, often called cognitive control. While much is known about how frontal brain regions facilitate cognitive control, less is known about how motor regions respond to rapid and unexpected changes in action selection. To address this, we recorded from neurons in the red nucleus, a motor region thought to be important for initiating movement in rats performing a cognitive control task. We show that red nucleus tracks motor plans and that selectivity was modulated on trials that required shifting from one motor response to another. Collectively, these findings suggest that red nucleus contributes to modulating motor behavior during cognitive control.

With recent developments in MR acquisition at 7T, smaller brainstem structures such as the red nuclei, substantia nigra and subthalamic nuclei can be imaged with good contrast and resolution. These structures have important roles both in the study of the healthy brain and in diseases such as Parkinson's disease, but few methods have been described to automatically segment them. In this paper, we extend a method that we have previously proposed for segmentation of the striatum and globus pallidus to segment these deeper and smaller structures. We modify the method to allow more direct control over segmentation smoothness by using a Markov random field prior. We investigate segmentation performance in three age groups and show that the method produces consistent results that correspond well with manual segmentations. We perform a vertex-based analysis to identify changes with age in the shape of the structures and present results suggesting that the method may be at least as effective as manual delineation in capturing differences between subjects.

Rhodophytes (red algae) are a diverse group of algae with great ecological and economic importance. However, tools for post-genomic research on red algae are still largely lacking. Here, we report the development of an efficient genetic transformation system for the model rhodophyte Porphyridium purpureum. We show that transgenes can be expressed to unprecedented levels of up to 5% of the total soluble protein. Surprisingly, the transgenic DNA is maintained episomally, as extrachromosomal high-copy number plasmid. The bacterial replication origin confers replication in the algal nucleus, thus providing an intriguing example of a prokaryotic replication origin functioning in a eukaryotic system. The extended presence of bacterial episomal elements may provide an evolutionary explanation for the frequent natural occurrence of extrachromosomal plasmids in red algae, and may also have contributed to the high rate of horizontal gene transfer from bacteria to the nuclear genome of Porphyridium purpureum and other rhodophytes.

Previous studies have speculated that brain activity directly controls immune responses in lymphoid organs. However, the upstream brain regions that control lymphoid organs and how they interface with lymphoid organs to produce stress-induced anxiety-like behavior remain elusive. Using stressed human participants and rat models, we show that CCL5 levels are increased in stressed individuals compared to controls. Stress-inducible CCL5 is mainly produced from cervical lymph nodes (CLN). Retrograde tracing from CLN identifies glutamatergic neurons in the red nucleus (RN), the activities of which are tightly correlated with CCL5 levels and anxiety-like behavior in male rats. Ablation or chemogenetic inhibition of RN glutamatergic neurons increases anxiety levels and CCL5 expression in the serum and CLNs, whereas pharmacogenetic activation of these neurons reduces anxiety levels and CCL5 synthesis after restraint stress exposure. Chemogenetic inhibition of the projection from primary motor cortex to RN elicits anxiety-like behavior and CCL5 synthesis. This brain-lymph node axis provides insights into lymph node tissue as a stress-responsive endocrine organ.

This study aimed to examine the functional networks related to the extrapyramidal system using a temporal oscillation signal correlation analysis method based on critical nodes in the substantia nigra (SN), red nucleus (RN) and dentate nucleus (DN). Nineteen healthy subjects underwent resting-state fMRI and susceptibility weighted imaging (SWI). For the brain network analysis, the SN, RN and DN were positioned on susceptibility weighted images and used as seeds for temporal correlations analyzed via BOLD data. T-tests were performed for the correlation coefficients of each seed. We demonstrated that the SN, RN and DN were functionally connected to each other, and, in general, their connectivity maps overlapped in a series of subcortical extrapyramidal structures and regions of cerebral cortices. A Granger causality analysis indicated that the effective connectivity graphs within extrapyramidal structures mainly exhibited a spacial up-down pattern for the positive and negative influences, respectively. Our findings suggest that extensive regions involved in the extrapyramidal system constituted a relatively exclusive network via spatial-temporal correlation signals that analogously corresponded to the anatomical structures. The investigation of extrapyramidal system networks may have potential clinical implications.

Functional connectivity (FC) has been used to investigate the pathophysiology of migraine. Accumulating evidence is pointing toward malfunctioning of brainstem structures, i.e., the red nucleus (RN) and substantia nigra (SN), as an important factor in migraine without aura (MwoA). We aimed to identify atypical FC between the RN and SN and other brain areas in patients with MwoA and to explore the association between RN and SN connectivity changes and performance on neuropsychological tests in these patients.

The Red Nucleus (RN) is a large nucleus located in the ventral midbrain: it is subdivided into a small caudal magnocellular part (mRN) and a large rostral parvocellular part (pRN). These distinct structural regions are part of functionally different networks and show distinctive connectivity features: the mRN is connected to the interposed nucleus, whilst the pRN is mainly connected to dentate nucleus, cortex and inferior olivary complex. Despite functional neuroimaging studies suggest RN involvement in complex motor and higher order functions, the pRN and mRN cannot be distinguished using conventional MRI. Herein, we employ high-quality structural and diffusion MRI data of 100 individuals from the Human Connectome Project repository and constrained spherical deconvolution tractography to perform connectivity-based segmentation of the human RN. In particular, we tracked connections of RN with the inferior olivary complex, the interposed nucleus, the dentate nucleus and the cerebral cortex. We found that the RN can be subdivided according to its connectivity into two clusters: a large ventrolateral one, mainly connected with the cerebral cortex and the inferior olivary complex, and a smaller dorsomedial one, mainly connected with the interposed nucleus. This structural topography strongly reflects the connectivity patterns of pRN and mRN respectively. Structural connectivity-based segmentation could represent a useful tool for the identification of distinct subregions of the human red nucleus on 3T MRI thus allowing a better evaluation of this subcortical structure in healthy and pathological conditions.

The pontine oral reticular nucleus, gigantocellular reticular nucleus (Gi) and dorsal paragigantocellular nucleus (DPGi) of the medulla are key elements of a brainstem-reticulospinal inhibitory system that participates in rapid eye movement (REM) sleep atonia. Our recent study has shown that excitation of these brainstem nuclei in decerebrate rats inhibits locus coeruleus cells and the midbrain locomotor region neurons related to muscle tone facilitation. In the present study we have examined the influences of electrical and chemical stimulation of Gi and DPGi inhibitory sites on the activity of neurons located in the magnocellular part of the red nucleus (RMC), a cell group that participates in both the tonic and phasic regulation of motor output. A total of 192 RMC neurons were recorded in precollicular-premammillary decerebrate rats with muscle rigidity and induced locomotion. Thirty-three RMC neurons were identified antidromically as rubrospinal (RMC-spinal) cells by stimulation of the contralateral dorsolateral funiculus at the L2 level. A total of 141 RMC neurons (88.7 %) and all RMC-spinal neurons were inhibited during electrical stimulation of Gi and DPGi inhibitory sites. This cessation of activity was correlated with bilateral muscle atonia or blockage of locomotion. Six RMC cells (3.8 %) were excited (224 +/- 50 %, n = 6, minimum = 98, maximum = 410, P < 0.05) and 11 cells (7 %) gave no response to Gi and DPGi stimulation. Microinjections of kainic acid (100 microM, 0.2 microl) into Gi and DPGi inhibitory sites, previously identified by electrical stimulation, produced a short-latency (35 +/- 3.5 s, n = 11) decrease of rigid hindlimb muscle tone and inhibition of all tested RMC (n = 7) and RMC-spinal (n = 5) neurons. These results, combined with our recent published data, suggest that inhibition of motor function during activation of the brainstem inhibitory system is related to both the descending inhibition of spinal motoneurons and suppression of activity in supraspinal motor facilitatory systems. These two mechanisms acting synergistically may cause generalized motor inhibition during REM sleep and cataplexy.

We previously reported that interleukin-1β (IL-1β) in the red nucleus (RN) is involved in pain modulation and exerts a facilitatory effect in the development of neuropathic pain. Here, we explored the actions of signaling pathways, including the Janus kinase/signal transducer and activator of transcription 3 (JAK/STAT3), c-Jun N-terminal kinase (JNK), extracellular signal-regulated kinase (ERK), p38 mitogen-activated protein kinase (p38 MAPK) and nuclear factor-κB (NF-κB) pathways, on RN IL-1β-mediated pain modulation. After a single dose of recombinant rat IL-1β (rrIL-1β, 10 ng) injected into the RN in normal rats, a tactile allodynia was evoked in the contralateral but not ipsilateral hindpaw, commencing 75 min and peaking 120 min postinjection. Up-regulated protein levels of phospho-STAT3 (p-STAT3) and p-JNK were observed in the RN 120 min after rrIL-1β injection, the increases of p-STAT3 and p-JNK were blocked by anti-IL-1β antibody. However, the expression levels of p-ERK, p-p38 MAPK, and NF-κB in the RN were not affected by rrIL-1β injection. RN neurons and astrocytes contributed to IL-1β-evoked up-regulation of p-STAT3 and p-JNK. Further studies demonstrated that injection of the JAK2 antagonist AG490 or JNK antagonist SP600125 into the RN 30 min prior to the administration of rrIL-1β could completely prevent IL-1β-evoked tactile allodynia, while injection of the ERK antagonist PD98059, p38 MAPK antagonist SB203580, or NF-κB antagonist PDTC did not affect IL-1β-evoked tactile allodynia. In conclusion, our data provide additional evidence that RN IL-1β is involved in pain modulation, and that it exerts a facilitatory effect by activating the JAK/STAT3 and JNK signaling pathways.

Target recognition by developing axons is one of the fundamental steps for establishing the proper pattern of neuronal connectivity during development. However, knowledge of the mechanisms that underlie this critical event is still limited. In this study, to examine how commissural axons in vertebrates recognize their targets after crossing the midline, we analyzed in detail the behavior of postcrossing commissural axons derived from the deep cerebellar nuclei (DCN) in the developing mouse cerebellum. For this, we employed a cell-type-specific genetic labeling approach to selectively visualize DCN axons during the time when these axons project to the red nucleus (RN), one of the well-characterized targets of DCN axons. We found that, when DCN axons initially entered the RN at its caudal end, these axons continued to grow rostrally through the RN without showing noticeable morphological signs of axon branching. Interestingly, after a delay, DCN axons started forming interstitial branches from the portion of the axon shaft selectively within the RN. Because commissural axons acquire responsiveness to several guidance cues when they cross the midline, we further addressed whether midline crossing is a prerequisite for subsequent targeting by using a Robo3 knockdown strategy. We found that DCN axons were still capable of forming interstitial branches within the RN even in the absence of midline crossing. These results therefore suggest that the mechanism of RN recognition by DCN axons involves a delayed interstitial branching, and that these axons possess an intrinsic ability to respond to the target-derived cues irrespective of midline crossing.

Previous studies have demonstrated that the red nucleus (RN) participates in the modulation of neuropathic pain and plays both a facilitated role by pro-inflammatory cytokines, such as tumor necrosis factor-alpha (TNF-α) and interleukin-1β (IL-1β), and an inhibitory role through the anti-inflammatory cytokine IL-10. In this study, we sought to investigate the expressions and roles of transforming growth factor-beta (TGF-β), a potent anti-inflammatory cytokine, as well as its type 1 receptor (TGF-β-R1) in the RN in normal and neuropathic pain rats. Immunohistochemistry showed that TGF-β and TGF-β-R1 were constitutively expressed in the RN of normal rats, and co-localized with neurons and all three glial cell types, astrocytes, microglia and oligodendrocytes. Following spared nerve injury (SNI), the expression levels of TGF-β and TGF-β-R1 were significantly down-regulated in the RN contralateral (but not ipsilateral) to the nerve injury side of rats at one week and reached the lowest level at two weeks after SNI, and both of them were co-localized with neurons and oligodendrocytes but not with astrocytes and microglia. Microinjection of different doses of anti-TGF-β antibody (250, 125, 50 ng) into the unilateral RN of normal rats dose-dependently decreased the mechanical withdrawal threshold of contralateral (but not ipsilateral) hind paw and induced significant mechanical hypersensitivity, which was similar to mechanical allodynia induced by peripheral nerve injury. In contrast, microinjection of different doses of recombinant rat TGF-β1 (500, 250, 100 ng) into the RN contralateral to the nerve injury side of SNI rats dose-dependently increased the paw withdrawal threshold and significantly alleviated mechanical allodynia induced by SNI. These results suggest that TGF-β in the RN participates in nociceptive processing and plays antinociceptive effects under normal physiological condition and in the development of neuropathic pain induced by SNI.

Previous studies have demonstrated that glutamate plays an important role in the development of pathological pain. This study investigates the expression changes of glutamate and the roles of different types of glutamate receptors in the red nucleus (RN) in the development of neuropathic allodynia induced by spared nerve injury (SNI). Immunohistochemistry indicated that glutamate was constitutively expressed in the RN of normal rats. After SNI, the expression levels of glutamate were significantly increased in the RN at 1 week and reached the highest level at 2 weeks postinjury compared with sham-operated and normal rats. The RN glutamate was colocalized with neurons, oligodendrocytes, and astrocytes but not microglia under physiological and neuropathic pain conditions. To elucidate further the roles of the RN glutamate and different types of glutamate receptors in the development of neuropathic allodynia, antagonists to N-methyl-D-aspartate (NMDA), non-NMDA, or metabotropic glutamate receptors (mGluRs) were microinjected into the RN contralateral to the nerve-injury side of rats with SNI, and the paw withdrawal threshold (PWT) was dynamically assessed with von Frey filaments. Microinjection of the NMDA receptor antagonist MK-801 into the RN did not show any effect on SNI-induced mechanical allodynia. However, microinjection of the non-NMDA receptor antagonist 6,7-dinitroquinoxaline-2,3(1H,4H)-dione or the mGluR antagonist (±)-α-methyl-(4-carboxyphenyl) glycine into the RN significantly increased the PWT and alleviated SNI-induced mechanical allodynia. These findings suggest that RN glutamate is involved in regulating neuropathic pain and facilitates the development of SNI-induced neuropathic allodynia. The algesic effect of glutamate is transmitted by the non-NMDA glutamate receptor and mGluRs.

Physical exercise is rewarding and protective against drug abuse and addiction. However, the neural mechanisms underlying these actions remain unclear. Here, we report that long-term wheel-running produced a more robust increase in c-fos expression in the red nucleus (RN) than in other brain regions. Anatomic and functional assays demonstrated that most RN magnocellular portion (RNm) neurons are glutamatergic. Wheel-running activates a subset of RNm glutamate neurons that project to ventral tegmental area (VTA) dopamine neurons. Optogenetic stimulation of this pathway was rewarding, as assessed by intracranial self-stimulation and conditioned place preference, whereas optical inhibition blocked wheel-running behavior. Running wheel access decreased cocaine self-administration and cocaine seeking during extinction. Last, optogenetic stimulation of the RNm-to-VTA glutamate pathway inhibited responding to cocaine. Together, these findings indicate that physical exercise activates a specific RNm-to-VTA glutamatergic pathway, producing exercise reward and reducing cocaine intake.

Neurological compensatory mechanisms help our brain to adjust to neurodegeneration as in Parkinson's disease. It is suggested that the compensation of the damaged striato-thalamo-cortical circuit is focused on the intact thalamo-rubro-cerebellar pathway as seen during presymptomatic Parkinson, paradoxical movement and sensorimotor rhythm (SMR). Indeed, the size of the red nucleus, connecting the cerebellum with the cerebral cortex, is larger in Parkinson's disease patients suggesting an increased activation of this brain area. Therefore, the red nucleus was examined in MPTP-induced parkinsonian marmoset monkeys during the presymptomatic stage and after SMR activation by neurofeedback training. We found a reverse significant correlation between the early expression of parkinsonian signs and the size of the parvocellular part of the red nucleus, which is predominantly present in human and non-human primates. In quadrupedal animals it consists mainly of the magnocellular part. Furthermore, SMR activation, that mitigated parkinsonian signs, further increased the size of the red nucleus in the marmoset monkey. This plasticity of the brain helps to compensate for dysfunctional movement control and can be a promising target for compensatory treatment with neurofeedback technology, vibrotactile stimulation or DBS in order to improve the quality of life for Parkinson's disease patients.

Assessing the cell-type expression pattern of a certain gene can be achieved by using cell-type-specific gene manipulation. Recently, cre-recombinase-dependent gene-silencing tool, pSico has become popular in neuroscientific research. However, pSico has a critical limitation that gene-silenced cell cannot be identified by fluorescence, due to an excision of the reporter gene for green fluorescence protein (GFP). To overcome this limitation, we newly developed pSico-Red, with mCherry gene as a reporter outside two loxP sites, so that red mCherry signal is detected in all transfected cells. When a cell expresses cre, GFP is excised and shRNA is enabled, resulting in disappearance of GFP. This feature of pSico-Red provides not only cell-type-specific gene-silencing but also identification of cre expressing cells. Using this system, we demonstrated for the first time the neuronal expression of the Bestrophin-1 (Best1) in thalamic reticular nucleus (TRN) and TRN-neuron-specific gene-silencing of Best1. We combined adeno-associated virus (AAV) carrying Best1-shRNA in pSico-Red vector and transgenic mouse expressing cre under the promoter of distal-less homeobox 5/6 (DLX5/6), a marker for inhibitory neurons. Firstly, we found that almost all of inhibitory neurons in TRN express Best1 by immunohistochemistry. Using pSico-Red virus, we found that 80% of infected TRN neurons were DLX5/6-cre positive but parvalbumin negative. Finally, we found that Best1 in DLX5/6-cre positive neurons were significantly reduced by Best1-shRNA. Our study demonstrates that TRN neurons strongly express Best1 and that pSico-Red is a valuable tool for cell-type-specific gene manipulation and identification of specific cell population.

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, 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.

Our previous studies have clarified that red nucleus (RN) interleukin (IL)-6 is involved in the maintenance of neuropathic pain and produces a facilitatory effect by activating JAK2/STAT3 and ERK pathways. In this study, we further explored the immune molecular mechanisms of rubral IL-6-mediated descending facilitation at the spinal cord level. IL-6-evoked tactile allodynia was established by injecting recombinant IL-6 into the unilateral RN of naive male rats. Following intrarubral administration of IL-6, obvious tactile allodynia was evoked in the contralateral hindpaw of rats. Meanwhile, the expressions of pro-inflammatory cytokines tumor necrosis factor-α (TNF-α), IL-1β, and IL-6 were elevated in the contralateral spinal dorsal horn (L4-L6), blocking spinal TNF-α, IL-1β, or IL-6 with neutralizing antibodies relieved IL-6-evoked tactile allodynia. Conversely, the levels of anti-inflammatory cytokines transforming growth factor-β (TGF-β) and IL-10 were reduced in the contralateral spinal dorsal horn (L4-L6), an intrathecal supplement of exogenous TGF-β, or IL-10 attenuated IL-6-evoked tactile allodynia. Further studies demonstrated that intrarubral pretreatment with JAK2/STAT3 inhibitor AG490 suppressed the elevations of spinal TNF-α, IL-1β, and IL-6 and promoted the expressions of TGF-β and IL-10 in IL-6-evoked tactile allodynia rats. However, intrarubral pretreatment with ERK inhibitor PD98059 only restrained the increase in spinal TNF-α and enhanced the expression of spinal IL-10. These findings imply that rubral IL-6 plays descending facilitation and produces algesic effect through upregulating the expressions of spinal pro-inflammatory cytokines TNF-α, IL-1β, and IL-6 and downregulating the expressions of spinal anti-inflammatory cytokines TGF-β and IL-10 by activating JAK2/STAT3 and/or ERK pathways, which provides potential therapeutic targets for the treatment of pathological pain.