Enkephalin-mediated modulation of basal somatic sensitivity by regulatory T cells in mice.

CD4+CD25+Foxp3+ regulatory T cells (Treg) have been implicated in pain modulation in various inflammatory conditions. However, whether Treg cells hamper pain at steady state and by which mechanism is still unclear. From a meta-analysis of the transcriptomes of murine Treg and conventional T cells (Tconv), we observe that the proenkephalin gene (Penk), encoding the precursor of analgesic opioid peptides, ranks among the top 25 genes most enriched in Treg cells. We then present various evidence suggesting that Penk is regulated in part by members of the Tumor Necrosis Factor Receptor (TNFR) family and the transcription factor Basic leucine zipper transcription faatf-like (BATF). Using mice in which the promoter activity of Penk can be tracked with a fluorescent reporter, we also show that Penk expression is mostly detected in Treg and activated Tconv in non-inflammatory conditions in the colon and skin. Functionally, Treg cells proficient or deficient for Penk suppress equally well the proliferation of effector T cells in vitro and autoimmune colitis in vivo. In contrast, inducible ablation of Penk in Treg leads to heat hyperalgesia in both male and female mice. Overall, our results indicate that Treg might play a key role at modulating basal somatic sensitivity in mice through the production of analgesic opioid peptides.

Molecular mechanism of basolateral amygdala involved in electroacupuncture-induced amelioration of cancer pain and concomitant depression based on transcriptomics techniques. / åŸºäºŽè½¬å½•ç»„å­¦æŠ€æœ¯æŽ¢è®¨åŸºåº•å¤–ä¾§æä»æ ¸å‚ä¸Žç”µé’ˆæ²»ç–—ç™Œç—›åŠå ¶è¯±å‘çš„æŠ‘éƒæƒ ç»ªçš„åˆ†å­æœºåˆ¶.

OBJECTIVES: To observe the effect of electroacupuncture (EA) of "Zusanli" (ST36) and "Sanyinjiao" (SP6) on cancer pain and concomitant negative emotion in cancer pain model mice, and to explore its molecular mechanisms in the basolateral amygdala (BLA) by using transcriptomics techniques. METHODS: C57BL/6 mice were randomized into sham operation, model and EA groups, with 10 mice in each group. The cancer pain model was established by injecting PBS suspension containing Lewis lung cancer cells into the femur. The mice in the EA group received EA stimulation(1 mA, 2 Hz) on ST36 and SP6 from the 10th day after modeling, 20 min per day for 12 successive days. The bone damage of the distal femur was observed with X-ray and H.E. staining, respectively. The mechanical pain threshold (MPT) was detected by using von Frey. The depression-like behavior was detected by using sucrose-preference test (sucrose preference index in 12 h), and the immobility (feeling of despair) duration of forced swimming within 4 min. The BLA tissue was extracted for RNA sequencing (RNA library construction, and screening differential gene profiling by transcriptomic sequencing) and bioinformatics analysis. The real-time PCR was used to validate the mRNA expression of differentially expressed genes：tumor necrosis factor superfamily 8 (Tnfsf8), bone marrow stromal cell antigen 1 (Bst1), prodynorphin (Pdyn) and voltage-gated sodium channelß4 (Scn4b). RESULTS: H.E. staining and X-ray showed significant bone damage in the distal femur in cancer pain mice. In contrast to the sham operation group, the MPT on the 1st , 4th, 7th , 10th, 14th and 21st day after modeling and sucrose preference index were significantly decreased (P<0.001, P<0.000 1), and the immobility time of the forced swimming was considerably increased in the model group (P<0.001). In contrast to the model group, the MPT values on the 14th and 21st day and sucrose preference index were obviously increased (P<0.000 1, P<0.05), and the immobility time was strikingly decreased in the EA group (P<0.01). RNA sequencing showed that a total of 404 differentially expressed genes (205 up-regulated, 199 down-regulated) were screened in the model group compared with the sham operation group, and a total of 329 differentially expressed genes (206 up-regulated and 123 down-regulated) were screened in the EA group compared with the model group. Venn diagram analysis of the differentially expressed genes showed that 45 up-regulated and 28 down-regulated genes in the model group were completely reversed by EA. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses of the screened differentially expressed genes revealed that the above differential genes were mainly enriched in the ligand receptor activity, cytokine receptor binding, and cytokine activity related to neuro-inflammation, as well as in neuropeptide signaling pathways related to neuronal excitability, and calcium ion mediated signal transduction. The analysis of KEGG pathway showed that the differentially expressed genes were mainly enriched in the inflammation-related pathways, such as interleukin-17 pathway. Validation analysis of the differentially expressed genes showed that the expression levels of Tnfsf8 and Bst1 were significantly up-regulated in the model group compared with the sham operation group (P<0.01, P<0.05), and down-regulated by EA (P<0.01, P<0.05), while the expression levels of Pdyn and Scn4b were down-regulated in the model group in comparison with the sham operation group (P<0.01), and up-regulated by EA (P<0.05, P<0.01), which was consistent with the changing trend of the gene sequencing results. CONCLUSIONS: Acupuncture of ST36 and SP6 can significantly relieve cancer pain and concomitant negative emotion in cancer pain mice, which may be related to its functions in alleviating neuro-inflammation and relieving the abnormal activities of specific neurons in the BLA.

Evaluation of Kynu, Defb2, Camp, and Penk Expression Levels as Psoriasis Marker in the Imiquimod-Induced Psoriasis Model.

Background: Psoriasis is a noncontagious auto-inflammatory chronic skin disease. So far, some of the inflammatory genes were upregulated in mouse model of psoriasis. This study examined changes in skin mRNA expression of L-kynureninase (Kynu), cathelicidin antimicrobial peptide (Camp), beta-defensin 2 (Defb2), and proenkephalin (Penk) in a mouse model of imiquimod-induced psoriasis. Materials and Methods: Tree groups of C57BL/6 female mice were allocated. The imiquimod (IMQ) cream was administered to the mice dorsal skin of the two groups to induce psoriatic inflammation. In the treatment group, IMQ was administered 10 min after hydrogel-containing M7 anti-IL-17A aptamer treatment. Vaseline (Vas) was administered to the negative control group. The psoriatic skin lesions were evaluated based on the psoriasis area severity index (PASI) score, histopathology, and mRNA expression levels of Kynu, Camp, Defb2, and Penk using real-time PCR. In order to assess the systemic response, the spleen and lymph node indexes were also evaluated. Results: The PASI and epidermal thickness scores were 6.01 and 1.96, respectively, in the IMQ group, and they significantly decreased after aptamer administration to 1.15 and 0.90, respectively (P < 0.05). Spleen and lymph node indexes showed an increase in the IMQ group, followed by a slight decrease after aptamer treatment (P > 0.05). Additionally, the mRNA expression levels of Kynu, Defb2, Camp, and Penk genes in the IMQ-treated region showed a significant 2.70, 4.56, 3.29, and 2.61-fold increase relative to the Vas mice, respectively (P < 0.05). The aptamer-treated region exhibited a significant decrease in these gene expression levels (P < 0.05). A positive correlation was found between Kynu, Penk, and Camp expression levels and erythema, as well as Camp expression with PASI, scaling, and thickness (P < 0.05). Conclusion: According to our results, it seems that Kynu, Camp, and Penk can be considered appropriate markers for the evaluation of psoriasis in IMQ-induced psoriasis. Also, the anti-IL-17 aptamer downregulated these important genes in this mouse model.

Social Isolation Induces Changes in the Monoaminergic Signalling in the Rat Medial Prefrontal Cortex.

(1) Background: The effects of short-term social isolation during adulthood have not yet been fully established in rats behaviourally, and not at all transcriptomically in the medial prefrontal cortex (mPFC). (2) Methods: We measured the behavioural effects of housing adult male rats in pairs or alone for 10 days. We also used RNA sequencing to measure the accompanying gene expression alterations in the mPFC of male rats. (3) Results: The isolated animals exhibited reduced sociability and social novelty preference, but increased social interaction. There was no change in their aggression, anxiety, or depression-like activity. Transcriptomic analysis revealed a differential expression of 46 genes between the groups. The KEGG pathway analysis showed that differentially expressed genes are involved in neuroactive ligand-receptor interactions, particularly in the dopaminergic and peptidergic systems, and addiction. Subsequent validation confirmed the decreased level of three altered genes: regulator of G protein signalling 9 (Rgs9), serotonin receptor 2c (Htr2c), and Prodynorphin (Pdyn), which are involved in dopaminergic, serotonergic, and peptidergic function, respectively. Antagonizing Htr2c confirmed its role in social novelty discrimination. (4) Conclusions: Social homeostatic regulations include monoaminergic and peptidergic systems of the mPFC.

Genetic Variants in KNDy Pathway Lack Association with Premature Ovarian Insufficiency in Mexican Women: A Sequencing-Based Cohort Study.

Previous studies have demonstrated the essential role of the Kisspeptin/Neurokinin B/Dynorphin A (KNDy) pathway in female reproductive biology by regulating the activity of the hypothalamic-pituitary-gonadal axis. Identified loss-of-function mutations in these genes are linked to various reproductive disorders. This study investigated genetic disorders linked to mutations in the KNDy genes related to premature ovarian insufficiency (POI). A cohort of 14 Mexican POI patients underwent genetic screening using PCR-SSCP and Sanger sequencing, assessing the genetic variations' impact on protein function thereafter using multiple in silico tools. The PCR excluded extensive deletions, insertions, and duplications, while SSCP detected five genetic variants. Variations occurred in the KISS1 (c.58G>A and c.242C>G), KISS1R (c.1091A>T), PDYN (c.600C>T), and OPRK1 (c.36G>T) genes, whereas no genetic anomalies were found in NK3/NK3R genes. Each single-nucleotide variant underwent genotyping using PCR-SSCP in 100 POI-free subjects. Their allelic frequencies paralleled the patient group. These observations indicate that allelic variations in the KNDy genes may not contribute to POI etiology. Hence, screening for mutations in KNDy genes should not be a part of the diagnostic protocol for POI.

A single-vector intersectional AAV strategy for interrogating cellular diversity and brain function.

As discovery of cellular diversity in the brain accelerates, so does the need for tools that target cells based on multiple features. Here we developed Conditional Viral Expression by Ribozyme Guided Degradation (ConVERGD), an adeno-associated virus-based, single-construct, intersectional targeting strategy that combines a self-cleaving ribozyme with traditional FLEx switches to deliver molecular cargo to specific neuronal subtypes. ConVERGD offers benefits over existing intersectional expression platforms, such as expanded intersectional targeting with up to five recombinase-based features, accommodation of larger and more complex payloads and a vector that is easy to modify for rapid toolkit expansion. In the present report we employed ConVERGD to characterize an unexplored subpopulation of norepinephrine (NE)-producing neurons within the rodent locus coeruleus that co-express the endogenous opioid gene prodynorphin (Pdyn). These studies showcase ConVERGD as a versatile tool for targeting diverse cell types and reveal Pdyn-expressing NE+ locus coeruleus neurons as a small neuronal subpopulation capable of driving anxiogenic behavioral responses in rodents.

Estrogen promotes gonadotropin-releasing hormone expression by regulating tachykinin 3 and prodynorphin systems in chicken.

The "KNDy neurons" located in the hypothalamic arcuate nucleus (ARC) of mammals are known to co-express kisspeptin, neurokinin B (NKB), and dynorphin (DYN), and have been identified as key mediators of the feedback regulation of steroid hormones on gonadotropin-releasing hormone (GnRH). However, in birds, the genes encoding kisspeptin and its receptor GPR54 are genomic lost, leaving unclear mechanisms for feedback regulation of GnRH by steroid hormones. Here, the genes tachykinin 3 (TAC3) and prodynorphin (PDYN) encoding chicken NKB and DYN neuropeptides were successfully cloned. Temporal expression profiling indicated that TAC3, PDYN and their receptor genes (TACR3, OPRK1) were mainly expressed in the hypothalamus, with significantly higher expression at 30W than at 15W. Furthermore, overexpression or interference of TAC3 and PDYN can regulate the GnRH mRNA expression. In addition, in vivo and in vitro assays showed that estrogen (E2) could promote the mRNA expression of TAC3, PDYN, and GnRH, as well as the secretion of GnRH/LH. Mechanistically, E2 could dimerize the nuclear estrogen receptor 1 (ESR1) to regulate the expression of TAC3 and PDYN, which promoted the mRNA and protein expression of GnRH gene as well as the secretion of GnRH. In conclusion, these results revealed that E2 could regulate the GnRH expression through TAC3 and PDYN systems, providing novel insights for reproductive regulation in chickens.

Pre-proenkephalin 1 is Downregulated Under Unloading and is Involved in Osteoblast Biology.

Pre-proenkephalin 1 (Penk1) is a pro-neuropeptide that belongs to the typical opioid peptide's family, having analgesic properties. We previously found Penk1 to be the most downregulated gene in a whole gene profiling analysis performed in osteoblasts subjected to microgravity as a model of mechanical unloading. In this work, Penk1 downregulation was confirmed in the bones of two in vivo models of mechanical unloading: tail-suspended and botulinum toxin A (botox)-injected mice. Consistently, in the sera from healthy volunteers subjected to bed rest, we observed an inverse correlation between PENK1 and bed rest duration. These results prompted us to investigate a role for this factor in bone. Penk1 was highly expressed in mouse bone, but its global deletion failed to impact bone metabolism in vivo. Indeed, Penk1 knock out (Penk1-/-) mice did not show an overt bone phenotype compared to the WT littermates. Conversely, in vitro Penk1 gene expression progressively increased during osteoblast differentiation and its transient silencing in mature osteoblasts by siRNAs upregulated the transcription of the Sost1 gene encoding sclerostin, and decreased Wnt3a and Col1a1 mRNAs, suggesting an altered osteoblast activity due to an impairment of the Wnt pathway. In line with this, osteoblasts treated with the Penk1 encoded peptide, Met-enkephalin, showed an increase of Osx and Col1a1 mRNAs and enhanced nodule mineralization. Interestingly, primary osteoblasts isolated from Penk1-/- mice showed lower metabolic activity, ALP activity, and nodule mineralization, as well as a lower number of CFU-F compared to osteoblasts isolated from WT mice, suggesting that, unlike the transient inhibition, the chronic Penk1 deletion affects both osteoblast differentiation and activity. Taken together, these results highlight a role for Penk1 in the regulation of the response of the bone to mechanical unloading, potentially acting on osteoblast differentiation and activity in a cell-autonomous manner.

Proenkephalin deletion in hematopoietic cells induces intestinal barrier failure resulting in clinical feature similarities with irritable bowel syndrome in mice.

Opioid-dependent immune-mediated analgesic effects have been broadly reported upon inflammation. In preclinical mouse models of intestinal inflammatory diseases, the local release of enkephalins (endogenous opioids) by colitogenic T lymphocytes alleviate inflammation-induced pain by down-modulating gut-innervating nociceptor activation in periphery. In this study, we wondered whether this immune cell-derived enkephalin-mediated regulation of the nociceptor activity also operates under steady state conditions. Here, we show that chimeric mice engrafted with enkephalin-deficient bone marrow cells exhibit not only visceral hypersensitivity but also an increase in both epithelial paracellular and transcellular permeability, an alteration of the microbial topography resulting in increased bacteria-epithelium interactions and a higher frequency of IgA-producing plasma cells in Peyer's patches. All these alterations of the intestinal homeostasis are associated with an anxiety-like behavior despite the absence of an overt inflammation as observed in patients with irritable bowel syndrome. Thus, our results show that immune cell-derived enkephalins play a pivotal role in maintaining gut homeostasis and normal behavior in mice. Because a defect in the mucosal opioid system remarkably mimics some major clinical symptoms of the irritable bowel syndrome, its identification might help to stratify subgroups of patients.

Lateral hypothalamic proenkephalin neurons drive threat-induced overeating associated with a negative emotional state.

Psychological stressors, like the nearby presence of a predator, can be strong enough to induce physiological/hormonal alterations, leading to appetite changes. However, little is known about how threats can alter feeding-related hypothalamic circuit functions. Here, we found that proenkephalin (Penk)-expressing lateral hypothalamic (LHPenk) neurons of mice exposed to predator scent stimulus (PSS) show sensitized responses to high-fat diet (HFD) eating, whereas silencing of the same neurons normalizes PSS-induced HFD overconsumption associated with a negative emotional state. Downregulation of endogenous enkephalin peptides in the LH is crucial for inhibiting the neuronal and behavioral changes developed after PSS exposure. Furthermore, elevated corticosterone after PSS contributes to enhance the reactivity of glucocorticoid receptor (GR)-containing LHPenk neurons to HFD, whereas pharmacological inhibition of GR in the LH suppresses PSS-induced maladaptive behavioral responses. We have thus identified the LHPenk neurons as a critical component in the threat-induced neuronal adaptation that leads to emotional overconsumption.

Endogenous opioid system modulates conditioned cocaine reward in a sex-dependent manner.

Cocaine predictive cues and contexts exert powerful control over behaviour and can incite cocaine seeking and taking. This type of conditioned behaviour is encoded within striatal circuits, and these circuits and behaviours are, in part, regulated by opioid peptides and receptors expressed in striatal medium spiny neurons. We previously showed that augmenting levels of the opioid peptide enkephalin in the striatum facilitates acquisition of cocaine conditioned place preference (CPP), while opioid receptor antagonists attenuate expression of cocaine CPP. However, whether striatal enkephalin is necessary for acquisition of cocaine CPP and maintenance during extinction remains unknown. To address this, we generated mice with a targeted deletion of enkephalin from dopamine D2-receptor expressing medium spiny neurons and tested them in a cocaine CPP paradigm. Low striatal enkephalin levels did not attenuate acquisition of CPP. However, expression of preference, assessed after acute administration of the opioid receptor antagonist naloxone, was blocked in females, regardless of genotype. When saline was paired with the cocaine context during extinction sessions, females, regardless of genotype, extinguished preference faster than males, and this was prevented by naloxone when paired with the cocaine context. We conclude that while striatal enkephalin is not necessary for acquisition, expression, or extinction of cocaine CPP, expression and extinction of cocaine preference in females is mediated by an opioid peptide other than striatal enkephalin. The unique sensitivity of females to opioid antagonists suggests sex should be a consideration when using these compounds in the treatment of cocaine use disorder.

Enkephalin-δ Opioid Receptor Signaling Mediates Glucoprivic Suppression of LH Pulse and Gluconeogenesis in Female Rats.

Energy availability is an important regulator of reproductive function at various reproductive phases in mammals. Glucoprivation induced by 2-deoxy-D-glucose (2DG), an inhibitor of glucose utilization, as an experimental model of malnutrition suppresses the pulsatile release of GnRH/LH and induces gluconeogenesis. The present study was performed with the aim of examining whether enkephalin-δ-opioid receptor (DOR) signaling mediates the suppression of pulsatile GnRH/LH release and gluconeogenesis during malnutrition. The administration of naltrindole hydrochloride (NTI), a selective DOR antagonist, into the third ventricle blocked the suppression of LH pulses and part of gluconeogenesis induced by IV 2DG administration in ovariectomized rats treated with a negative feedback level of estradiol-17â€…ß (OVX + low E2). The IV 2DG administration significantly increased the number of Penk (enkephalin gene)-positive cells coexpressing fos (neuronal activation marker gene) in the paraventricular nucleus (PVN), but not in the arcuate nucleus (ARC) in OVX + low E2 rats. Furthermore, double in situ hybridization for Penk/Pdyn (dynorphin gene) in the PVN revealed that approximately 35% of the PVN Penk-expressing cells coexpressed Pdyn. Double in situ hybridization for Penk/Crh (corticotropin-releasing hormone gene) in the PVN and Penk/Kiss1 (kisspeptin gene) in the ARC revealed that few Penk-expressing cells coexpressed Crh and Kiss1. Taken together, these results suggest that central enkephalin-DOR signaling mediates the suppression of pulsatile LH release during malnutrition. Moreover, the current study suggests that central enkephalin-DOR signaling is also involved in gluconeogenesis during malnutrition in female rats.

Organisation of enkephalin inputs and outputs of the central nucleus of the amygdala in mice.

The central nucleus of the amygdala (CeA) is a key hub integrating sensory inputs and modulating behavioural outputs. The CeA is a complex structure with discrete subdivisions, high peptidergic heterogeneity and broad CNS afferent and efferent projections. While several neuropeptide systems within the CeA have been examined in detail, less is known about CeA preproenkephalin (ppENK) cells. Here, we used a recently developed transgenic Penk-Cre mouse line to advance our understanding of the efferent and afferent connectivity of ppENK in the CeA. First, to determine the fidelity of Cre expression in Penk-Cre transgenic mice, we conducted RNAscope in the CeA of Penk-Cre mice. Our analysis revealed that 96.6 % of CeA Cre+ neurons co-expressed pENK mRNA, and 99.7 % of CeA pENK+ neurons co-expressed Cre mRNA, indicating faithful recapitulation of Cre expression in CeA ppENK-expressing cells, supporting the fidelity of the Penk-Cre reporter mouse. Anterograde tracing of CeAPenk cells showed strong efferent projections to the extended amygdala, midbrain and hindbrain PBN and NTS. Retrograde tracing of Penk afferents to the CeA were more restricted, with primary innervation originating within the amygdala complex and bed nucleus of the stria terminalis, and minor innervation from the parabrachial nucleus and nucleus of the solitary tract. Together, our data provide a comprehensive map of ENKergic efferent and afferent connectivity of the CeA in Penk-Cre mice. Further, we highlight both the utility and limitations of the Penk-Cre mice to study the function of CeA, PBN and NTS ppENK cells.

Cellular Profiles of Prodynorphin and Preproenkephalin mRNA-Expressing Neurons in the Anterior Olfactory Tubercle of Mice.

The olfactory tubercle (OT) is a striatal region that receives olfactory inputs. mRNAs of prodynorphin (Pdyn) and preproenkephalin (Penk), precursors of dynorphins and enkephalins, respectively, are strongly expressed in the striatum. Both produce opioid peptides with various physiological effects such as pain relief and euphoria. Recent studies have revealed that OT has anatomical and cytoarchitectonic domains that play different roles in odor-induced motivated behavior. Neuronal subtypes of the OT can be distinguished by their expression of the dopamine receptors D1 (Drd1) and D2 (Drd2). Here, we addressed whether and which type of opioid peptide precursors the D1- and D2-expressing neurons in the OT express. We used multiple fluorescence in situ hybridization for mRNAs of the opioid precursors and dopamine receptors to characterize mouse OT neurons. Pdyn was mainly expressed by Drd1-expressing cells in the dense cell layer (DCL) of the OT, whereas Penk was expressed primarily by Drd2-expressing cells in the DCL. We also confirmed the presence of a larger population of Pdyn-Penk-Drd1 co-expressing cells in the DCL of the anteromedial OT compared with the anterolateral OT. These observations will help understand whether and how dynorphins and enkephalins in the OT are involved in diverse odor-induced motivated behaviors.

Prodynorphin (PDYN) gene polymorphisms in Turkish patients with methamphetamine use disorder, changes in PDYN serum levels in withdrawal and the relationship between PDYN, temperament and depression.

Aim of the study is to compare prodynorphin (PDYN) rs1997794, rs1022563, rs6045819, rs2235749 polymorphisms in individuals with methamphetamine use disorder (MD) to that of healthy controls (HC), and to investigate the differences in serum PDYN levels in methamphetamine withdrawal. It is also aimed to explore the temperament characteristics and depression and their relationship with PDYN polymorphisms and PDYN serum levels in MD group. PDYN gene and serum levels were studied in 134 patients with MD and 97 HC. Patients with MD were administered Beck Depression Inventory (BDI) and Temperament Evaluation of Memphis, Pisa, Paris and San Diego Autoquestionnaire (TEMPS-A). For rs1022563 polymorphism, TT and CT genotype frequency and T allele frequency were significantly higher in the MD group than the frequencies in HC. It was found that rs2235749 polymorphism AA genotype was associated with increased risk of MD. PDYN rs1997794 CT genotypes had significantly higher scores of TEMPS-A irritable than CC genotypes and PDYN rs1022563 CC genotypes had significantly higher scores of TEMPS-A irritable than TT genotypes. PDYN levels among persons with MD were significantly higher than among the HC group when the withdrawal level increased and withdrawal symptoms improved. During the period in which the withdrawal level increased, there was a negative correlation between PDYN level and BDI and a positive relationship between PDYN level and TEMPS-A hyperthymic. It may be beneficial to screen temperament characteristics associated with increased risk of addiction in patients with MD and develop interventions based on temperament characteristics and the effects of PDYN.

The Expression Pattern of Genes Related to Melanogenesis and Endogenous Opioids in Psoriasis.

The melanocortin system is a major regulator of stress responses in the skin and is responsible for the induction of melanin synthesis through activation of melanogenesis enzymes. The expression of both melanocortin system genes and melanogenesis enzyme genes is altered in psoriasis, and the focus here was on twelve genes related to the signal transduction between them. Additionally, five endogenous opioid system genes that are involved in cutaneous inflammation were examined. Quantitative real-time-PCR was utilized to measure mRNA expression in punch biopsies from lesional and non-lesional skin of psoriasis patients and from the skin of healthy control subjects. Most of the genes related to melanogenesis were down-regulated in patients (CREB1, MITF, LEF1, USF1, MAPK14, ICAM1, PIK3CB, RPS6KB1, KIT, and ATRN). Conversely, an up-regulation occurred in the case of opioids (PENK, PDYN, and PNOC). The suppression of genes related to melanogenesis is in agreement with the reported reduction in pigmentation signaling in psoriatic skin and potentially results from the pro-inflammatory environment. The increase in endogenous opioids can be associated with their involvement in inflammatory dysregulation in psoriasis.

Refeeding activates neurons in the dorsomedial hypothalamus to inhibit food intake and promote positive valence.

OBJECTIVE: The regulation of food intake is a major research area in the study of obesity, which plays a key role in the development of metabolic syndrome. Gene targeting studies have clarified the roles of hypothalamic neurons in feeding behavior, but the deletion of a gene has a long-term effect on neurophysiology. Our understanding of short-term changes such as appetite under physiological conditions is therefore still limited. METHODS: Targeted recombination in active populations (TRAP) is a newly developed method for labeling active neurons by using tamoxifen-inducible Cre recombination controlled by the promoter of activity-regulated cytoskeleton-associated protein (Arc/Arg3.1), a member of immediate early genes. Transgenic mice for TRAP were fasted overnight, re-fed with normal diet, and injected with 4-hydroxytamoxifen 1 h after the refeeding to label the active neurons. The role of labeled neurons was examined by expressing excitatory or inhibitory designer receptors exclusively activated by designer drugs (DREADDs). The labeled neurons were extracted and RNA sequencing was performed to identify genes that are specifically expressed in these neurons. RESULTS: Fasting-refeeding activated and labeled neurons in the compact part of the dorsomedial hypothalamus (DMH) that project to the paraventricular hypothalamic nucleus. Chemogenetic activation of the labeled DMH neurons decreased food intake and developed place preference, an indicator of positive valence. Chemogenetic activation or inhibition of these neurons had no influence on the whole-body glucose metabolism. The labeled DMH neurons expressed prodynorphin (pdyn), gastrin-releasing peptide (GRP), cholecystokinin (CCK), and thyrotropin-releasing hormone receptor (Trhr) genes. CONCLUSIONS: We identified a novel cell type of DMH neurons that can inhibit food intake and promote feeding-induced positive valence. Our study provides insight into the role of DMH and its molecular mechanism in the regulation of appetite and emotion.

Epigenetic and Transcriptional Control of the Opioid Prodynorphine Gene: In-Depth Analysis in the Human Brain.

Neuropeptides serve as neurohormones and local paracrine regulators that control neural networks regulating behavior, endocrine system and sensorimotor functions. Their expression is characterized by exceptionally restricted profiles. Circuit-specific and adaptive expression of neuropeptide genes may be defined by transcriptional and epigenetic mechanisms controlled by cell type and subtype sequence-specific transcription factors, insulators and silencers. The opioid peptide dynorphins play a critical role in neurological and psychiatric disorders, pain processing and stress, while their mutations cause profound neurodegeneration in the human brain. In this review, we focus on the prodynorphin gene as a model for the in-depth epigenetic and transcriptional analysis of expression of the neuropeptide genes. Prodynorphin studies may provide a framework for analysis of mechanisms relevant for regulation of neuropeptide genes in normal and pathological human brain.

miR-506-loaded gelatin nanospheres target PENK and inactivate the ERK/Fos signaling pathway to suppress triple-negative breast cancer aggressiveness.

Triple-negative breast cancer (TNBC) is the most malignant subtype of breast cancer. Some microRNAs (miRNAs) were abnormally expressed in TNBC, and they are closely related to the occurrence and progression of TNBC. Here, we found that miR-506 was significantly downregulated in TNBC and relatively lower miR-506 expression predicted a poorer prognosis. Moreover, we found that miR-506 could inhibit MDA-MB-231 cell viability, colony formation, migration, and invasion, and suppress the ERK/Fos oncogenic signaling pathway through upregulating its direct target protein proenkephalin (PENK). Therefore, miR-506 was proposed as a nucleic acid drug for TNBC therapy. However, miRNA is unstable in vivo, which limiting its application as a therapeutic drug via conventional oral or injected therapies. Here, a gelatin nanosphere (GN) delivery system was applied for the first time to load exogenous miRNA. Exogenous miR-506 mimic was loaded on GNs and injected into the in situ TNBC animal model, and the miR-506 could achieve sustained and controlled release. The results confirmed that overexpression of miR-506 and PENK in vivo through loading on GNs inhibited in situ triple-negative breast tumor growth and metastasis significantly in the xenograft model. Moreover, we indicated that the ERK/Fos signaling pathway was intensively inactivated after overexpression of miR-506 and PENK both in vitro and in vivo, which was further validated by the ERK1/2-specific inhibitor SCH772984. In conclusion, this study demonstrates that miR-506-loaded GNs have great potential in anti-TNBC aggressiveness therapy.

Parabrachial opioidergic projections to preoptic hypothalamus mediate behavioral and physiological thermal defenses.

Maintaining stable body temperature through environmental thermal stressors requires detection of temperature changes, relay of information, and coordination of physiological and behavioral responses. Studies have implicated areas in the preoptic area of the hypothalamus (POA) and the parabrachial nucleus (PBN) as nodes in the thermosensory neural circuitry and indicate that the opioid system within the POA is vital in regulating body temperature. In the present study we identify neurons projecting to the POA from PBN expressing the opioid peptides dynorphin and enkephalin. Using mouse models, we determine that warm-activated PBN neuronal populations overlap with both prodynorphin (Pdyn) and proenkephalin (Penk) expressing PBN populations. Here we report that in the PBN Prodynorphin (Pdyn) and Proenkephalin (Penk) mRNA expressing neurons are partially overlapping subsets of a glutamatergic population expressing Solute carrier family 17 (Slc17a6) (VGLUT2). Using optogenetic approaches we selectively activate projections in the POA from PBN Pdyn, Penk, and VGLUT2 expressing neurons. Our findings demonstrate that Pdyn, Penk, and VGLUT2 expressing PBN neurons are critical for physiological and behavioral heat defense.