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Zhang J, Zhou H, Li P, Shi H, Sui X, Wang Y, Shi J, Wang L. Hypothalamic response with PKA/CREB signaling is associated with direct cerebroventricular administration of bombesin-induced scratching. Brain Res 2022; 1789:147950. [PMID: 35618015 DOI: 10.1016/j.brainres.2022.147950] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2021] [Revised: 04/29/2022] [Accepted: 05/19/2022] [Indexed: 11/28/2022]
Abstract
Bombesin (BN) is an itch-specific mediator that causes intense itch-scratching activity in mammals. Although most examinations of BN-induced itch processing have focused on the spinal cord, the involvement of central nervous system mechanisms remains unclear. Here, we investigated how relationships among hypothalamic regions regulate BN-mediated itch-scratch processes. We found that intracerebroventricular (i.c.v.) administration of BN (0.04-4 μg) elicited intense itch scratching in mice, whereas BN (0.4-400 μg) administered via intravenous tail injection failed to evoke a scratching response. Additionally, nalfurafine had no significant effects on BN-induced scratching behavior, indicating that central modulation of BN is distinct from histamine-mediated histaminergic itch and chloroquine-mediated non-histaminergic itch signaling pathways. We labeled BN with a fluorescent tag, 7-nitrobenz-2-oxa-1 (NBD), and traced its fluorescence in the hypothalamus for 30 min following i.c.v. NBD-BN administration. Accordingly, we confirmed that i.c.v. administration of BN enhanced c-Fos expression in the dorsal medial nucleus of the hypothalamus, where neuromedin B receptors and gastrin-releasing peptide receptors are highly expressed. Interestingly, in situ injection of BN into the hypothalamus immediately and robustly induced itch-scratching behavior. Moreover, gene transcripts and western blot assay revealed that BN receptor-dependent PKA/CREB signaling was upregulated in the hypothalamus after i.c.v. administration of BN. Consistently, pretreatment with a PKA inhibitor, Rp-cAMP, significantly reduced BN-induced scratching behavior. Our results indicate that the dorsal medial nucleus of the hypothalamus may be a key nucleus in mediating BN-mediated itch and hypothalamic PKA/CREB signaling is involved in regulating BN-mediated itch.
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Affiliation(s)
- Jingxin Zhang
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China; The Key Laboratory of Basic Pharmacology of the Educational Minister, Zunyi Medical University, Zunyi, Guizhou 563000, China.
| | - Hu Zhou
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China.
| | - Pengfei Li
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China.
| | - Huaxiang Shi
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China.
| | - Xin Sui
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China.
| | - Yongan Wang
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China.
| | - Jingshan Shi
- The Key Laboratory of Basic Pharmacology of the Educational Minister, Zunyi Medical University, Zunyi, Guizhou 563000, China.
| | - Liyun Wang
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China.
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Chen YL, He ZG, Wang Q, Xiang HB, Fan L, Xiong J. Specific Patterns of Spinal Metabolite Ratio Underlying α-Me-5-HT-evoked Pruritus Compared with Compound 48/80 Based on Proton Nuclear Magnetic Resonance Spectroscopy. Curr Med Sci 2020; 40:761-766. [PMID: 32862388 DOI: 10.1007/s11596-020-2233-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 06/12/2020] [Indexed: 01/03/2023]
Abstract
Mechanisms of pruritus are implicated in the dysregulation of the metabolites in the spinal cord. We investigated pruritus behavioral testing in three groups of young adult male C57Bl/6 mice, including one group treated with normal saline, while the other groups intradermally injected with α-Me-5-HT (histamine-independent pruritogen), compound 48/80 (histamine-dependent pruritogen) at the nape skin of the neck, respectively. Proton nuclear magnetic resonance spectroscopy (MRS) was used to compare spinal metabolites from the vertebral cervical among three groups, and to study the association of spinal metabolite ratio and pruritus intensity. The MRS-measured N-acetylaspartate-to-myoinositol ratio (NAA/Ins) was significantly correlated with the number of scratches between normal saline group and 48/80 group or α-Me-5-HT group (both P<0.0001), indicating that NAA/Ins may be a robust surrogate marker of histamine-independent/dependent pruritogen. There was significant difference in Glu/Ins between normal saline group and 48/80 group (P=0.017), indicating that Glu/Ins may be a surrogate marker of histamine-dependent pruritogen, while GABA/Ins was highly significantly different between normal saline group and α-Me-5-HT group (P=0.008), suggesting that GABA/Ins may be a surrogate marker of histamine-independent pruritogen. MRS may reflect the extent of pruritus intensity elicited by α-Me-5-HT and compound 48/80 with sensitivity similar to the number of scratches, and above potential markers need to be further validated in pre-clinical and clinical treatment trials.
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Affiliation(s)
- Ying-le Chen
- Department of Anesthesiology, the First Affiliated Quanzhou Hospital of Fujian Medical University, Quanzhou, 362000, China
| | - Zhi-Gang He
- Emergency Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Qian Wang
- Department of Anesthesiology and Pain Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Hong-Bing Xiang
- Department of Anesthesiology and Pain Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Li Fan
- Department of Orthopedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China.
| | - Jun Xiong
- Hepatobiliary Surgery Center, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China.
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Ajayi AAL. Itching, chloroquine, and malaria: a review of recent molecular and neuroscience advances and their contribution to mechanistic understanding and therapeutics of chronic non-histaminergic pruritus. Int J Dermatol 2018; 58:880-891. [PMID: 30362504 DOI: 10.1111/ijd.14252] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Revised: 08/23/2018] [Accepted: 08/31/2018] [Indexed: 12/20/2022]
Abstract
Chloroquine (CQ) is an antimalarial drug that elicits severe pruritus in black Africans with malaria fever. This acute itching (2-7 days duration) exhibits age dependency and a racial and genetic predilection. CQ itch is non-histaminergic, which makes it both a good model and a tool to probe the mechanisms of chronic itch. This review focuses on recently discovered mechanisms, neuroscience, mediators, and receptors that are implicated in molecular studies of CQ pruritus. CQ pruritus mechanisms are also compared to that of itching following other systemic diseases, such as chronic kidney disease, chronic liver disease, skin disorders, and burns. There are striking similarities between CQ itching pathways and other chronic itch secondary to systemic disease with or without skin lesions, which have not been previously highlighted. Prominent among these are the shared roles of skin, neural and spinal μ opiate receptors, kappa opiate receptor, nitric oxide, serotonin via 5HT1B/D receptors, cytokines, especially interleukins, and tumor necrosis factor. There is elaborate "cross talk" among the diverse mediators and receptors involved in CQ-induced pruritus. CQ also binds to the mas-related G protein coupled receptors MrgprA3/MrgprX1 present in a small proportion (4-5%) of dorsal root ganglion neurons and skin. The mrgprA3 CQ receptors are coupled to PLC-β3 and a chloride channel to initiate skin itch action potentials in C nerve fibers. Mrgpra3/X1 couples to TRPA1 for calcium influx into neuronal cells at noncutaneous sites. Central CQ itch occurs via gastrin-related peptide (GRP) and its receptor (GRPR) in the dorsal spinothalamic tracts, as well as glutamic mediated GRP projection to parabrachial nucleus. The possibility of chronic itch therapy based on personalized medicine, genetics, and transcriptomics or the use of itch "polypill/polycream" are discussed.
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Affiliation(s)
- Adesuyi A L Ajayi
- Department of Medicine, Division of Clinical Pharmacology, Baylor College of Medicine, Houston, TX, USA
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Ehling S, Butler A, Thi S, Ghashghaei HT, Bäumer W. To scratch an itch: Establishing a mouse model to determine active brain areas involved in acute histaminergic itch. IBRO Rep 2018; 5:67-73. [PMID: 30364768 PMCID: PMC6197726 DOI: 10.1016/j.ibror.2018.10.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Accepted: 10/13/2018] [Indexed: 12/30/2022] Open
Abstract
The specific histamine H4 receptor agonist ST-1006 induces acute itch in mice. Histaminergic itch increases neuronal activity in the medial habenula. Selective H4R activation in the skin increases neuronal activity in the medial habenula.
Background Strategies to efficiently control itch require a deep understanding of the underlying mechanisms. Several areas in the brain involved in itch and scratching responses have been postulated, but the central mechanisms that drive pruritic responses are still unknown. Histamine is recognized as a major mediator of itch in humans, and has been the most frequently used stimulus as an experimental pruritogen for brain imaging of itch. Objective Histaminergic itch via histamine and the selective histamine H4 receptor (H4R) agonist, ST-1006, recruit brain nuclei through c-fos activation and activate specific areas in the brain. Methods An acute itch model was established in c-fos-EGFP transgenic mice using ST-1006 and histamine. Coronal brain sections were stained for c-fos immunoreactivity and the forebrain was mapped for density of c-fos + nuclei. Results Histamine and ST-1006 significantly increased scratching response in c-fos-EGFP mice compared to vehicle controls. Mapping c-fos immunostained brain sections revealed neuronal activity in the cortex, striatum, hypothalamus, thalamus, amygdala, and the midbrain. Conclusions Histaminergic itch and selective H4R activation significantly increased the density of c-fos + nuclei in the medial habenula (MHb). Thus, the MHb may be a new target to investigate and subsequently develop novel mechanism-based strategies to treat itch and possibly provide a locus for pharmacological control of pruritus.
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Affiliation(s)
- Sarah Ehling
- Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, NC, USA.,Institute of Pharmacology and Toxicology, Faculty of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
| | - Ashley Butler
- Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, NC, USA
| | - Stephanie Thi
- Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, NC, USA
| | - H Troy Ghashghaei
- Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, NC, USA
| | - Wolfgang Bäumer
- Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, NC, USA.,Institute of Pharmacology and Toxicology, Faculty of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
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Chen M, Li ZX, Wang Q, Xiang HB. Altered Expression of Differential Genes in Thoracic Spinal Cord Involved in Experimental Cholestatic Itch Mouse Model. Curr Med Sci 2018; 38:679-683. [PMID: 30128878 DOI: 10.1007/s11596-018-1930-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Revised: 07/10/2018] [Indexed: 12/29/2022]
Abstract
The spinal origin of cholestatic itch in experimental obstructive jaundice mouse model remains poorly understood. In this study, the jaundice model was established by bile duct ligation (BDL) in mice, and differential gene expression patterns were analyzed in the lower thoracic spinal cord involved in cholestatic pruritus after BDL operation using high-throughput RNA sequencing. At 21st day after BDL, the expression levels of ENSRNOG00000060523, ENSRNOG00000058405 and ENSRNOG00000055193 mRNA were significantly up-regulated, and those of ENSRNOG00000042197, ENSRNOG00000008478, ENSRNOGOOOOOO19607, ENSRNOG00000020647, ENSRNOG00000046289, Gemin8, Serpina3n and Trim63 mRNA were significantly down-regulated in BDL group. The RNAseq data of selected mRNAs were validated by RT-qPCR. The expression levels of ENSRNOG00000042197, ENSRNOG00000008478, ENSRNOGOOOOOO 19607, ENSRNOG00000020647, ENSRNOG00000046289 and Serpina3n mRNA were significantly down-regulated in BDL group. This study suggested that cholestatic pruritus in experimental obstructive jaundice mouse model is related with in the changes of gene expression profiles in spinal cord.
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Affiliation(s)
- Ming Chen
- Department of Anesthesiology, Hubei Maternal and Child Health Hospital, Wuhan, 430060, China
| | - Zhi-Xiao Li
- Department of Anesthesiology and Pain Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Qian Wang
- Department of Anesthesiology and Pain Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Hong-Bing Xiang
- Department of Anesthesiology and Pain Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
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