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Zhu X, Li K, Gao Y. Adeno-associated virus-mediated in vivo suppression of expression of EPHX2 gene modulates the activity of paraventricular nucleus neurons in spontaneously hypertensive rats. Biochem Biophys Res Commun 2022; 606:121-127. [PMID: 35344709 DOI: 10.1016/j.bbrc.2022.03.084] [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: 03/13/2022] [Accepted: 03/16/2022] [Indexed: 11/29/2022]
Abstract
BACKGROUND Hypertension can be attributed to increased sympathetic activities. Presympathetic neurons in the paraventricular nucleus (PVN) of the hypothalamus are capable of modulating sympathetic outflow, thus contributing to the pathogenesis of neurogenic hypertension. Epoxyeicosatrienoic acids (EETs) were reported to have anti-hypertensive effects, which could be degraded by soluble epoxide hydrolase (sEH), encoded by EPHX2. However, the potential effect of EETs on PVN neuron activity and the underlying molecular mechanism are largely unknown. METHODS Knockdown of EPHX2 in spontaneously hypertensive rats (SHRs) was achieved by tail-intravenous injection of AAV plasmid containing shRNA targeting EPHX2. Whole-cell patch clamp was used to record action potentials of PVN neurons. An LC-MS/MS System was employed to determine 14,15-EET levels in rat cerebrospinal fluid. qPCR and western blotting were applied to examine the expression level of EPHX2 in various tissues. ELISA and immunofluorescence staining were applied to examine the levels of ATP, D-serine and glial fibrillary acidic protein (GFAP) in isolated astrocytes. RESULTS The expression level of EPHX2 was higher, while the level of 14,15-EET was lower in SHRs than normotensive Wistar-Kyoto rats (WKY) rats. The spike firing frequency of PNV neurons in SHRs was higher than in WKY rats at a given stimulus current, which could be reduced by either EPHX2 downregulation or 14,15-EET administration. In isolated hypothalamic astrocytes, the elevated intracellular ATP or D-serine induced by Angiotensin II (Ang II) treatment could be rescued by 14,15-EET addition or 14,15-EET combing serine racemase (SR) downregulation by siRNA, respectively. Furthermore, 14,15-EET treatment reduced the Ang II-induced elevation of GFAP immunofluorescence. CONCLUSIONS The elevation of EET levels by EPHX2 downregulation reduced presympathetic neuronal activity in the PVN of SHRs, leading to a reduced sympathetic outflow in hypertension rats. The ATP/SR/D-serine pathway of astrocytes is involved in EET-mediated neuroprotection.
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Affiliation(s)
- Xiaoming Zhu
- Heart Center and Beijing Key Laboratory of Hypertension, Beijing Chaoyang Hospital, Capital Medical University, Beijing, China.
| | - Kuibao Li
- Heart Center and Beijing Key Laboratory of Hypertension, Beijing Chaoyang Hospital, Capital Medical University, Beijing, China.
| | - Yuanfeng Gao
- Heart Center and Beijing Key Laboratory of Hypertension, Beijing Chaoyang Hospital, Capital Medical University, Beijing, China.
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2
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Social touch promotes interfemale communication via activation of parvocellular oxytocin neurons. Nat Neurosci 2020; 23:1125-1137. [PMID: 32719563 DOI: 10.1038/s41593-020-0674-y] [Citation(s) in RCA: 133] [Impact Index Per Article: 33.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Accepted: 06/18/2020] [Indexed: 12/19/2022]
Abstract
Oxytocin (OT) is a great facilitator of social life but, although its effects on socially relevant brain regions have been extensively studied, OT neuron activity during actual social interactions remains unexplored. Most OT neurons are magnocellular neurons, which simultaneously project to the pituitary and forebrain regions involved in social behaviors. In the present study, we show that a much smaller population of OT neurons, parvocellular neurons that do not project to the pituitary but synapse onto magnocellular neurons, is preferentially activated by somatosensory stimuli. This activation is transmitted to the larger population of magnocellular neurons, which consequently show coordinated increases in their activity during social interactions between virgin female rats. Selectively activating these parvocellular neurons promotes social motivation, whereas inhibiting them reduces social interactions. Thus, parvocellular OT neurons receive particular inputs to control social behavior by coordinating the responses of the much larger population of magnocellular OT neurons.
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Pati D, Harden SW, Sheng W, Kelly KB, de Kloet AD, Krause EG, Frazier CJ. Endogenous oxytocin inhibits hypothalamic corticotrophin-releasing hormone neurones following acute hypernatraemia. J Neuroendocrinol 2020; 32:e12839. [PMID: 32133707 PMCID: PMC7384450 DOI: 10.1111/jne.12839] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Revised: 01/24/2020] [Accepted: 02/06/2020] [Indexed: 12/12/2022]
Abstract
Significant prior evidence indicates that centrally acting oxytocin robustly modulates stress responsiveness and anxiety-like behaviour, although the neural mechanisms behind these effects are not entirely understood. A plausible neural basis for oxytocin-mediated stress reduction is via inhibition of corticotrophin-releasing hormone (CRH) neurones in the paraventricular nucleus of the hypothalamus (PVN) that regulate activation of the hypothalamic-pituitary-adrenal axis. Previously, we have shown that, following s.c. injection of 2.0 mol L-1 NaCl, oxytocin synthesising neurones are activated in the rat PVN, an oxytocin receptor (Oxtr)-dependent inhibitory tone develops on a subset of parvocellular neurones and stress-mediated increases in plasma corticosterone levels are blunted. In the present study, we utilised transgenic male CRH-reporter mice to selectively target PVN CRH neurones for whole-cell recordings. These experiments reveal that acute salt loading produces tonic inhibition of PVN CRH neurones through a mechanism that is largely independent of synaptic activity. Further studies reveal that a subset of CRH neurones within the PVN synthesise mRNA for Oxtr(s). Salt induced Oxtr-dependent inhibitory tone was eliminated in individual PVN CRH neurones filled with GDP-β-S. Additional electrophysiological studies suggest that reduced excitability of PVN CRH neurones in salt-loaded animals is associated with increased activation of inwardly rectifying potassium channels. Nevertheless, substantial effort to recapitulate the core effects of salt loading by activating Oxtr(s) with an exogenous agonist produced mixed results. Collectively, these results enhance our understanding of how oxytocin receptor-mediated signalling modulates the function of CRH neurones in the PVN.
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Affiliation(s)
- Dipanwita Pati
- Department of Pharmacodynamics, College of Pharmacy,
University of Florida
| | - Scott W. Harden
- Department of Pharmacodynamics, College of Pharmacy,
University of Florida
| | | | - Kyle B. Kelly
- Department of Pharmacodynamics, College of Pharmacy,
University of Florida
| | - Annette D. de Kloet
- Department of Physiology and Functional Genomics, College
of Medicine, University of Florida
| | - Eric G. Krause
- Department of Pharmacodynamics, College of Pharmacy,
University of Florida
| | - Charles J. Frazier
- Department of Pharmacodynamics, College of Pharmacy,
University of Florida
- Department of Neuroscience, College of Medicine, University
of Florida
- Corresponding author: Charles J.
Frazier, Ph.D., Associate Professor and University of Florida Term Professor,
Department of Pharmacodynamics, College of Pharmacy, University of Florida,
JHMHC Box 100487, Room P1-20, 1345 Center Drive, Gainesville, FL 32610, USA,
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Fischl MJ, Ueberfuhr MA, Drexl M, Pagella S, Sinclair JL, Alexandrova O, Deussing JM, Kopp-Scheinpflug C. Urocortin 3 signalling in the auditory brainstem aids recovery of hearing after reversible noise-induced threshold shift. J Physiol 2019; 597:4341-4355. [PMID: 31270820 PMCID: PMC6852351 DOI: 10.1113/jp278132] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Accepted: 07/03/2019] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Ongoing, moderate noise exposure does not instantly damage the auditory system but may cause lasting deficits, such as elevated thresholds and accelerated ageing of the auditory system. The neuromodulatory peptide urocortin-3 (UCN3) is involved in the body's recovery from a stress response, and is also expressed in the cochlea and the auditory brainstem. Lack of UCN3 facilitates age-induced hearing loss and causes permanently elevated auditory thresholds following a single 2 h noise exposure at moderate intensities. Outer hair cell function in mice lacking UCN3 is unaffected, so that the observed auditory deficits are most likely due to inner hair cell function or central mechanisms. Highly specific, rather than ubiquitous, expression of UCN3 in the brain renders it a promising candidate for designing drugs to ameliorate stress-related auditory deficits, including recovery from acoustic trauma. ABSTRACT Environmental acoustic noise is omnipresent in our modern society, with sound levels that are considered non-damaging still causing long-lasting or permanent changes in the auditory system. The small neuromodulatory peptide urocortin-3 (UCN3) is the endogenous ligand for corticotropin-releasing factor receptor type 2 and together they are known to play an important role in stress recovery. UCN3 expression has been observed in the auditory brainstem, but its role remains unclear. Here we describe the detailed distribution of UCN3 expression in the murine auditory brainstem and provide evidence that UCN3 is expressed in the synaptic region of inner hair cells in the cochlea. We also show that mice with deficient UCN3 signalling experience premature ageing of the auditory system starting at an age of 4.7 months with significantly elevated thresholds of auditory brainstem responses (ABRs) compared to age-matched wild-type mice. Following a single, 2 h exposure to moderate (84 or 94 dB SPL) noise, UCN3-deficient mice exhibited significantly larger shifts in ABR thresholds combined with maladaptive recovery. In wild-type mice, the same noise exposure did not cause lasting changes to auditory thresholds. The presence of UCN3-expressing neurons throughout the auditory brainstem and the predisposition to hearing loss caused by preventing its normal expression suggests UCN3 as an important neuromodulatory peptide in the auditory system's response to loud sounds.
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Affiliation(s)
- Matthew J Fischl
- Department of Biology II, Division Neurobiology, Ludwig-Maximilians-University, Munich, Germany
| | - Margarete A Ueberfuhr
- German Center for Vertigo and Balance Disorders, University Hospital Munich, Ludwig-Maximilians-University, Munich, Germany.,Graduate School of Systemic Neurosciences, Ludwig-Maximilians-University, Munich, Germany
| | - Markus Drexl
- German Center for Vertigo and Balance Disorders, University Hospital Munich, Ludwig-Maximilians-University, Munich, Germany
| | - Sara Pagella
- Department of Biology II, Division Neurobiology, Ludwig-Maximilians-University, Munich, Germany.,Graduate School of Systemic Neurosciences, Ludwig-Maximilians-University, Munich, Germany
| | - James L Sinclair
- Department of Biology II, Division Neurobiology, Ludwig-Maximilians-University, Munich, Germany
| | - Olga Alexandrova
- Department of Biology II, Division Neurobiology, Ludwig-Maximilians-University, Munich, Germany
| | - Jan M Deussing
- Max Planck Institute of Psychiatry, Molecular Neurogenetics, Munich, Germany
| | - Conny Kopp-Scheinpflug
- Department of Biology II, Division Neurobiology, Ludwig-Maximilians-University, Munich, Germany
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Zhang BB, Jin H, Bing YH, Zhang XY, Chu CP, Li YZ, Qiu DL. A Nitric Oxide-Dependent Presynaptic LTP at Glutamatergic Synapses of the PVN Magnocellular Neurosecretory Cells in vitro in Rats. Front Cell Neurosci 2019; 13:283. [PMID: 31316353 PMCID: PMC6610542 DOI: 10.3389/fncel.2019.00283] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Accepted: 06/11/2019] [Indexed: 11/13/2022] Open
Abstract
The magnocellular neurosecretory cells (MNCs) of the hypothalamic paraventricular nucleus (PVN) integrate incoming signals to secrete oxytocin (OT), and vasopressin (VP) from their nerve terminals in the posterior pituitary gland. In the absence of gamma-aminobutyric acid A (GABAA) and cannabinoids 1 (CB1) receptor activity, we used whole-cell patch-clamp recording, single-cell reverse transcription-multiplex polymerase chain reaction (SC-RT-mPCR), biocytin histochemistry and pharmacological methods to examine the mechanism of high frequency stimulus (HFS, 100 Hz)-induced long-term potentiation (LTP) at glutamatergic synapses in the PVN MNCs of juvenile male rats. Our results showed that HFS-induced LTP at glutamatergic synapses was accompanied by a decrease in the paired-pulse ratio (PPR) of the PVN MNCs. In these MNCs, HFS-induced LTP persisted in the presence of a group 1 metabotropic glutamate receptor (mGluR1) antagonist; however, it was abolished by an N-methyl-D-aspartic acid (NMDA) receptor blocker. Notably, HFS-induced LTP in the PVN MNCs was completely prevented by a nitric oxide synthase (NOS) inhibitor. The application of an NO donor not only induced the LTP of excitatory glutamatergic inputs in the PVN MNCs, but also occluded the HFS-induced LTP in these MNCs. Moreover, HFS-induced LTP in the PVN MNCs was also abolished by a specific protein kinase A (PKA) inhibitor, KT5720. SC-RT-mPCR analysis revealed that 64.5% (62/96) of MNCs expressed OT mRNA. Our results indicate that a HFS can induce an NMDA receptor and NO cascades dependent on presynaptic glutamatergic LTP in the PVN MNCs via a PKA signaling pathway.
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Affiliation(s)
- Bin-Bin Zhang
- Key Laboratory of Cellular Function and Pharmacology of Jilin Province, Yanbian University, Yanji, China.,Department of Physiology and Pathophysiology, College of Medicine, Yanbian University, Yanji, China
| | - Hua Jin
- Key Laboratory of Cellular Function and Pharmacology of Jilin Province, Yanbian University, Yanji, China.,Department of Nephrology, Affiliated Hospital of Yanbian University, Yanji, China
| | - Yan-Hua Bing
- Key Laboratory of Cellular Function and Pharmacology of Jilin Province, Yanbian University, Yanji, China.,Department of Physiology and Pathophysiology, College of Medicine, Yanbian University, Yanji, China
| | - Xin-Yuan Zhang
- Department of Physiology and Pathophysiology, College of Medicine, Yanbian University, Yanji, China
| | - Chun-Ping Chu
- Key Laboratory of Cellular Function and Pharmacology of Jilin Province, Yanbian University, Yanji, China
| | - Yu-Zi Li
- Key Laboratory of Cellular Function and Pharmacology of Jilin Province, Yanbian University, Yanji, China.,Department of Cardiology, Affiliated Hospital of Yanbian University, Yanji, China
| | - De-Lai Qiu
- Key Laboratory of Cellular Function and Pharmacology of Jilin Province, Yanbian University, Yanji, China.,Department of Physiology and Pathophysiology, College of Medicine, Yanbian University, Yanji, China
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Martinon D, Dabrowska J. Corticotropin-Releasing Factor Receptors Modulate Oxytocin Release in the Dorsolateral Bed Nucleus of the Stria Terminalis (BNST) in Male Rats. Front Neurosci 2018; 12:183. [PMID: 29618970 PMCID: PMC5871712 DOI: 10.3389/fnins.2018.00183] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Accepted: 03/06/2018] [Indexed: 11/13/2022] Open
Abstract
The neuropeptide oxytocin (OT) plays an important role in the regulation of social and anxiety-like behavior. Our previous studies have shown that OT neurons send projections from the hypothalamus to the dorsolateral bed nucleus of the stria terminalis (BNSTdl), a forebrain region critically involved in the modulation of anxiety-like behavior. Importantly, these OT terminals in the BNSTdl express presynaptic corticotropin releasing factor (CRF) receptor type 2 (CRFR2). This suggests that CRFR2 might be involved in the modulation of OT release. To test this hypothesis, we measured OT content in microdialysates collected from the BNSTdl of freely-moving male Sprague-Dawley rats following the administration of a selective CRFR2 agonist (Urocortin 3) or antagonist (Astressin 2B, As2B). To determine if type 1 CRF receptors (CRFR1) are also involved, we used selective CRFR1 antagonist (NBI35965) as well as CRF, a putative ligand of both CRFR1 and CRFR2. All compounds were delivered directly into the BNSTdl via reverse dialysis. OT content in the microdialysates was measured with highly sensitive and selective radioimmunoassay. Blocking CRFR2 with As2B caused an increase in OT content in BNSTdl microdialysates, whereas CRFR2 activation by Urocortin 3 did not have an effect. The As2B-induced increase in OT release was blocked by application of the CRFR1 antagonist demonstrating that the effect was dependent on CRFR1 transmission. Interestingly, CRF alone caused a delayed increase in OT content in BNSTdl microdialysates, which was dependent on CRF2 but not CRF1 receptors. Our results suggest that members of the CRF peptide family modulate OT release in the BNSTdl via a fine-tuned mechanism that involves both CRFR1 and CRFR2. Further exploration of mechanisms by which endogenous OT system is modulated by CRF peptide family is needed to better understand the role of these neuropeptides in the regulation of anxiety and the stress response.
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Affiliation(s)
- Daisy Martinon
- Department of Cellular and Molecular Pharmacology, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, IL, United States
| | - Joanna Dabrowska
- Department of Cellular and Molecular Pharmacology, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, IL, United States.,Department of Neuroscience, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, IL, United States
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Corticotropin releasing factor excites neurons of posterior hypothalamic nucleus to produce tachycardia in rats. Sci Rep 2016; 6:20206. [PMID: 26831220 PMCID: PMC4735335 DOI: 10.1038/srep20206] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Accepted: 12/23/2015] [Indexed: 12/26/2022] Open
Abstract
Corticotropin releasing factor (CRF), a peptide hormone involved in the stress response, holds a key position in cardiovascular regulation. Here, we report that the central effect of CRF on cardiovascular activities is mediated by the posterior hypothalamic nucleus (PH), an important structure responsible for stress-induced cardiovascular changes. Our present results demonstrate that CRF directly excites PH neurons via two CRF receptors, CRFR1 and CRFR2, and consequently increases heart rate (HR) rather than the mean arterial pressure (MAP) and renal sympathetic nerve activity (RSNA). Bilateral vagotomy does not influence the tachycardia response to microinjection of CRF into the PH, while β adrenergic receptor antagonist propranolol almost totally abolishes the tachycardia. Furthermore, microinjecting CRF into the PH primarily increases neuronal activity of the rostral ventrolateral medulla (RVLM) and rostral ventromedial medulla (RVMM), but does not influence that of the dorsal motor nucleus of the vagus nerve (DMNV). These findings suggest that the PH is a critical target for central CRF system in regulation of cardiac activity and the PH-RVLM/RVMM-cardiac sympathetic nerve pathways, rather than PH-DMNV-vagus pathway, may contribute to the CRF-induced tachycardia.
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Oxytocin in the nucleus accumbens shell reverses CRFR2-evoked passive stress-coping after partner loss in monogamous male prairie voles. Psychoneuroendocrinology 2016; 64:66-78. [PMID: 26615473 PMCID: PMC4698175 DOI: 10.1016/j.psyneuen.2015.11.011] [Citation(s) in RCA: 101] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Revised: 10/12/2015] [Accepted: 11/12/2015] [Indexed: 12/21/2022]
Abstract
Loss of a partner can have severe effects on mental health. Here we explore the neural mechanisms underlying increased passive stress-coping, indicative of depressive-like behavior, following the loss of the female partner in the monogamous male prairie vole. We demonstrate that corticotropin-releasing factor receptor 2 (CRFR2) in the nucleus accumbens shell mediates social loss-induced passive coping. Further, we show that partner loss compromises the oxytocin system through multiple mechanisms. Finally, we provide evidence for an interaction of the CRFR2 and oxytocin systems in mediating the emotional consequences of partner loss. Our results suggest that chronic activation of CRFR2 and suppression of striatal oxytocin signaling following partner loss result in an aversive emotional state that may share underlying mechanisms with bereavement. We propose that the suppression of oxytocin signaling is likely adaptive during short separations to encourage reunion with the partner and may have evolved to maintain long-term partnerships. Additionally, therapeutic strategies targeting these systems should be considered for treatment of social loss-mediated depression.
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