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Segregation of calcium signalling mechanisms in magnocellular neurones and terminals. Cell Calcium 2012; 51:293-9. [DOI: 10.1016/j.ceca.2012.02.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Accepted: 02/03/2012] [Indexed: 11/22/2022]
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52
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Wacker DW, Ludwig M. Vasopressin, oxytocin, and social odor recognition. Horm Behav 2012; 61:259-65. [PMID: 21920364 DOI: 10.1016/j.yhbeh.2011.08.014] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2011] [Revised: 08/12/2011] [Accepted: 08/17/2011] [Indexed: 11/30/2022]
Abstract
Central vasopressin and oxytocin, and their homologues, modulate a multitude of social behaviors in a variety of animal taxa. All social behavior requires some level of social (re)cognition, and these neuropeptides exert powerful effects on an animal's ability to recognize and appropriately respond to a conspecific. Social cognition for many mammals, including rodents, begins at the main and accessory olfactory systems. We recently identified vasopressin expressing neurons in the main and accessory olfactory bulb and in the anterior olfactory nucleus, a region of olfactory cortex that transmits and processes information in the main olfactory system. We review this and other work demonstrating that both vasopressin and oxytocin modulate conspecific social recognition at the level of the olfactory system. We also outline recent work on the somato-dendritic release of vasopressin and oxytocin, and propose a model by which the somato-dendritic priming of these neuropeptides in main olfactory regions may facilitate the formation of short-term social odor memories. This article is part of a Special Issue entitled Oxytocin, Vasopressin, and Social Behavior.
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Affiliation(s)
- Douglas W Wacker
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh EH8 9XD, UK
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53
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Bao AM, Ruhé HG, Gao SF, Swaab DF. Neurotransmitters and neuropeptides in depression. HANDBOOK OF CLINICAL NEUROLOGY 2012; 106:107-36. [PMID: 22608619 DOI: 10.1016/b978-0-444-52002-9.00008-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- A-M Bao
- Department of Neurobiology, Zhejiang University School of Medicine, Hangzhou, China.
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54
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Moritoh S, Sato K, Okada Y, Koizumi A. Endogenous arginine vasopressin-positive retinal cells in arginine vasopressin-eGFP transgenic rats identified by immunohistochemistry and reverse transcriptase-polymerase chain reaction. Mol Vis 2011; 17:3254-61. [PMID: 22194651 PMCID: PMC3244476] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2011] [Accepted: 12/12/2011] [Indexed: 11/19/2022] Open
Abstract
PURPOSE Recently, arginine vasopressin (AVP) has been revealed to have diverse functional roles in nervous tissues beyond that of a vasoconstrictor. Several previous studies have indicated the existence of AVP in the retina, but the source of AVP has not been determined. The objective of the present study was to address the question of whether retinal cells have the ability to synthesize endogenous AVP to act in a paracrine or autocrine manner. METHODS We used AVP-eGFP transgenic rats to find endogenous AVP-positive cells in the retina by immunohistochemistry with an AVP antibody and a GFP antibody. We also examined AVP mRNA and AVP receptor genes by reverse transcriptase (RT)-PCR of dissociated GFP-positive cells and whole retinas. RESULTS Endogenous AVP-positive cells were found in the ganglion cell layer and inner nuclear layer of the retina of AVP-eGFP transgenic rats by immunohistochemistry. As indicated by the results of RT-PCR of dissociated GFP-positive cells, these cells have the ability to synthesize endogenous AVP, as well as transgenic AVP-eGFP. In addition, the V1a and V1b AVP receptors were found in the wild-type rat retina by whole retina RT-PCR, but the V2 receptor was not detectable. In dissociated AVP-eGFP-positive cells, no AVP receptor was detected by RT-PCR. Moreover, AVP secretion was not detected by stimulation with a high potassium (50 mM) solution. CONCLUSIONS In the rat retina, we found retinal cells that have the ability to synthesize endogenous AVP, and that the retina possesses V1a and V1b AVP receptors. Taken together, these results suggest that the retina has an intrinsic AVP-synthesizing and -receiving mechanism that can operate in a paracrine manner via V1a and V1b receptors.
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Affiliation(s)
- Satoru Moritoh
- Department of Cell Physiology, National Institute for Physiological Sciences, Okazaki, Japan
| | - Kaori Sato
- Department of Cell Physiology, National Institute for Physiological Sciences, Okazaki, Japan
| | - Yasunobu Okada
- Department of Cell Physiology, National Institute for Physiological Sciences, Okazaki, Japan,Department of Physiological Sciences, School of Life Science, The Graduate University for Advanced Studies (SOKENDAI), Okazaki, Japan
| | - Amane Koizumi
- Department of Cell Physiology, National Institute for Physiological Sciences, Okazaki, Japan,Section of Communications and Public Liaison, National Institute for Physiological Sciences, Okazaki, Japan,Department of Physiological Sciences, School of Life Science, The Graduate University for Advanced Studies (SOKENDAI), Okazaki, Japan
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55
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Tobin VA, Douglas AJ, Leng G, Ludwig M. The involvement of voltage-operated calcium channels in somato-dendritic oxytocin release. PLoS One 2011; 6:e25366. [PMID: 22028774 PMCID: PMC3197583 DOI: 10.1371/journal.pone.0025366] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2010] [Accepted: 09/02/2011] [Indexed: 11/18/2022] Open
Abstract
Magnocellular neurons of the supraoptic nucleus (SON) secrete oxytocin and vasopressin from axon terminals in the neurohypophysis, but they also release large amounts of peptide from their somata and dendrites, and this can be regulated both by activity-dependent Ca2+ influx and by mobilization of intracellular Ca2+. This somato-dendritic release can also be primed by agents that mobilise intracellular Ca2+, meaning that the extent to which it is activity-dependent, is physiologically labile. We investigated the role of different Ca2+ channels in somato-dendritic release; blocking N-type channels reduced depolarisation-induced oxytocin release from SONs in vitro from adult and post-natal day 8 (PND-8) rats, blocking L-type only had effect in PND-8 rats, while blocking other channel types had no significant effect. When oxytocin release was primed by prior exposure to thapsigargin, both N- and L-type channel blockers reduced release, while P/Q and R-type blockers were ineffective. Using confocal microscopy, we found immunoreactivity for Cav1.2 and 1.3 channel subunits (which both form L-type channels), 2.1 (P/Q type), 2.2 (N-type) and 2.3 (R-type) in the somata and dendrites of both oxytocin and vasopressin neurons, and the intensity of the immunofluorescence signal for different subunits differed between PND-8, adult and lactating rats. Using patch-clamp electrophysiology, the N-type Ca2+ current density increased after thapsigargin treatment, but did not alter the voltage sensitivity of the channel. These results suggest that the expression, location or availability of N-type Ca2+ channels is altered when required for high rates of somato-dendritic peptide release.
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Affiliation(s)
- Vicky A. Tobin
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
| | - Alison J. Douglas
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
| | - Gareth Leng
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
| | - Mike Ludwig
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
- * E-mail:
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56
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Abstract
Endocannabinoids (eCBs) are feedback messengers in the nervous system that act at the presynaptic nerve terminal to inhibit transmitter release. Here we report that in brain slices from rat, eCBs are released from vasopressin (VP) neurons in the paraventricular nucleus of the hypothalamus following coincident bursts of presynaptic and postsynaptic spiking. eCBs transiently depress glutamate release from excitatory terminals and, in doing so, prevent the synapses from undergoing long-term depression (LTD). Specifically, we show that blockade of CB1 receptors unmasks LTD following coincident presynaptic and postsynaptic activity. This LTD is presynaptic in nature, but requires the release of the opioid peptide dynorphin from the postsynaptic neuron. Dynorphin release and subsequent LTD require the activation of postsynaptic metabotropic glutamate receptors (mGluRs). Our findings indicate that eCBs, by transiently depressing glutamate release, limit mGluR activation and indirectly gate release of dynorphin from the postsynaptic neuron. We propose that eCBs, in addition to their well described role in the rapid modulation of transmitter release from the nerve terminal, also regulate the release of other retrograde transmitters and thus encode for multiple temporal windows of synaptic plasticity.
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57
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Wacker DW, Engelmann M, Tobin VA, Meddle SL, Ludwig M. Vasopressin and social odor processing in the olfactory bulb and anterior olfactory nucleus. Ann N Y Acad Sci 2011; 1220:106-16. [PMID: 21388408 DOI: 10.1111/j.1749-6632.2010.05885.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Central vasopressin facilitates social recognition and modulates numerous complex social behaviors in mammals, including parental behavior, aggression, affiliation, and pair-bonding. In rodents, social interactions are primarily mediated by the exchange of olfactory information, and there is evidence that vasopressin signaling is important in brain areas where olfactory information is processed. We recently discovered populations of vasopressin neurons in the main and accessory olfactory bulbs and anterior olfactory nucleus that are involved in the processing of social odor cues. In this review, we propose a model of how vasopressin release in these regions, potentially from the dendrites, may act to filter social odor information to facilitate odor-based social recognition. Finally, we discuss recent human research linked to vasopressin signaling and suggest that our model of priming-facilitated vasopressin signaling would be a rewarding target for further studies, as a failure of priming may underlie pathological changes in complex behaviors.
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Affiliation(s)
- Douglas W Wacker
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
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58
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Gamrani H, Elgot A, El Hiba O, Fèvre–Montange M. Cellular plasticity in the supraoptic and paraventricular nuclei after prolonged dehydration in the desert rodent Meriones shawi: Vasopressin and GFAP immunohistochemical study. Brain Res 2011; 1375:85-92. [DOI: 10.1016/j.brainres.2010.10.049] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2010] [Revised: 10/08/2010] [Accepted: 10/14/2010] [Indexed: 10/18/2022]
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59
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Komori Y, Tanaka M, Kuba M, Ishii M, Abe M, Kitamura N, Verkhratsky A, Shibuya I, Dayanithi G. Ca(2+) homeostasis, Ca(2+) signalling and somatodendritic vasopressin release in adult rat supraoptic nucleus neurones. Cell Calcium 2010; 48:324-32. [PMID: 21047683 DOI: 10.1016/j.ceca.2010.10.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2010] [Revised: 09/29/2010] [Accepted: 10/01/2010] [Indexed: 10/18/2022]
Abstract
Multiple mechanisms that maintain Ca(2+) homeostasis and provide for Ca(2+) signalling operate in the somatas and neurohypophysial nerve terminals of supraoptic nucleus (SON) neurones. Here, we examined the Ca(2+) clearance mechanisms of SON neurones from adult rats by monitoring the effects of the selective inhibition of different Ca(2+) homeostatic molecules on cytosolic Ca(2+) ([Ca(2+)](i)) transients in isolated SON neurones. In addition, we measured somatodendritic vasopressin (AVP) release from intact SON tissue in an attempt to correlate it with [Ca(2+)](i) dynamics. When bathing the cells in a Na(+)-free extracellular solution, thapsigargin, cyclopiazonic acid (CPA), carbonyl cyanide 3-chlorophenylhydrazone (CCCP), and the inhibitor of plasma membrane Ca(2+)-ATPase (PMCA), La(3+), all significantly slowed down the recovery of depolarisation (50 mM KCl)-induced [Ca(2+)](i) transients. The release of AVP was stimulated by 50 mM KCl, and the decline in the peptide release was slowed by Ca(2+) transport inhibitors. In contrast to previous reports, our results show that in the fully mature adult rats: (i) all four Ca(2+) homeostatic pathways, the Na(+)/Ca(2+) exchanger, the endoplasmic reticulum Ca(2+) pump, the plasmalemmal Ca(2+) pump and mitochondria, are complementary in actively clearing Ca(2+) from SON neurones; (ii) somatodendritic AVP release closely correlates with intracellular [Ca(2+)](i) dynamics; (iii) there is (are) Ca(2+) clearance mechanism(s) distinct from the four outlined above; and (iv) Ca(2+) homeostatic systems in the somatas of SON neurones differ from those expressed in their terminals.
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Affiliation(s)
- Yoko Komori
- University of Occupational and Environmental Health School of Medicine, Kitakyushu 807-8555, Japan
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60
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Kodavanti PRS, Curras-Collazo MC. Neuroendocrine actions of organohalogens: thyroid hormones, arginine vasopressin, and neuroplasticity. Front Neuroendocrinol 2010; 31:479-96. [PMID: 20609372 DOI: 10.1016/j.yfrne.2010.06.005] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2010] [Revised: 06/22/2010] [Accepted: 06/25/2010] [Indexed: 02/08/2023]
Abstract
Organohalogen compounds are global environmental pollutants. They are highly persistent, bioaccumulative, and cause adverse effects in humans and wildlife. Because of the widespread use of these organohalogens in household items and consumer products, indoor contamination may be a significant source of human exposure, especially for children. One significant concern with regard to health effects associated with exposure to organohalogens is endocrine disruption. This review focuses on PCBs and PBDEs as old and new organohalogens, respectively, and their effects on two neuroendocrine systems; thyroid hormones and the arginine vasopressin system (AVP). Regarding neuroendocrine effects of organohalogens, there is considerable information on the thyroid system as a target and evidence is now accumulating that the AVP system and associated functions are also susceptible to disruption. AVP-mediated functions such as osmoregulation, cardiovascular function as well as social behavior, sexual function and learning/memory are discussed. For both thyroid and AVP systems, the timing of exposure seems to play a major role in the outcome of adverse effects. The mechanism of organohalogen action is well understood for the thyroid system. In comparison, this aspect is understudied in the AVP system but some similarities in neural processes, shown to be targeted by these pollutants, serve as promising possibilities for study. One challenge in understanding modes of action within neuroendocrine systems is their complexity stemming, in part, from interdependent levels of organization. Further, because of the interplay between neuroendocrine and neural functions and behavior, further investigation into organohalogen-mediated effects is warranted and may yield insights with wider scope. Indeed, the current literature provides scattered evidence regarding the role of organohalogen-induced neuroendocrine disruption in the neuroplasticity related to both learning functions and brain structure but future studies are needed to establish the role of endocrine disruption in nervous system function and development.
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Affiliation(s)
- Prasada Rao S Kodavanti
- Neurotoxicology Branch, Toxicity Assessment Division, B 105-06, National Health and Environmental Effects Research Laboratory, Office of Research and Development, US Environmental Protection Agency, Research Triangle Park, NC 27711, USA.
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61
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Iremonger KJ, Benediktsson AM, Bains JS. Glutamatergic synaptic transmission in neuroendocrine cells: Basic principles and mechanisms of plasticity. Front Neuroendocrinol 2010; 31:296-306. [PMID: 20347860 DOI: 10.1016/j.yfrne.2010.03.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2009] [Revised: 03/21/2010] [Accepted: 03/23/2010] [Indexed: 11/27/2022]
Abstract
Glutamate synapses drive the output of neuroendocrine cells in the hypothalamus, but until recently, relatively little was known about the fundamental properties of transmission at these synapses. Here we review recent advances in the understanding of glutamate signals in magnocellular neurosecretory cells (MNCs) in the paraventricular (PVN) and supraoptic nuclei (SON) of the hypothalamus that serve as the last step in synaptic integration before neurohormone release. While these synapses exhibit many similarities with other glutamate synapses described throughout the brain, they also exhibit a number of unique properties that are particularly well suited to the physiology of this system and will be discussed here. In addition, a number of recent studies begin to provide insights into new forms of synaptic plasticity that may be common in other brain regions, but in these cells, may serve important adaptive roles.
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Affiliation(s)
- Karl J Iremonger
- Hotchkiss Brain Institute and Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, Canada T2N 4N1
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Salmina AB, Lopatina O, Ekimova MV, Mikhutkina SV, Higashida H. CD38/cyclic ADP-ribose system: a new player for oxytocin secretion and regulation of social behaviour. J Neuroendocrinol 2010; 22:380-92. [PMID: 20141572 DOI: 10.1111/j.1365-2826.2010.01970.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Oxytocin is important for regulating a number of physiological processes. Disruption of the secretion, metabolism or action of oxytocin results in an impairment of reproductive function, social and sexual behaviours, and stress responses. This review discusses current views on the regulation and autoregulation of oxytocin release in the hypothalamic-neurohypophysial system, with special focus on the activity of the CD38/cADP-ribose system as a new component in this regulation. Data from our laboratories indicate that an impairment of this system results in alterations of oxytocin secretion and abnormal social behaviour, thus suggesting new clues that help in our understanding of the pathogenesis of neurodevelopmental disorders.
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Affiliation(s)
- A B Salmina
- Department of Biochemistry, Medical, Pharmaceutical and Toxicological Chemistry, Krasnoyarsk State Medical University, Krasnoyarsk 660022, Russia.
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63
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Bao AM, Swaab DF. Corticotropin-Releasing Hormone and Arginine Vasopressin in Depression. HORMONES OF THE LIMBIC SYSTEM 2010; 82:339-65. [DOI: 10.1016/s0083-6729(10)82018-7] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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64
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Kato K, Kannan H, Ohta H, Kemuriyama T, Maruyama S, Tandai-Hiruma M, Sato Y, Nakazato M, Nishimori T, Ishida Y, Onaka T, Nishida Y. Central endogenous vasopressin induced by central salt-loading participates in body fluid homeostasis through modulatory effects on neurones of the paraventricular nucleus in conscious rats. J Neuroendocrinol 2009; 21:921-34. [PMID: 19732288 DOI: 10.1111/j.1365-2826.2009.01915.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Peripherally secreted arginine vasopressin (AVP) plays a role in controlling body fluid homeostasis, and central endogenous AVP acts as a neurotransmitter or neuromodulator. The limbic system, which appears to exert an inhibitory effect on the endocrine hypothalamus, is also innervated by fibres that contain AVP. We examined whether central endogenous AVP is also involved in the control of body fluid homeostasis. To explore this possibility, we examined neuronal activity in the paraventricular nucleus of the hypothalamus (PVN), periventricular parts of the PVN and limbic brain areas, as well as AVP mRNA expression in the PVN and the peripheral secretion of AVP after central salt-loading in rats that had been pretreated i.c.v. with the AVP V(1) receptor antagonist OPC-21268. Neuronal activity in the PVN evaluated in terms of Fos-like immunoreactivity (FLI), especially in the parvocellular subdivisions, was suppressed. On the other hand, FLI was enhanced in the lateral septum, the bed nucleus of the stria terminalis and the anterior hypothalamic area. Similarly, AVP mRNA expression was enhanced in the magnocellular subnucleus of the PVN, despite the lack of a significant difference in the peripheral AVP level between OPC-21268- and vehicle-pretreated groups. We recorded renal sympathetic nerve activity (RSNA) as sympathetic nerve outflow during central salt-loading. The suppression of RSNA was significantly attenuated by i.c.v. pretreatment with OPC-21268. These results suggest that the suppression of RSNA during central salt-loading might be the result of a decrease in neuronal activity in the parvocellular subdivisions of the PVN via the inhibitory action of central endogenous AVP. The parvocellular and magnocellular neurones in the PVN might show different responses to central salt-loading to maintain body fluid homeostasis as a result of the modulatory role of central endogenous AVP.
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Affiliation(s)
- K Kato
- Department of Physiology, National Defense Medical College, Saitama, Japan.
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65
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Abstract
Opioid signaling in the CNS is critical for controlling cellular excitability, yet the conditions under which endogenous opioid peptides are released and the precise mechanisms by which they affect synaptic transmission remain poorly understood. The opioid peptide dynorphin is present in the soma and dendrites of vasopressin neurons in the hypothalamus and dynamically controls the excitability of these cells in vivo. Here, we show that dynorphin is released from dendritic vesicles in response to postsynaptic activity and acts in a retrograde manner to inhibit excitatory synaptic transmission. This inhibition, which requires the activation of kappa-opioid receptors, results from a reduction in presynaptic release of glutamate vesicles. The opioid inhibition is downstream of Ca(2+) entry and is likely mediated by a direct modulation of presynaptic fusion machinery. These findings demonstrate that neurons may self-regulate their excitability through the dendritic release of opioids to inhibit excitatory synaptic transmission.
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66
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Rossi NF, Maliszewska-Scislo M. Role of paraventricular nucleus vasopressin V1A receptors in the response to endothelin 1 activation of the subfornical organ in the rat. JOURNAL OF PHYSIOLOGY AND PHARMACOLOGY : AN OFFICIAL JOURNAL OF THE POLISH PHYSIOLOGICAL SOCIETY 2008; 59 Suppl 8:47-59. [PMID: 19258664 PMCID: PMC2743721] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Received: 10/24/2008] [Accepted: 11/28/2008] [Indexed: 05/27/2023]
Abstract
Endothelin (ET) acts at selected brain loci to elicit a pressor response and vasopressin (AVP) secretion. The pressor action of centrally acting ET is mediated via enhanced efferent sympathetic nerve activity. ET-induced VP secretion depends upon the ET receptor subtype and the brain region involved. ET(A)R activation at the subfornical organ (SFO) increases mean arterial pressure and renal sympathetic nerve activity (RSNA) as well as AVP secretion in awake rats. These effects are only partly mediated by glutamatergic receptors in paraventricular nucleus (PVN). Recent data indicate dendritic release of AVP may act as a neurotransmitter. We therefore hypothesized that dendritic release of AVP from magnocellular PVN neurons contributes to the increase in arterial pressure and RSNA due to ET(A) receptor activation at SFO. Male Sprague Dawley rats equipped with vascular catheters, renal nerve electrodes, and intracerebral cannulae directed into SFO and magnocellular PVN bilaterally were studied 48hr after recovery in the awake state. Hemodynamic and neural parameters were monitored continuously. Microinjection of 5 pmol ET1 into SFO increased mean arterial pressure by 15.8 +/- 4.2 mmHg accompanied by reflex decreases in heart rate and RSNA. Microinjection of 100 ng of the V(1a) receptor antagonist alone bilaterally into the PVN did not change baseline parameters; however, the pressor response to ET1 was significantly attenuated with mean arterial pressure increasing only by 6.1 +/- 3.0 mmHg (P<0.05). Reflex changes in heart rate and RSNA did not change. These findings support the concept that dendritic release of VP from magnocellular neurons within the PVN mediates, at least in part, the pressor response to ET(A) receptor activation at the SFO.
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Affiliation(s)
- N F Rossi
- Department of Medicine, Wayne State University School of Medicine, Detroit, Michigan 48201, USA.
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67
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Summy-Long JY, Hu S, Long A, Phillips TM. Interleukin-1beta release in the supraoptic nucleus area during osmotic stimulation requires neural function. J Neuroendocrinol 2008; 20:1224-32. [PMID: 18752652 PMCID: PMC2585151 DOI: 10.1111/j.1365-2826.2008.01783.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Interleukin (IL)-1beta is present throughout the magnocellular neuroendocrine system and co-depletes with oxytocin and vasopressin from the neural lobe during salt-loading. To examine whether IL-1beta is released from the dendrites/soma of magnocellular neurones during osmotic stimulation, microdialysis adjacent to the supraoptic nucleus (SON) in conscious rats was combined with immunocapillary electrophoresis and laser-induced fluorescence detection to quantify cytokine in 5-min dialysates collected before (0-180 min; basal), and after (180-240 min), hypertonic saline injected s.c. (1.5 m NaCl). Osmotic release of IL-1beta was compared after inhibiting local voltage-gated channels for Na+ (tetrodotoxin) and Ca2+ (cadmium and nickel) or by reducing intracellular Ca2+ stores (thapsigargin). Immunohistochemistry combined with microdialysis was used to localise cytokine sources (IL-1beta+) and microglia (OX-42+). Under conditions of microdialysis, the basal release of IL-1beta+ in the SON area was measurable and stable (pg/ml; mean +/- SEM) from 0-60 min (2.2 +/- 0.06), 60-120 min (2.32 +/- 0.05) and 120-180 min (2.33 +/- 0.06), likely originating locally from activated microglia (OX42+; IL-1beta+; ameboid, hypertrophied) and magnocellular neurones expressing IL-1beta. In response to osmotic stimulation, IL-1beta increased progressively in dialysates of the SON area by a mechanism dependent on intracellular Ca2+ stores sensitive to thapsigargin and, similar to dendritic secretion of oxytocin and vasopressin, required local voltage-gated Na+ and Ca2+ channels for activation by osmoregulatory pathways from the forebrain. During osmotic stimulation, neurally dependent release of IL-1beta in the SON area likely upregulates osmosensitive cation currents on magnocellular neurones (observed in vitro by others), to facilitate dendritic release of neurohypophysial hormones.
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Affiliation(s)
- J Y Summy-Long
- Department of Neural and Behavioral Sciences, Penn State College of Medicine, Hershey, PA 17033, USA.
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68
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Alonso G, Gallibert E, Lafont C, Guillon G. Intrahypothalamic angiogenesis induced by osmotic stimuli correlates with local hypoxia: a potential role of confined vasoconstriction induced by dendritic secretion of vasopressin. Endocrinology 2008; 149:4279-88. [PMID: 18483147 DOI: 10.1210/en.2008-0387] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We have previously shown that hyperosmotic stimulation of adult Wistar rats induces local angiogenesis within hypothalamic magnocellular nuclei, in relation to the secretion of vascular endothelial growth factor (VEGF) by the magnocellular neurons. The present study aimed at understanding how osmotic stimulus relates to increased VEGF secretion. We first demonstrate a correlation between increased VEGF secretion and local hypoxia. Osmotic stimulation is known to stimulate the metabolic activity of hypothalamic magnocellular neurons producing arginine vasopressin (AVP) and to increase the secretion of AVP, both by axon terminals into the circulation and by dendrites into the extracellular space. In AVP-deficient Brattleboro rats, the dramatic activation of magnocellular hypothalamic neurons failed to induce hypoxia, VEGF expression, or angiogenesis, suggesting a major role of hypothalamic AVP. A possible involvement of dendritic AVP release is supported by the findings that 1) hypoxia and angiogenesis were not observed in non osmotically stimulated Wistar rats in which circulating AVP was increased by the prolonged infusion of exogenous AVP, 2) contractile arterioles afferent to the magnocellular nuclei were strongly constricted by the perivascular application of AVP via V1a receptors (V1a-R) stimulation, and 3) after the intracerebral or ip administrations of selective V1a-R antagonists to osmotically stimulated rats, hypothalamic hypoxia and angiogenesis were or were not inhibited, respectively. Together, these data strongly suggest that the angiogenesis induced by osmotic stimulation relates to tissue hypoxia resulting from the constriction of local arterioles, via the stimulation of perivascular V1a-R by AVP locally released from dendrites.
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Affiliation(s)
- Gérard Alonso
- Institut de Génomique Fonctionnelle, Département d'Endocrinologie, 141 rue de la Cardonille, F-34094 Montpellier Cedex 05, France
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69
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Yoshii T, Sakamoto H, Kawasaki M, Ozawa H, Ueta Y, Onaka T, Fukui K, Kawata M. The single-prolonged stress paradigm alters both the morphology and stress response of magnocellular vasopressin neurons. Neuroscience 2008; 156:466-74. [PMID: 18723079 DOI: 10.1016/j.neuroscience.2008.07.049] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2008] [Revised: 07/11/2008] [Accepted: 07/17/2008] [Indexed: 10/21/2022]
Abstract
Vasopressin (AVP) plays an important role in anxiety-related and social behaviors. Single-prolonged stress (SPS) has been established as an animal acute severe stress model and has been shown to induce a lower adrenocorticotropic hormone (ACTH) response upon cortisol challenge. Here, we show results from immunoassays for AVP, ACTH, and corticosterone (CORT), and in situ hybridizations for AVP mRNA performed 7 days after SPS exposure. Immunofluorescence for AVP was also performed during the 7-day period following SPS exposure and after an additional forced swimming stress paradigm. We observed that the plasma concentrations of AVP, ACTH, and CORT were not altered by SPS; ACTH content in the pituitary and AVP mRNA expression in the supraoptic nucleus (SON) were significantly reduced by SPS. During the 7-day period following SPS, the intensity of immunoreactivity, the size of the soma, and the immunoreactive optical density of the dendrites of AVP neurons in the SON all increased. An apparent reduction in the intensity of AVP immunoreactivity was observed in the SON at 4 h after additional stress. Additional forced swimming led to a rapid increase in the dendritic AVP content only in the controls and not in the SPS-treated rats. These findings suggest that AVP is a potential biomarker for past exposure to severe stress and that alterations in AVP may affect the development of pathogenesis in stress-related disorders.
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Affiliation(s)
- T Yoshii
- Department of Psychiatry, Kyoto Prefectural University of Medicine, Graduate School of Medical Science, Kawaramachi-Hirokoji, Kyoto 602-8566, Japan
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70
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Abstract
Information flow through neurones was historically considered to be linear, with dendrites receiving information from incoming synaptic terminals, the soma processing the information and the axon carrying it to the terminal that synapses upon another cell or end organ. However, recent studies have shown that dendrites can release transmitters themselves, and thereby communicate with neighbouring structures, whether these are adjacent neurones or incoming synapses. Due to their anatomical features, the magnocellular vasopressin and oxytocin containing neurones of the hypothalamic supraoptic and paraventricular nuclei and the dopamine neurones of the substantia nigra have revealed important aspects of dendritic function including mechanisms of dendritic transmitter release.
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Affiliation(s)
- F Bergquist
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, UK
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71
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Quinlan ME, Alberto CO, Hirasawa M. Short-term potentiation of mEPSCs requires N-, P/Q- and L-type Ca2+ channels and mitochondria in the supraoptic nucleus. J Physiol 2008; 586:3147-61. [PMID: 18467369 DOI: 10.1113/jphysiol.2007.148957] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The glutamatergic synapses of the supraoptic nucleus display a unique activity-dependent plasticity characterized by a barrage of tetrodotoxin-resistant miniature EPSCs (mEPSCs) persisting for 5-20 min, causing postsynaptic excitation. We investigated how this short-term synaptic potentiation (STP) induced by a brief high-frequency stimulation (HFS) of afferents was initiated and maintained without lingering presynaptic firing, using in vitro patch-clamp recording on rat brain slices. We found that following the immediate rise in mEPSC frequency, STP decayed with two-exponential functions indicative of two discrete phases. STP depends entirely on extracellular Ca(2+) which enters the presynaptic terminals through voltage-gated Ca(2+) channels but also, to a much lesser degree, through a pathway independent of these channels or reverse mode of the plasma membrane Na(+)-Ca(2+) exchanger. Initiation of STP is largely mediated by any of the N-, P/Q- or L-type channels, and only a simultaneous application of specific blockers for all these channels attenuates STP. Furthermore, the second phase of STP is curtailed by the inhibition of mitochondrial Ca(2+) uptake or mitochondrial Na(+)-Ca(2+) exchanger. mEPSCs amplitude is also potentiated by HFS which requires extracellular Ca(2+). In conclusion, induction of mEPSC-STP is redundantly mediated by presynaptic N-, P/Q- and L-type Ca(2+) channels while the second phase depends on mitochondrial Ca(2+) sequestration and release. Since glutamate influences unique firing patterns that optimize hormone release by supraoptic magnocellular neurons, a prolonged barrage of spontaneous excitatory transmission may aid in the induction of respective firing activities.
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Affiliation(s)
- Michelle E Quinlan
- Division of BioMedical Sciences, Faculty of Medicine, Memorial University, 300 Prince Philip Drive, St John's, NL A1B 3V6, Canada
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72
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Frank E, Landgraf R. The vasopressin system--from antidiuresis to psychopathology. Eur J Pharmacol 2008; 583:226-42. [PMID: 18275951 DOI: 10.1016/j.ejphar.2007.11.063] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2007] [Revised: 11/13/2007] [Accepted: 11/14/2007] [Indexed: 01/04/2023]
Abstract
Vasopressin is a neuropeptide with multiple functions. In addition to its predominantly antidiuretic action after peripheral secretion from the posterior pituitary, it seems to fulfill--together with its receptor subtype--all requirements for a neuropeptide system critically involved in higher brain functions, including cognitive abilities and emotionality. Following somatodendritic and axonal release in distinct brain areas, vasopressin acts as a neuromodulator and neurotransmitter in multiple and varying modes of interneuronal communication. Accordingly, changes in vasopressin expression and release patterns may have wide-spread consequences. As shown in mice, rats, voles, and humans, central vasopressin release along a continuum may be beneficial to the individual, serving to adjust physiology and behavior in stressful scenarios, possibly at the potential expense of increasing susceptibility to disease. Indeed, if over-expressed and over-released, it may contribute to hyper-anxiety and depression-like behaviors. A vasopressin deficit, in turn, may cause signs of both diabetes insipidus and total hypo-anxiety. The identification of genetic polymorphisms underlying these phenomena does not only explain individual variation in social memory and emotionality, but also help to characterize potential targets for therapeutic interventions. The capability of both responding to stressful stimuli and mediating genetic polymorphisms makes the vasopressin system a key mediator for converging (i.e., environmentally and genetically driven) behavioral regulation.
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Affiliation(s)
- Elisabeth Frank
- Department of Behavioral Neuroendocrinology, Max Planck Institute of Psychiatry, Kraepelinstr. 2, 80804 Munich, Germany
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73
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Rostène W, Kitabgi P, Parsadaniantz SM. Chemokines: a new class of neuromodulator? Nat Rev Neurosci 2007; 8:895-903. [PMID: 17948033 DOI: 10.1038/nrn2255] [Citation(s) in RCA: 249] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Chemokines are not only found in the immune system or expressed in inflammatory conditions: they are constitutively present in the brain in both glial cells and neurons. Recently, the possibility has been raised that they might act as neurotransmitters or neuromodulators. Although the evidence is incomplete, emerging data show that chemokines have several of the characteristics that define neurotransmitters. Moreover, their physiological actions resemble those of neuromodulators in the sense that chemokines usually have few effects by themselves in basal conditions, but modify the induced release of neurotransmitters or neuropeptides. These findings, together with the pharmacological development of agonists and antagonists that are selective for chemokine receptors and can cross the blood-brain barrier, open a new era of research in neuroscience.
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Affiliation(s)
- William Rostène
- INSERM-UPMC 732, Hôpital St Antoine, 184 Rue du Fg St Antoine, 75012 Paris, France.
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74
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Abstract
F-actin remodelling has been implicated in regulated secretion from many cell types, in particular secretion from neuron axon terminals and neuroendocrine cell types. Cortical F-actin has long been postulated to act as a barrier to vesicle movement and hence to inhibit secretion; however, more recent studies point to F-actin remodelling providing both supporting and restraining roles in secretion. Magnocellular neurons of the supraoptic nucleus secrete either oxytocin or vasopressin from their dendrites as well as their axon terminals; and peptide release from these two compartments can be differentially controlled to allow secretion from one compartment in isolation from the other. While oxytocin and vasopressin secretion can be provoked by F-actin depolymerization in both compartments, acutely stimulated secretion is dependent on F-actin remodelling in dendrites but not axon terminals, suggesting that F-actin plays a different role in regulating the readily releasable pool of secretory vesicles in the two compartments. In addition, activity-dependent secretion from the dendritic compartment can be primed by prior exposure to agents, including oxytocin, that stimulate release of Ca2+ from intracellular stores. While remodelling of F-actin is involved, it is not solely responsible for priming secretory responses.
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75
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Coburn CG, Currás-Collazo MC, Kodavanti PRS. In vitro effects of environmentally relevant polybrominated diphenyl ether (PBDE) congeners on calcium buffering mechanisms in rat brain. Neurochem Res 2007; 33:355-64. [PMID: 17846885 DOI: 10.1007/s11064-007-9430-x] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2007] [Accepted: 06/29/2007] [Indexed: 11/26/2022]
Abstract
Polybrominated diphenyl ethers (PBDEs) are widely used as additive flame-retardants and have been detected in human blood, adipose tissue, and breast milk. Developmental and long-term exposures to these chemicals may pose a human health risk, especially to children. We have previously demonstrated that polychlorinated biphenyls (PCBs), which are structurally similar to PBDEs and cause neurotoxicity, perturb intracellular signaling events including calcium homeostasis and protein kinase C translocation, which are critical for neuronal function and development of the nervous system. The objective of the present study was to test whether environmentally relevant PBDE congeners 47 and 99 are also capable of disrupting Ca(2+) homeostasis. Calcium buffering was determined by measuring (45)Ca(2+)-uptake by microsomes and mitochondria, isolated from adult male rat brain (frontal cortex, cerebellum, hippocampus, and hypothalamus). Results show that PBDEs 47 and 99 inhibit both microsomal and mitochondrial (45)Ca(2+)-uptake in a concentration-dependent manner. The effect of these congeners on (45)Ca(2+)-uptake is similar in all four brain regions though the hypothalamus seems to be slightly more sensitive. Among the two preparations, the congeners inhibited (45)Ca(2+)-uptake in mitochondria to a greater extent than in microsomes. These results indicate that PBDE 47 and PBDE 99 congeners perturb calcium signaling in rat brain in a manner similar to PCB congeners, suggesting a common mode of action of these persistent organic pollutants.
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Affiliation(s)
- Cary G Coburn
- Environmental Toxicology Graduate Program, University of California, Riverside, CA 92521, USA
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76
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Tobin VA, Ludwig M. The role of the actin cytoskeleton in oxytocin and vasopressin release from rat supraoptic nucleus neurons. J Physiol 2007; 582:1337-48. [PMID: 17478532 PMCID: PMC2075266 DOI: 10.1113/jphysiol.2007.132639] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Magnocellular neurons of the supraoptic nucleus (SON) can differentially control peptide release from the somato/dendritic and axon terminal compartment. Dendritic release can be selectively regulated through activation of intracellular calcium stores by calcium mobilizers such as thapsigargin (TG), resulting in preparation (priming) of somato/dendritic peptide pools for subsequent activity-dependent release. As dynamic modulation of the actin cytoskeleton is implicated in secretion from synaptic terminals and from several types of neuroendocrine cells, we studied its involvement in oxytocin and vasopressin release from SON neurons. Confocal image analysis of the somata revealed that the normally continuous cortical band of F-actin is disrupted after high potassium (K(+), 50 mm) or TG (200 nm) stimulation. The functional importance of actin remodelling was studied using cell-permeable actin polymerizing (jasplakinolide, 2 microm) or depolymerizing agents (latrunculin B, 5 microm) to treat SON and neural lobe (NL) explants in vitro and measure high K(+)-induced oxytocin and vasopressin release. Latrunculin significantly enhanced, and jasplakinolide inhibited, high-K(+)-evoked somato/dendritic peptide release, while release from axon terminals was not altered, suggesting that high-K(+)-evoked release in the SON, but not the NL, requires depolymerization of the actin cytoskeleton. TG-induced priming of somato/dendritic release was also blocked by jasplakinolide and latrunculin, suggesting that priming involves changes in actin remodelling.
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Affiliation(s)
- Vicky A Tobin
- Centre for Integrative Physiology, University of Edinburgh, George Square, Edinburgh EH8 9XD, UK
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77
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Douglas AJ, Johnstone LE, Leng G. Neuroendocrine mechanisms of change in food intake during pregnancy: a potential role for brain oxytocin. Physiol Behav 2007; 91:352-65. [PMID: 17512024 DOI: 10.1016/j.physbeh.2007.04.012] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
During pregnancy body weight, and particularly adiposity, increase, due to hyperphagia rather than decreased energy metabolism. These physiological adaptations provide the growing fetus(es) with nutrition and prepare the mother for the metabolically-demanding lactation period following birth. Mechanisms underlying the hyperphagia are still poorly understood. Although the peripheral signals that drive appetite and satiety centers of the brain are increased in pregnancy, the brain may become insensitive to their effects. For example, leptin secretion increases but hypothalamic resistance to leptin actions develops. However, several adaptations in hypothalamic neuroendocrine systems may converge to increase ingestive behavior. Oxytocin is one of the anorectic hypothalamic neuropeptides. Oxytocin neurons, both centrally-projecting parvocellular oxytocin neurons and central dendritic release of oxytocin from magnocellular neurons, may play a key role in regulating energy intake. During feeding in non-pregnant rats, magnocellular oxytocin neurons, especially those in the supraoptic nucleus, become strongly activated indicating their imminent role in meal termination. However, in mid-pregnancy the excitability of these neurons is reduced, central dendritic oxytocin release is inhibited and patterns of oxytocin receptor binding in the brain alter. Our recent data suggest that lack of central oxytocin action may partly contribute to maternal hyperphagia. However, although opioid inhibition is a major factor in oxytocin neuron restraint during pregnancy and opioids enhance food intake, an increase in opioid orexigenic actions were not observed. While changes in several central input pathways to oxytocin neurons are likely to be involved, the high level of progesterone secretion during pregnancy is probably the ultimate trigger for the adaptations.
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Affiliation(s)
- Alison J Douglas
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, UK.
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78
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Chiti Z, Teschemacher AG. Exocytosis of norepinephrine at axon varicosities and neuronal cell bodies in the rat brain. FASEB J 2007; 21:2540-50. [PMID: 17405853 DOI: 10.1096/fj.06-7342com] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Norepinephrine secretion from central neurons was widely assumed to occur by exocytosis, but the essential characteristics of this process remained unknown. We developed an approach to study it directly by amperometry using carbon fiber microelectrodes in organotypic rat brainstem slice cultures. Noradrenergic neurons from areas A1 and A2 were fluorescently labeled by an adenoviral vector with noradrenergic-specific promoter. Quantal events, consistent with exocytotic release of norepinephrine, were registered at noradrenergic axonal varicosities as well as at cell bodies. According to their charge integrals, events were grouped into two populations. The majority (approximately 40 fC) were compatible with full exocytotic fusion of small clear and dense core vesicles shown in previous morphometric studies. The quantal size distribution was modulated by treatment with reserpine and amitriptyline. In addition, much larger quantal events (>1 pC) occurred at predominantly axonal release sites. The time course of signals was severalfold faster than in adrenal chromaffin cells, suggesting profound differences in the release machinery between these cell types. Tetrodotoxin eliminated the majority of events, indicating that release was partially, but not entirely, action potential driven. In conclusion, central norepinephrine release has unique characteristics, distinguishing it from those of other monoaminergic cells in periphery and brain.
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Affiliation(s)
- Zohreh Chiti
- Department of Pharmacology, School of Medical Sciences, Bristol Heart Institute, University of Bristol, University Walk, Bristol BS8 1TD, UK
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79
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Abstract
Magnocellular vasopressin neurones generate distinctive 'phasic' patterns of electrical activity during which periods of spiking activity (bursts) alternate with periods of no spikes or occasional spikes. The mechanisms of burst termination in vivo are still not clearly understood. We recorded from single phasic vasopressin cells in vivo and here we show that burst terminations in some phasic cells is preceded by transient increases in activity, consistent with bursts ending as a result of activity-dependent inhibition. We show that extrinsically imposed increases in activity, evoked by brief stimulation of the organum vasculosum of the lamina terminalis, can either trigger bursts if given when a cell is silent, or stop bursts if given when a cell is active. Thus, the magnocellular vasopressin system is a population of independent bistable oscillators. The population as a whole is insensitive to transient changes in input level, whether these are excitatory or inhibitory. The vasopressin cell population thus acts like a 'low-pass filter'; although brief large changes in input rate have little overall effect, the population responds very effectively to small, sustained changes in input rate by evolving a pattern of discharge activity that efficiently maintains secretion. We note that these filtering characteristics are the opposite of the filtering characteristics that are typically associated with neurones.
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Affiliation(s)
- N Sabatier
- Centre for Integrative Physiology, University of Edinburgh College of Medical and Veterinary Sciences, Edinburgh, UK
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80
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Affiliation(s)
- Michael J McKinley
- Robin M. McAllen, Howard Florey Institute, University of Melbourne, Melbourne, Victoria 3010, Australia
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81
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Urban JH, Leitermann RJ, DeJoseph MR, Somponpun SJ, Wolak ML, Sladek CD. Influence of dehydration on the expression of neuropeptide Y Y1 receptors in hypothalamic magnocellular neurons. Endocrinology 2006; 147:4122-31. [PMID: 16728491 DOI: 10.1210/en.2006-0377] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Regulation of vasopressin (VP) and oxytocin (OT) secretion involves integration of neural signals from hypothalamic osmoreceptors, ascending catecholaminergic and peptidergic cell groups in the brain stem, and local and autoregulatory afferents. Neuropeptide Y (NPY) is one factor that stimulates the release of VP and OT from the supraoptic (SON) and paraventricular nuclei of the hypothalamus via activation of Y1 receptors (Y1R). The current studies were designed to assess the regulation and distribution of NPY Y1R expression in the SON of male rats that were either given 2% NaCl drinking water (24-72 h) or water deprived (48 h). Subjecting male rats to these conditions resulted in significant increases in both the number of cells expressing Y1R immunoreactivity (ir) and the amount of Y1R protein per cell within the SON. Y1R immunoreactivity was increased in the magnocellular but not medial parvocellular paraventricular nuclei, and Y1R mRNA levels were increased in the SON of salt-loaded rats. Subpopulations of both VP and OT cells in the hypothalamus express Y1R immunoreactivity and a greater percentage of VP-ir cells express Y1R after salt loading. To control for potential effects of dehydration-induced anorexia, a group of euhydrate animals was pair fed with animals consuming 2% NaCl. No detectable change in Y1R expression was observed in the SON of pair-fed animals, even though body weights were significantly lower than controls. These data demonstrate that NPY Y1R gene and protein expression are increased in the SON of salt-loaded and water-deprived animals and provide a mechanism whereby NPY can support VP/OT release during prolonged challenges to fluid homeostasis.
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Affiliation(s)
- Janice H Urban
- Department of Physiology and Biophysics, The Chicago Medical School, Rosalind Franklin University of Medicine and Science, 3333 Green Bay Road, North Chicago, Illinois 60064, USA.
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82
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Leng G, Ludwig M. Jacques Benoit Lecture. Information processing in the hypothalamus: peptides and analogue computation. J Neuroendocrinol 2006; 18:379-92. [PMID: 16684129 DOI: 10.1111/j.1365-2826.2006.01428.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Peptides in the hypothalamus are not like conventional neurotransmitters; their release is not particularly associated with synapses, and their long half-lives mean that they can diffuse to distant targets. Peptides can act on their cells of origin to facilitate the development of patterned electrical activity, they can act on their neighbours to bind the collective activity of a neural population into a coherent signalling entity, and the co-ordinated population output can transmit waves of peptide secretion that act as a patterned hormonal analogue signal within the brain. At their distant targets, peptides can re-programme neural networks, by effects on gene expression, synaptogenesis, and by functionally rewiring connections by priming activity-dependent release.
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Affiliation(s)
- G Leng
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, UK.
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83
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Callewaere C, Banisadr G, Desarménien MG, Mechighel P, Kitabgi P, Rostène WH, Mélik Parsadaniantz S. The chemokine SDF-1/CXCL12 modulates the firing pattern of vasopressin neurons and counteracts induced vasopressin release through CXCR4. Proc Natl Acad Sci U S A 2006; 103:8221-6. [PMID: 16702540 PMCID: PMC1570101 DOI: 10.1073/pnas.0602620103] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2005] [Indexed: 11/18/2022] Open
Abstract
Chemokines play a key role in inflammation. They are expressed not only in neuroinflammatory conditions, but also constitutively by different cell types, including neurons in the normal brain, suggesting that they may act as modulators of neuronal functions. Here, we investigated a possible neuroendocrine role of the chemokine stromal cell-derived factor 1 (SDF-1)/CXCL12. We demonstrated the colocalization of SDF-1 and its receptor CXCR4 with arginine vasopressin (AVP) in the magnocellular neurons of the supraoptic nucleus (SON) and the paraventricular hypothalamic nucleus and on AVP projections to the neurohypophysis. Electrophysiological recordings of SON neurons demonstrated that SDF-1 affects the electrical activity of AVP neurons through CXCR4, resulting in changes in AVP release. We observed that SDF-1 can blunt the autoregulation of AVP release in vitro and counteract angiotensin II-induced plasma AVP release in vivo. Furthermore, a short-term physiological increase in AVP release induced by enhanced plasma osmolarity, which was produced by the administration of 1 M NaCl i.p., was similarly blocked by central injection of SDF-1 through CXCR4. A change in water balance by long-term salt loading induced a decrease in both SDF-1 and CXCR4 parallel to that of AVP immunostaining in SON. From these data, we demonstrate that chemokine actions in the brain are not restricted to inflammatory processes. We propose to add to the known autoregulation of AVP on its own neurons, a second autocrine system induced by SDF-1 able to modulate central AVP neuronal activity and release.
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Affiliation(s)
- Céline Callewaere
- *Institut National de la Santé et de la Recherche Médicale, Unité 732, F-75012 Paris, France
- Université Pierre et Marie Curie-Paris 6, Hôpital Saint-Antoine, 184 Rue du Faubourg Saint-Antoine, F-75571 Paris Cedex 12, France
| | - Ghazal Banisadr
- *Institut National de la Santé et de la Recherche Médicale, Unité 732, F-75012 Paris, France
- Université Pierre et Marie Curie-Paris 6, Hôpital Saint-Antoine, 184 Rue du Faubourg Saint-Antoine, F-75571 Paris Cedex 12, France
| | - Michel G. Desarménien
- Institut de Génomique Fonctionnelle, Université Montpellier, Faculté de Médecine, F-34094 Montepellier, France
- Institut National de la Santé et de la Recherche Médicale, Unité 661, F-34094 Montpellier, France; and
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5203, F-34094 Montpellier, France
| | - Patricia Mechighel
- *Institut National de la Santé et de la Recherche Médicale, Unité 732, F-75012 Paris, France
- Université Pierre et Marie Curie-Paris 6, Hôpital Saint-Antoine, 184 Rue du Faubourg Saint-Antoine, F-75571 Paris Cedex 12, France
| | - Patrick Kitabgi
- *Institut National de la Santé et de la Recherche Médicale, Unité 732, F-75012 Paris, France
- Université Pierre et Marie Curie-Paris 6, Hôpital Saint-Antoine, 184 Rue du Faubourg Saint-Antoine, F-75571 Paris Cedex 12, France
| | - William H. Rostène
- *Institut National de la Santé et de la Recherche Médicale, Unité 732, F-75012 Paris, France
- Université Pierre et Marie Curie-Paris 6, Hôpital Saint-Antoine, 184 Rue du Faubourg Saint-Antoine, F-75571 Paris Cedex 12, France
| | - Stéphane Mélik Parsadaniantz
- *Institut National de la Santé et de la Recherche Médicale, Unité 732, F-75012 Paris, France
- Université Pierre et Marie Curie-Paris 6, Hôpital Saint-Antoine, 184 Rue du Faubourg Saint-Antoine, F-75571 Paris Cedex 12, France
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84
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Bacová Z, Kiss A, Jamal B, Payer J, Strbák V. The Effect of Swelling on TRH and Oxytocin Secretion From Hypothalamic Structures. Cell Mol Neurobiol 2006; 26:1047-55. [PMID: 16625432 DOI: 10.1007/s10571-006-9013-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2005] [Accepted: 01/24/2006] [Indexed: 02/02/2023]
Abstract
1. Cell swelling induces exocytosis of material stored in secretory vesicles resulting in a secretory burst of peptidic hormones or enzymes from various types of cells including endocrine cells and neurons. We have previously shown that swelling-induced exocytosis possesses limited selectivity; hypotonic medium evokes TRH but not oxytocin release from hypothalamic paraventricular nucleus (PVN) and neurohypophysis (NH). 2. It is the aim of this study to ascertain whether the swelling-induced oxytocin secretion could be unmasked by the inhibition of specific osmotic response using Ca(2+)-free medium and GdCl(3), an inhibitor of stretch activated channels. 3. Oxytocin release from the PVN was stimulated by the hypotonic medium only in the presence of 50 or 100 microM GdCl(3.) Oxytocin release from supraoptic nucleus (SON) was also stimulated by the Ca(2+)-free hypotonic medium in the presence of GdCl(3). Oxytocin secretion from the NH was not stimulated even in the presence of GdCl(3), both in Ca(2+) containing and Ca(2+)-free medium. TRH response to swelling-inducing stimulus was not affected by the presence of GdCl(3). 4. An intranuclear oxytocin secretion to hyposmotic stimulation within the PVN and the SON could be unmasked by the inhibiting specific response by GdCl(3). At these conditions general secretory response to swelling-inducing stimuli emerged. Secretion of oxytocin from the NH was not affected by any of these treatments. 5. Peptides and proteins released after cell swelling can play an important role in the pathophysiology of ischemia and could be mediators of local or remote preconditioning. Disruption of mechanosensitive gating in magnocellular neurosecretory cells could result in an inadequate secretory response (e.g. stimulation instead of inhibition and vice versa) of hormones engaged in water and salt metabolism regulation.
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Affiliation(s)
- Z Bacová
- Institute of Experimental Endocrinology, Slovak Academy of Sciences, Vlárska 3, Bratislava, Bratislava, 833 06, Slovakia
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Abstract
Neuropeptides that are released from dendrites, such as oxytocin and vasopressin, function as autocrine or paracrine signals at their site of origin, but can also act at distant brain targets to evoke long-lasting changes in behaviour. Oxytocin, for instance, has profound effects on social bonding that are exerted at sites that richly express oxytocin receptors, but which are innervated by few, if any, oxytocin-containing projections. How can a prolonged, diffuse signal have coherent behavioural consequences? The recently demonstrated ability of neuropeptides to prime vesicle stores for activity-dependent release could lead to a temporary functional reorganization of neuronal networks harbouring specific peptide receptors, providing a substrate for long-lasting effects.
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Affiliation(s)
- Mike Ludwig
- Laboratory of Neuroendocrinology, Centre for Integrative Physiology, University of Edinburgh, George Square, Edinburgh EH8 9XD, UK.
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Zhang Z, Bourque CW. Calcium permeability and flux through osmosensory transduction channels of isolated rat supraoptic nucleus neurons. Eur J Neurosci 2006; 23:1491-500. [PMID: 16553612 DOI: 10.1111/j.1460-9568.2006.04670.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Hypertonic stimuli delivered into the supraoptic nucleus provoke neuropeptide release from the somata of magnocellular neurosecretory cells (MNCs) in the presence of tetrodotoxin, suggesting that such stimuli can increase intracellular calcium concentration ([Ca2+]i) in the absence of action potentials. We therefore examined whether the stretch-inhibited cation (SIC) channels of MNCs can mediate calcium influx. Whole-cell recordings were made in MNCs isolated from the supraoptic nuclei of adult rats. Measurements of reversal potentials in different solutions revealed that the current induced by a suction-evoked decrease in cell volume (ISIC) displays a selectivity sequence for monovalent cations of K+>Cs+>Na+>NMDG+. The permeability of SIC channels to Ca2+, relative to Na+, was approximately 5. In the presence of physiological concentrations of external Na+ and K+, the amplitude of inward ISIC was reduced dose-dependently by external Ca2+ with an IC50 of 4.9 mM. This was not due to reduced suction-evoked volume changes or to an accumulation of [Ca2+]i. Confocal imaging of cytoplasmic Calcium Green-1 fluorescence revealed that activation of ISIC significantly increases [Ca2+]i in physiological solutions. This effect is absent in Ca2+-free solution, or when Gd3+ (300 microM) is added to Ca2+-containing solution. Part of this effect is inhibited in the presence of dantrolene (10 microM) and heparin (4 mg/mL), suggesting that release from intracellular Ca2+ stores participates in suction-evoked Ca2+ signalling. These observations indicate that SIC channels are highly permeable to Ca2+, mediate significant Ca2+ entry and release of Ca2+ from internal stores under conditions when the volume of MNCs is decreased.
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Affiliation(s)
- Zizhen Zhang
- Centre for Research in Neuroscience, Research Institute of the McGill University Health Center, 1650 Cedar Avenue, Montreal, QC, Canada, H3G 1A4
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