Extracellular oxytocin in the paraventricular nucleus: hyperosmotic stimulation by in vivo microdialysis

Hattori, Teruhiko; Morris, Mariana; Alexander, Natalie; Sundberg, David K.

doi:10.1016/0006-8993(90)91216-4

Cited by 58 publications

(34 citation statements)

References 22 publications

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“…Al though we are not able to provide a clear explanation for this observation, the following mechanism might have been operant. That is that the magnocellular neurons in the PVN and also the supraoptic nucleus are capable of releasing neurosecretory granules by exocytosis at vir tually any part of their plasmalemma, such as dendrites, cell bodies, and axon collaterals, not merely the wellknown perivascular nerve endings [44][45][46].…”

Section: Discussionmentioning

confidence: 99%

Intrahypothalamic Perfusion with lnterleukin-1-Beta Stimulates the Local Release of Corticotropin-Releasing Hormone and Arginine Vasopressin and the Plasma Adrenocorticotropin in Freely Moving Rats: A Comparative Perfusion of the Paraventricular Nucleus and the Median Eminence

Watanobe

Takebe

1993

Neuroendocrinology

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It is almost generally accepted that an acute-phase ACTH response induced by interleukin (IL)-1 is mediated principally by CRH release from the hypothalamus. However, the precise cellular site of action of IL-1 in activating the CRH neuronal system remains to be determined. Two likely candidates comprise the paraventricular nucleus (PVN) where CRH neuronal cell bodies are located, and the median eminence (ME) where their nerve endings are terminated. Therefore, in this study we performed a comparative perfusion of the ME and the PVN with increasing concentrations of recombinant human IL-1β utilizing the push-pull perfusion technique in freely moving rats. We measured the plasma ACTH and ME and PVN levels of CRH, and also of AVP, because AVP, another secretagogue of ACTH, has its cell body in the PVN and axon terminals partly in the ME. In control groups, the ME or the PVN was perfused with artificial cerebrospinal fluid between 12:00 and 15:00 h, and perfusates and blood samples were collected every 20 min. In the other groups, either the ME or the PVN was perfused with three increasing concentrations (0.1, 1.0, and 10 nM) of recombinant human IL-1β dissolved in artificial cerebrospinal fluid only between 13:00 and 14:00 h with all the other procedures run in the same way as in the controls. In the control perfusions, the hypothalamic release of CRH and AVP and the plasma ACTH did not change significantly during the entire period of observation. In the ME perfusion with IL-1β, 1.0 and 10 nM, but not 0.1 nM, of the cytokine significantly and dose-dependently stimulated CRH and AVP secretions in the ME and the plasma ACTH. ACTH responses during the PVN perfusion with IL-1β were similar to those during the ME perfusion, except that at the PVN the lowest concentration (0.1 nM) of the cytokine was already effective in stimulating ACTH secretion. These in vivo data suggest that IL-1β may act on both the ME and the PVN to stimulate CRH and,’ thereby, ACTH secretions. The secretory response of hypothalamic AVP to IL-1β, which was similar to that of CRH, suggests that not only CRH but also AVP may mediate the IL-1β stimulation of ACTH secretion.

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Section: Discussionmentioning

confidence: 99%

Intrahypothalamic Perfusion with lnterleukin-1-Beta Stimulates the Local Release of Corticotropin-Releasing Hormone and Arginine Vasopressin and the Plasma Adrenocorticotropin in Freely Moving Rats: A Comparative Perfusion of the Paraventricular Nucleus and the Median Eminence

Watanobe

Takebe

1993

Neuroendocrinology

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“…It is therefore of much interest to know if this general mechanism could posses some specific-ity. It is well established that direct stimulation of the hypothalamic paraventricular and supraoptic nuclei with hyperosmotic saline via microdialysis increases vasopressin and oxytocin levels in extracellular fluid [34][35][36][37] by a mechanism including axons, dendrites and cell bodies [38]. Their level also increases in plasma as a result of their release from axon terminals in the posterior pituitary.…”

Section: +mentioning

confidence: 99%

“…Their level also increases in plasma as a result of their release from axon terminals in the posterior pituitary. These neuropeptides are released within nuclei and into the blood in a Ca 2+ dependent manner [34,39]. In our experiments, we used tissue explants of hypothalamic paraventricular nucleus and posterior pituitary for simultaneous TRH and oxytocin study.…”

Section: +mentioning

confidence: 99%

Cell Volume Induced Hormone Secretion: Studies on Signal Transduction and Specificity

Najvirtova

Greer

et al. 2003

Cell Physiol Biochem

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Cell swelling causes an immediate secretory response in various cell types. Induced secretion possesses some unique features suggesting the involvement of a specific signal transduction pathway. The effect of 10-20 µM GdCl₃, 100 µM HgCl₂, 1-100 µM indomethacin and 1-20 µM nordihydroguaiaretic acid (NDGA) on cell swelling-induced hormone secretion (isosmotic 80 mM ethanol or 15-30% hyposmotic medium) from incubated rat hypothalamic paraventricular nucleus (PVN) and posterior pituitary (oxytocin and TRH), isolated pancreatic islets (TRH) and perifused anterior pituitary cells (prolactin) were examined. To determine how general the effect of cell swelling is on exocytotic secretion, the release of two different neurohormones (thyrotropin releasing hormone -TRH and oxytocin) from the same tissue explant were studied. Both hyposmotic medium or isosmotic ethanol containing medium induced immediate TRH and prolactin release from the tested tissues.The effect of GdCl₃, HgCl₂, NDGA or indomethacin showed no inhibition of cell swelling induced secretion. In contrast to TRH, oxytocin release was not induced by isosmotic ethanol containing medium from the PVN or posterior pituitary. CONCLUSION: These data indicate that signal transduction leading to exocytosis after cell swelling does not involve GdCl₃ sensitive stretch activated channels, mercury sensitive aquaporins, or indomethacin and NDGA sensitive mediators including prostaglandins and leukotriens. Cell swelling-induced exocytosis possesses limited selectivity; cells specifically involved in water and salt regulation retain their specific response to osmotic stimuli.

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“…This peripheral release is accompanied by an intrace rebral release of both nonapeptides from centrally project ing neurons within limbic target regions [3][4][5]. Recently, electron microscopical/immunocytochemical [6] and mi croperfusion studies [7][8][9][10] revealed nonapeptide release within the hypothalamic nuclei themselves, and this in tranuclear release has been shown to respond to suckling [10] as well as to direct osmotic stimulation via microdia lysis [7,8], It is, however, generally poorly understood in which way nonapeptide release into different compart ments is regulated and if, for example, a neuron is capable of releasing OXT or AVP from different areas of its plasmalemma in a coordinated or independent manner. The SON, as a relatively homogenous nucleus with neuronal structures which release both nonapeptides into blood as well as intranuclearly, provides an excellent model to study release patterns into different compartments.…”

Section: Introductionmentioning

confidence: 99%

Simultaneous Microdialysis in Blood and Brain: Oxytocin and Vasopressin Release in Response to Central and Peripheral Osmotic Stimulation and Suckling in the Rat

Ludwig²,

et al. 1993

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Simultaneous microdialysis in blood and brain has been used to monitor the release of both oxytocin and vasopressin into the systemic circulation (jugular vein/right atrium) and within the hypothalamic supraoptic nucleus of rats. Both home-made probes for blood and brain microdialysis revealed detectable nonapeptide concentrations under basal conditions and differential responses to a variety of stimuli. In urethane-anesthetized male rats, bilateral stimulation of the supraoptic nucleus by microdialyzing hypertonic medium (1 M NaCl) not only significantly increased the intranuclear release of both oxytocin and vasopressin (p < 0.05), but also their release from the neurohypophysis into blood (p < 0.05). In poststimulation microdialysates sampled from blood, the nonapeptides reached basal levels again, whereas intranuclear levels were further elevated. Intraperitoneal injection of hypertonic saline, on the other hand, resulted not only in the well-known increased peripheral release of oxytocin and vasopressin (p < 0.01 each), but also in a delayed increase in intranuclear oxytocin (p < 0.05). In contrast, intranuclear vasopressin release failed to change within the 90-min period following osmotic stimulation. In conscious lactating rats, suckling increased oxytocin contents in microdialysates sampled simultaneously in blood and the supraoptic nucleus (p < 0.05 each) further validating the microdialysis techniques used. The in vivo recovery in blood of approximately 65% determined using both radiolabeled and endogenous oxytocin provides a rough estimate to assess nonapeptide concentrations in plasma from 30-min or even 10-min blood microdialysis data. The results of the present study suggest that simultaneous microdialysis in blood and brain provides a useful tool to study patterns of peripheral and central release. Dependent upon the characteristics of the stimulus used, nonapeptide release into the different compartments may be either differentially regulated or coordinated.

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Extracellular oxytocin in the paraventricular nucleus: hyperosmotic stimulation by in vivo microdialysis

Cited by 58 publications

References 22 publications

Intrahypothalamic Perfusion with lnterleukin-1-Beta Stimulates the Local Release of Corticotropin-Releasing Hormone and Arginine Vasopressin and the Plasma Adrenocorticotropin in Freely Moving Rats: A Comparative Perfusion of the Paraventricular Nucleus and the Median Eminence

Intrahypothalamic Perfusion with lnterleukin-1-Beta Stimulates the Local Release of Corticotropin-Releasing Hormone and Arginine Vasopressin and the Plasma Adrenocorticotropin in Freely Moving Rats: A Comparative Perfusion of the Paraventricular Nucleus and the Median Eminence

Cell Volume Induced Hormone Secretion: Studies on Signal Transduction and Specificity

Simultaneous Microdialysis in Blood and Brain: Oxytocin and Vasopressin Release in Response to Central and Peripheral Osmotic Stimulation and Suckling in the Rat

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