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Rüdiger Gerstberger - One of the best experts on this subject based on the ideXlab platform.
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Interleukin-10 modulates the synthesis of inflammatory mediators in the sensory Circumventricular Organs: implications for the regulation of fever and sickness behaviors
Journal of neuroinflammation, 2013Co-Authors: Lois M. Harden, Rüdiger Gerstberger, Christoph Rummel, Giamal N. Luheshi, Stephen Poole, Joachim RothAbstract:Background Whereas the role played by interleukin (IL)-10 in modulating fever and sickness behavior has been linked to it targeting the production of pro-inflammatory cytokines in the circulation, liver and spleen, it is not known whether it could directly target the local production of pro-inflammatory cytokines within the sensory Circumventricular Organs (CVOs) situated within the brain, but outside the blood–brain barrier. Using inactivation of IL-10, we, therefore, investigated whether IL-10 could modulate the synthesis of pro-inflammatory cytokines within the sensory CVOs, in particular the organum vasculosum laminae terminalis (OVLT) and area postrema (AP).
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Signaling the brain in systemic inflammation: role of sensory Circumventricular Organs.
Frontiers in bioscience : a journal and virtual library, 2004Co-Authors: Joachim Roth, Rüdiger Gerstberger, Eva-maria Harré, Christoph Rummel, Thomas HübschleAbstract:The sensory Circumventricular Organs (CVOs) are specialized brain regions that lack a tight blood-brain barrier. A role for these brain structures in signaling the brain during systemic inflammation is based on the following sets of observations. In spite of some conflicting data from literature, lesions of CVOs have been shown to block several components of brain controlled illness responses (i.e. fever or neuroendocrine modifications). Receptors for inflammatory cytokines and for bacterial fragments are constitutively expressed in cells within the sensory CVOs. The expression of most of these receptors is upregulated under conditions of systemic inflammation. Cellular responses in theses brain areas can be recorded and documented after stimulation of these respective receptors. Such responses include changes in electrical activity of neurons, induction of transcription factors leading to modifications in gene expression during inflammation and to a localized release of secondary signal molecules. These molecules may influence or even gain access to neural structures inside the blood-brain barrier, which can normally not directly be reached by circulating cytokines or bacterial fragments.
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Astrocytes in sensory Circumventricular Organs of the rat brain express functional binding sites for endothelin
Neuroscience, 2000Co-Authors: E Gebke, Andreas Müller, Ulrich Pehl, Rüdiger GerstbergerAbstract:Abstract Sensory Circumventricular Organs bordering the anterior third cerebral ventricle, the subfornical organ and the organum vasculosum laminae terminalis, lack blood–brain barrier characteristics and are therefore accessible to circulating peptides like endothelins. Astrocytes of the rat subfornical organ and organum vasculosum laminae terminalis additionally showed immunocytochemical localization of endothelin-1/endothelin-3-like peptides, possibly acting as Circumventricular organ-intrinsic modulators. Employing [ 125 I]endothelin-1 as radioligand, quantitative autoradiography demonstrated specific binding sites throughout the rat organum vasculosum laminae terminalis and subfornical organ, and competitive displacement studies revealed expression of both ET A and ET B receptor subtypes for either Circumventricular organ. ET B receptor binding prevailed for the whole brain and ET A receptors could be labelled in the peripheral vascular system. To characterize endothelin-specific receptors in astrocytes of both Circumventricular Organs, alterations in the intracellular calcium concentration due to endothelin-1/endothelin-3 stimulation were studied in primary culture of subfornical organ and organum vasculosum laminae terminalis cells obtained from early postnatal rat pups. Endothelin-1 and endothelin-3 induced Ca 2+ transients in 9–13% of either subfornical organ or organum vasculosum laminae terminalis astrocytes, respectively, and some glial cells (subfornical organ: 2%, organum vasculosum laminae terminalis: 5%) responded to both endothelin analogues. The antagonistic action of BQ123 specific for ET A receptors (74% of all astrocytes tested), and the pronounced responsiveness to the ET B receptor agonist [4Ala]ET-1 (subfornical organ: 27%, organum vasculosum laminae terminalis: 35%) demonstrated glial expression of both endothelin receptor subtypes. Agonist-induced elevations in the intracellular calcium concentration proved to be independent of extracellular Ca 2+ . In summary, the results indicate that endothelin(s) interact(s) with Circumventricular organ astrocytes. Competitive receptor binding techniques using brain tissue sections as well as a fura-2 loaded primary cell culture system of the subfornical organ and organum vasculosum laminae terminalis demonstrate glial expression of functional ET A and ET B receptors, with calcium as intracellular messenger emerging primarily from intracellular stores. Endothelin(s) of both circulating and Circumventricular organ-intrinsic origin may afferently transfer information important for cardiovascular homeostasis to Circumventricular Organs serving as “windows to the brain”.
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Angiotensin II-induced calcium signalling in neurons and astrocytes of rat Circumventricular Organs
Neuroscience, 1998Co-Authors: E Gebke, Andreas Müller, Mirek Jurzak, Rüdiger GerstbergerAbstract:Abstract The subfornical organ and organum vasculosum laminae terminalis represent neuroglial Circumventricular organ structures bordering the anterior third cerebral ventricle. Owing to the absence of the blood–brain barrier, the cellular elements of the subfornical organ and the organum vasculosum laminae terminalis can be reached by circulating messenger molecules transferring afferent information. As demonstrated for the control of extracellular fluid composition, the circulating hormone angiotensin II acts on these sensory Circumventricular Organs to induce drinking, elevated peripheral resistance and neurohypophyseal hormone release via interaction with membrane-spanning receptor proteins. To characterize the cell-specific distribution of angiotensin II receptors within the Circumventricular Organs, primary cell cultures derived from the subfornical organ or organum vasculosum laminae terminalis of five- to six-day-old rat pups were used to measure alterations in intracellular calcium at the single cell level. Neurons and astrocytes were identified by immunocytochemical staining for specific marker proteins. Bath application of angiotensin II (10 −10 –10 −6 M) dose-dependently induced calcium transients in neurons (19.6%) and astrocytes (15.7%), and angiotensin II threshold concentrations to elicit intracellular calcium signalling proved to be one order of magnitude higher in astrocytes as compared to neurons (10 −9 M). At angiotensin II concentrations higher than 10 −7 M, pronounced desensitization of the angiotensin II receptor occurred. Employing the angiotensin II receptor antagonists losartan (DUP-753; AT 1 -receptor) and PD-123319 (AT 2 -receptor), exclusive expression of the AT 1 receptor subtype coupled to intracellular calcium concentration signalling could be demonstrated for neurons and astrocytes. In all cells examined, the angiotensin II-evoked increase in intracellular calcium concentrations could be fully suppressed in the absence of extracellular calcium. Co-activation by angiotensin II and other agents (vasopressin, its fragment 8-arginine-vasopressin (4–9) , oxytocin, endothelin) was indicated for subfornical organ neurons and organum vasculosum laminae terminalis astrocytes.
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AVP-fragment peptides induce Ca2+ transients in cells cultured from rat Circumventricular Organs.
Brain research, 1995Co-Authors: Mirek Jurzak, Andreas Müller, Rüdiger GerstbergerAbstract:To investigate receptors for the naturally occurring fragments of [Arg8]vasoperssin (AVP), Ca2+ measurements were performed in cells cultured from the subfornical organ (SFO) and the organum vasculosum of the lamina terminalis (OVLT). AVP(4–9) and AVP(4–8) applied in nanomolar concentrations triggered rises in the intracellular Ca2+ concentration in neurons and astrocytes cultured from both Circumventricular Organs (CVOs) which are located in the lamina terminalis of the rat brain. The determination of the investigated cell type was confirmed by immunocytochemistry with cell type-specific antibodies. The functional data from single cultured cells and receptor autoradiographic studies on tissue slices favour the existence of specific receptors for AVP fragments which are different from those for the paternal AVP.
Yasuyuki Yamashita - One of the best experts on this subject based on the ideXlab platform.
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Circumventricular Organs of human brain visualized on post-contrast 3D fluid-attenuated inversion recovery imaging
Neuroradiology, 2018Co-Authors: Minako Azuma, Toshinori Hirai, Yoshihito Kadota, Zaw Aung Khant, Yohei Hattori, Mika Kitajima, Hiroyuki Uetani, Yasuyuki YamashitaAbstract:Purpose Although contrast-enhanced three-dimensional T2 fluid-attenuated inversion recovery (3D T2-FLAIR) images are useful for assessing various neuronal diseases, physiological enhancement of the Circumventricular Organs on the images have not been investigated. We aimed to assess the physiological appearance of the Circumventricular Organs on contrast-enhanced 3D T2-FLAIR images. Methods We studied 3-T MR images of the brain of 30 individuals with no apparent brain abnormalities. In ten areas of the brain, the degree of contrast enhancement on 3D T2-FLAIR and magnetization-prepared rapid gradient-echo (MPRAGE) images was evaluated using a 4-point grading system. The pre- and post-contrast mean contrast ratios (CRs) of the anterior pituitary gland, median eminence, and pineal gland were compared. Results On post-contrast 3D T2-FLAIR images, marked enhancement was most frequently scored in the median eminence, followed by the choroid plexus, posterior pituitary gland, and pineal gland. In 10 of the 30 cases, the vascular organ of the lamina terminalis and the area postrema were enhanced but the subcommissural organ was not. The difference in the mean pre- and post-contrast CRs of the median eminence and pineal gland was statistically significant, while that of the anterior pituitary gland was not. Conclusion On contrast-enhanced 3D T2-FLAIR images, the Circumventricular Organs show variable enhancement. Our findings help to recognize physiological and abnormal enhancement of brain structures on contrast-enhanced 3D T2-FLAIR images.
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Circumventricular Organs of human brain visualized on post-contrast 3D fluid-attenuated inversion recovery imaging.
Neuroradiology, 2018Co-Authors: Minako Azuma, Toshinori Hirai, Yoshihito Kadota, Zaw Aung Khant, Yohei Hattori, Mika Kitajima, Hiroyuki Uetani, Yasuyuki YamashitaAbstract:Although contrast-enhanced three-dimensional T2 fluid-attenuated inversion recovery (3D T2-FLAIR) images are useful for assessing various neuronal diseases, physiological enhancement of the Circumventricular Organs on the images have not been investigated. We aimed to assess the physiological appearance of the Circumventricular Organs on contrast-enhanced 3D T2-FLAIR images. We studied 3-T MR images of the brain of 30 individuals with no apparent brain abnormalities. In ten areas of the brain, the degree of contrast enhancement on 3D T2-FLAIR and magnetization-prepared rapid gradient-echo (MPRAGE) images was evaluated using a 4-point grading system. The pre- and post-contrast mean contrast ratios (CRs) of the anterior pituitary gland, median eminence, and pineal gland were compared. On post-contrast 3D T2-FLAIR images, marked enhancement was most frequently scored in the median eminence, followed by the choroid plexus, posterior pituitary gland, and pineal gland. In 10 of the 30 cases, the vascular organ of the lamina terminalis and the area postrema were enhanced but the subcommissural organ was not. The difference in the mean pre- and post-contrast CRs of the median eminence and pineal gland was statistically significant, while that of the anterior pituitary gland was not. On contrast-enhanced 3D T2-FLAIR images, the Circumventricular Organs show variable enhancement. Our findings help to recognize physiological and abnormal enhancement of brain structures on contrast-enhanced 3D T2-FLAIR images.
A.v. Ferguson - One of the best experts on this subject based on the ideXlab platform.
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Fluid/Mineral Balance: The Circumventricular Organs
Reference Module in Neuroscience and Biobehavioral Psychology, 2017Co-Authors: W.m. Fry, A.v. FergusonAbstract:The Circumventricular Organs (CVOs) of the brain are a unique group of structures that lack the normal blood-brain-barrier and are thus in the privileged position of either being able to sample the total contents of the systemic circulation (sensory CVOs) or being able to secrete substances directly into the circulation (secretory CVOs). Neurons in the sensory CVOs are ideally positioned at the blood-brain interface to monitor major constituents of body fluids. They have been shown to sense circulating concentrations of angiotensin II, sodium, calcium as well as osmolality, and they control a variety of autonomic outputs through efferent projections to essential hypothalamic and medullary autonomic control centers. The secretory CVOs, in contrast, play important roles in the secretion of many of the neurohormones produced in the hypothalamus which play essential roles in the regulation of body fluid balance. Collectively, these structures are now recognized to play important integrative roles in the regulation of fluid and mineral balance.
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Regulation of Nervous System Function by Circumventricular Organs
Neuroimmune Pharmacology, 2016Co-Authors: Emily A. E. Black, Nicole M. Cancelliere, A.v. FergusonAbstract:In this chapter, we highlight the specialized features of the sensory Circumventricular Organs (CVO) as central nervous system (CNS) structures located at the blood-brain interface. These structures appear to play critical roles in sensing and integrating information regarding autonomic status derived from circulating signals that do not readily cross the BBB. Intriguingly, while the majority of the original literature highlighting such roles attributed primarily fluid balance and cardiovascular functions to the subfornical organ (SFO) and metabolic function to the area postrema (AP), more recent work as highlighted in this chapter has clearly demonstrated, not only overlap in these physiological roles in SFO and AP, but also additional roles for these CVOs in reproductive and of primary importance to this chapter immune signaling from the circulation to the CNS. Within not only SFO and AP, but also the organum vasculosum of the lamina terminalis, the emerging literature supports the conclusion that single neurons in these CVOs sense, and presumably integrate, signals related to all of these separately classified autonomic functions. In recognizing the potential for such integration in the sensory CVOs, it becomes important to also understand that optimal health is associated with the ability of our physiological systems to regulate these functions in an integrated rather than separate manner.
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Circumventricular Organs: targets for integration of circulating fluid and energy balance signals?
Physiology & behavior, 2013Co-Authors: Andrea Mimee, Pauline M. Smith, A.v. FergusonAbstract:The subfornical organ (SFO), as one of the sensory Circumventricular Organs (CVOs), is among the only central nervous system structures which interfaces directly with circulating substances that do not cross the blood brain barrier. Here we describe a growing literature showing that circulating indicators of cardiovascular (angiotensin II, osmolarity, calcium, sodium) and metabolic (adiponectin, amylin, glucose, ghrelin, leptin) statuses influence the excitability of single SFO neurons. Single cell electrophysiological studies from our laboratory have demonstrated excitatory effects of angiotensin II on individual SFO neurons, and changes in angiotensin II receptor expression in this CVO in hypertensive states emphasize the dynamic contribution of SFO neurons to the regulation of fluid balance. Furthermore, we have shown both depolarizing and hyperpolarizing effects of the adipokines adiponectin and leptin in SFO cells, and highlight that conditions of fasting in the case of adiponectin, and obesity in the case of leptin, alter the sensitivity of SFO neurons to these circulating factors. The results examined in this review provide evidence for a role of the SFO as a mediator and integrative structure in the maintenance of cardiovascular and metabolic functions.
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The sensory Circumventricular Organs: brain targets for circulating signals controlling ingestive behavior.
Physiology & behavior, 2007Co-Authors: Mark Fry, A.v. FergusonAbstract:Sensory Circumventricular Organs (CVOs) are specialized areas of the brain that lack a normal blood-brain barrier, and therefore are in constant contact with signaling molecules circulating in the bloodstream. Neurons of the CVOs are well endowed with a wide spectrum of receptors for hormones and other signaling molecules, and they have strong connections to hypothalamic and brainstem nuclei. Therefore, lying at the blood-brain interface, the sensory CVOs are in a unique position of being able to detect and integrate humoral and neural information and relay the resulting signals to autonomic control centers of the hypothalamus and medulla. This review focuses primarily on the roles played by the sensory CVOs in fluid balance and energy metabolism.
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Making sense of it: roles of the sensory Circumventricular Organs in feeding and regulation of energy homeostasis.
Experimental biology and medicine (Maywood N.J.), 2007Co-Authors: Mark Fry, Ted D. Hoyda, A.v. FergusonAbstract:Obesity is associated with significant health risks including stroke and heart disease. The prevalence of obesity has dramatically increased over the past 20 years. Although the development of obesity is clearly related to changing lifestyles, the central nervous system plays a key role in regulation of energy balance. To develop effective strategies for treating obesity, we must gain a clearer understanding of the neuro-circuitry and signaling mechanisms involved. Toward this end, recent progress has been made in the understanding of the roles played by the sensory Circumventricular Organs (CVOs) of the brain. These areas lack the normal blood-brain barrier and thus act as transducers of signals between the blood, other centers in the brain, and the cerebrospinal fluid. This review focuses on the roles played by the sensory CVOs in detecting and responding to a number of signals that carry information regarding nutritional status, including cholecystokinin, amylin, ghrelin, peptide YY, pancreatic polypep...
Naotoshi Murakami - One of the best experts on this subject based on the ideXlab platform.
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suppression of interleukin 1β production in the Circumventricular Organs in endotoxin tolerant rabbits
Brain Research, 1995Co-Authors: T Nakamori, Yoshiyuki Sakata, T Watanabe, Akio Morimoto, Shoji Nakamura, Naotoshi MurakamiAbstract:Interleukin-1 beta (IL-1 beta) production in the brain and the spleen was investigated in rabbits which show febrile tolerance to bacterial endotoxin, lipopolysaccharide (LPS). Febrile tolerance to LPS was induced by daily intravenous (i.v.) injections of LPS (4 micrograms/kg, i.v.) for 5 days. In the LPS-tolerant rabbits, the second phase of the biphasic fever induced by i.v. injection of LPS (4 micrograms/kg) disappeared, although the first phase remained intact. In situ hybridization and immunohistochemical studies revealed that IL-1 beta production was observed in the Circumventricular Organs, such as the organum vasculosum laminae terminalis (OVLT), subfornical organ (SFO) and area posterema (AP), 1 h after the first exposure to i.v. injection of LPS (4 micrograms/kg) (acute rabbits). In contrast, IL-1 beta production in these Circumventricular Organs disappeared in the LPS-tolerant rabbits. IL-1 beta production was observed in the spleens of the acute and the LPS-tolerant rabbits after i.v. injections of LPS. The cells which produced IL-1 beta in the spleen following LPS injections were confirmed to be monocytes/macrophages and polymorphonuclear leukocytes by immunohistochemistry in both the acute and the LPS-tolerant rabbits. The LPS-injected acute rabbits showed a significant increase in the number of IL-1 beta-immunoreactive monocytes/macrophages, compared with that in the saline-injected acute rabbits. However, there was no significant difference in immunoreactive cell numbers between the saline-injected acute and LPS-injected tolerant rabbits, or between the LPS-injected acute and the LPS-injected tolerant rabbits.(ABSTRACT TRUNCATED AT 250 WORDS)
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Suppression of interleukin-1β production in the Circumventricular Organs in endotoxin-tolerant rabbits
Brain Research, 1995Co-Authors: T Nakamori, Yoshiyuki Sakata, T Watanabe, Akio Morimoto, Shoji Nakamura, Naotoshi MurakamiAbstract:Abstract Interleukin-1β (IL-1β) production in the brain and the spleen was investigated in rabbits which show febrile tolerance to bacterial endotoxin, lipopolysaccharide (LPS). Febrile tolerance to LPS was induced by daily intravenous (i.v.) injections of LPS (4 μg/kg, i.v.) for 5 days. In the LPS-tolerant rabbits, the second phase of the biphasic fever induced by i.v. injection of LPS (4 μg/kg) disappeared, although the first phase remained intact. In situ hybridization and immunohistochemical studies revealed that IL-1β production was observed in the Circumventricular Organs, such as the organum vasculosum laminae terminalis (OVLT), subfornical organ (SFO) and area posterema (AP), 1 h after the first exposure to i.v. injection of LPS (4 μg/kg) (acute rabbits). In contrast, IL-1β production in these Circumventricular Organs disappeared in the LPS-tolerant rabbits. IL-1β production was observed in the spleens of the acute and the LPS-tolerant rabbits after i.v. injections of LPS. The cells which produced IL-1β in the spleen following LPS injections were confirmed to be monocytes/macrophages and polymorphonuclear leukocytes by immunohistochemistry in both the acute and the LPS-tolerant rabbits. The LPS-injected acute rabbits showed a significant increase in the number of IL-1β-immunoreactive monocytes/macrophages, compared with that in the saline-injected acute rabbits. However, there was no significant difference in immunoreactive cell numbers between the saline-injected acute and LPS-injected tolerant rabbits, or between the LPS-injected acute and the LPS-injected tolerant rabbits. These results suggest that the observed change in IL-1β production may be responsible for the disappearance of the second phase of the biphasic fever induced by repeated injections of LPS.
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Suppression of interleukin-1 beta production in the Circumventricular Organs in endotoxin-tolerant rabbits.
Brain research, 1995Co-Authors: T Nakamori, Yoshiyuki Sakata, T Watanabe, Akio Morimoto, Shoji Nakamura, Naotoshi MurakamiAbstract:Interleukin-1 beta (IL-1 beta) production in the brain and the spleen was investigated in rabbits which show febrile tolerance to bacterial endotoxin, lipopolysaccharide (LPS). Febrile tolerance to LPS was induced by daily intravenous (i.v.) injections of LPS (4 micrograms/kg, i.v.) for 5 days. In the LPS-tolerant rabbits, the second phase of the biphasic fever induced by i.v. injection of LPS (4 micrograms/kg) disappeared, although the first phase remained intact. In situ hybridization and immunohistochemical studies revealed that IL-1 beta production was observed in the Circumventricular Organs, such as the organum vasculosum laminae terminalis (OVLT), subfornical organ (SFO) and area posterema (AP), 1 h after the first exposure to i.v. injection of LPS (4 micrograms/kg) (acute rabbits). In contrast, IL-1 beta production in these Circumventricular Organs disappeared in the LPS-tolerant rabbits. IL-1 beta production was observed in the spleens of the acute and the LPS-tolerant rabbits after i.v. injections of LPS. The cells which produced IL-1 beta in the spleen following LPS injections were confirmed to be monocytes/macrophages and polymorphonuclear leukocytes by immunohistochemistry in both the acute and the LPS-tolerant rabbits. The LPS-injected acute rabbits showed a significant increase in the number of IL-1 beta-immunoreactive monocytes/macrophages, compared with that in the saline-injected acute rabbits. However, there was no significant difference in immunoreactive cell numbers between the saline-injected acute and LPS-injected tolerant rabbits, or between the LPS-injected acute and the LPS-injected tolerant rabbits.(ABSTRACT TRUNCATED AT 250 WORDS)
Mirek Jurzak - One of the best experts on this subject based on the ideXlab platform.
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Angiotensin II-induced calcium signalling in neurons and astrocytes of rat Circumventricular Organs
Neuroscience, 1998Co-Authors: E Gebke, Andreas Müller, Mirek Jurzak, Rüdiger GerstbergerAbstract:Abstract The subfornical organ and organum vasculosum laminae terminalis represent neuroglial Circumventricular organ structures bordering the anterior third cerebral ventricle. Owing to the absence of the blood–brain barrier, the cellular elements of the subfornical organ and the organum vasculosum laminae terminalis can be reached by circulating messenger molecules transferring afferent information. As demonstrated for the control of extracellular fluid composition, the circulating hormone angiotensin II acts on these sensory Circumventricular Organs to induce drinking, elevated peripheral resistance and neurohypophyseal hormone release via interaction with membrane-spanning receptor proteins. To characterize the cell-specific distribution of angiotensin II receptors within the Circumventricular Organs, primary cell cultures derived from the subfornical organ or organum vasculosum laminae terminalis of five- to six-day-old rat pups were used to measure alterations in intracellular calcium at the single cell level. Neurons and astrocytes were identified by immunocytochemical staining for specific marker proteins. Bath application of angiotensin II (10 −10 –10 −6 M) dose-dependently induced calcium transients in neurons (19.6%) and astrocytes (15.7%), and angiotensin II threshold concentrations to elicit intracellular calcium signalling proved to be one order of magnitude higher in astrocytes as compared to neurons (10 −9 M). At angiotensin II concentrations higher than 10 −7 M, pronounced desensitization of the angiotensin II receptor occurred. Employing the angiotensin II receptor antagonists losartan (DUP-753; AT 1 -receptor) and PD-123319 (AT 2 -receptor), exclusive expression of the AT 1 receptor subtype coupled to intracellular calcium concentration signalling could be demonstrated for neurons and astrocytes. In all cells examined, the angiotensin II-evoked increase in intracellular calcium concentrations could be fully suppressed in the absence of extracellular calcium. Co-activation by angiotensin II and other agents (vasopressin, its fragment 8-arginine-vasopressin (4–9) , oxytocin, endothelin) was indicated for subfornical organ neurons and organum vasculosum laminae terminalis astrocytes.
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Vasopressin and sensory Circumventricular Organs.
Progress in brain research, 1998Co-Authors: Mirek Jurzak, Herbert A. SchmidAbstract:Abstract The subfornical organ, the area postrema and the organum vasculosum of the lamina terminalis are considered to be sensory Circumventricular Organs as they contain neuronal somata which are located outside the blood-brain barrier and are thus capable of serving as ‘sensors’ for blood-borne humoral messengers. The endocrine hormone, vasopresssin (VP), not only causes strong antidiuresis by acting on the kidney, but also exerts centrally mediated effects as a neuromodulator. Several lines of evidence suggest that VP can influence regulatory functions mediated by the sensory Circumventricular Organs, since vasopresssinergic somata and terminals as well as VP receptors have been reposted to be present in these structures. These biochemical prerequisites offer the possibility that blood-borne VP might on the one hand act as a feedback signal from the periphery and, on the other hand, synap-tically released or locally produced VP could modulate the known functions of sensory Circumventricular Organs, such as thirst, fever or cardiovascular regulation. This review focuses on the possible physiological relevance of VP acting on sensory Circumventricular Organs in view of recent evidence obtained from biochemical and electrophysiological studies at the cellular level.
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AVP-fragment peptides induce Ca2+ transients in cells cultured from rat Circumventricular Organs.
Brain research, 1995Co-Authors: Mirek Jurzak, Andreas Müller, Rüdiger GerstbergerAbstract:To investigate receptors for the naturally occurring fragments of [Arg8]vasoperssin (AVP), Ca2+ measurements were performed in cells cultured from the subfornical organ (SFO) and the organum vasculosum of the lamina terminalis (OVLT). AVP(4–9) and AVP(4–8) applied in nanomolar concentrations triggered rises in the intracellular Ca2+ concentration in neurons and astrocytes cultured from both Circumventricular Organs (CVOs) which are located in the lamina terminalis of the rat brain. The determination of the investigated cell type was confirmed by immunocytochemistry with cell type-specific antibodies. The functional data from single cultured cells and receptor autoradiographic studies on tissue slices favour the existence of specific receptors for AVP fragments which are different from those for the paternal AVP.
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Primary culture of Circumventricular Organs from the rat brain lamina terminalis
Brain Research, 1994Co-Authors: Mirek Jurzak, Andreas Müller, Herbert A. Schmid, Rüdiger GerstbergerAbstract:A primary culture system of cells derived from two Circumventricular Organs (CVO) of the rat brain was established. The subfornical organ (SFO) and the organum vasculosum of the lamina terminalis (OVLT) were dissected from the rostral wall of the third ventricle and its cells taken into culture after mechanical dissociation. The cells were cultured in a modified microculture chamber system ensuring relatively high cell density despite their low absolute number. When animals were injected with Evans blue prior to cell preparation, the macroscopically visible penetration of the dye into the parenchyma of the CVOs could be used as guidance during tissue isolation and labelled cells could be identified in culture. Cultured CVO neurones and astrocytes were identified using antibodies against cell type specific marker proteins. The histochemical NADPH-diaphorase staining was used for the detection of nitric oxide synthase in tissue sections of both CVOs and in their cultured neurones. In addition, angiotensin II (ANG II)-evoked elevations of the intracellular Ca2+ concentration ([Ca2+]i) in single cultured OVLT neurones were measured. The described methods will be useful for further characterization of CVO neurones and astrocytes.