Transection of subfornical organ neural connections diminishes the pressor response to intravenously infused angiotensin II

Lind, R.W.; Ohman, Lynne E.; Lansing, Mary B.; Johnson, Alan Kim

doi:10.1016/0006-8993(83)90998-8

Cited by 60 publications

(24 citation statements)

References 16 publications

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“…Recent studies have suggested that the circumventricular structures of the brain, which lack the normal blood-brain barrier [3], provide specialized sites where peptides may gain direct ac cess to CNS tissue and through the efferent neural projec tions of these structures influence a wide variety of regu latory functions. In particular the subfornical organ (SFO) is now well established as the CNS structure at which syste mic angiotensin II (All) acts to cause drinking [21], vaso pressin release from the posterior pituitary [8,10], and inReceived: July 10, 1987 Accepted after revision: November 4, 1987 creases in arterial blood pressure [11,14]. The SFO has been shown to send dense efferent neural projections to a variety of hypothalamic neuroregulatory control centres including the supraoptic and paraventricular (PVN) nuclei [13,15].…”

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confidence: 99%

Systemic Angiotensin Acts at the Subfornical Organ to Control the Activity of Paraventricular Nucleus Neurons with Identified Projections to the Median Eminence

Ferguson

1988

Neuroendocrinology

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The present studies were carried out to investigate the mechanisms through which systemic angiotensin II (AII) acts within the central nervous system to influence the release of anterior pituitary hormones in the Sprague-Dawley rat. In particular, these studies have examined the role of the subfornical organ (SFO) as an essential structure mediating these responses. Extracellular single-unit recordings were obtained from 199 paraventricular nucleus (PVN) neurons anti-dromically identified as projecting to the median eminence. Different groups of these neurons were tested for the effects of either electrical stimulation in the SFO (n = 87) or systemic AII administration in intact (n = 49) and SFO-lesioned (n = 25) animals. Of cells tested with SFO stimulation 45% were excited, 16% inhibited, and the remainder unaffected. Neurons which were excited were primarily located just medial to the magnocellular neurons in the region where the majority of corticotropin-releasing hormone immunoreactive cells are found. In contrast, inhibitory responses were observed in cells located in the dorsal medial PVN, a region containing thyrotropin-releasing hormone, somatostatin, and dopamine PVN-median eminence neurons. Following systemic AII 42% of cells tested showed increased activity specific to the effects of this peptide, and 20% showed alterations in activity associated with the cardiovascular changes induced by AII. In contrast, following SFO lesion only 8% of neurons tested showed specific excitatory responses to AII. In order to test the hypothesis that systemic AII may activate this excitatory SFO to PVN pathway, a further group of 35 neurons were tested with both SFO stimulation and AII. Excitatory responses to AII were observed in 13 of these cells, each of which was also excited by SFO stimulation. These studies describe mechanisms through which the central nervous system may sense peripheral concentrations of peptide hormones and modulate the activity of neural pathways which in turn influence the activity of PVN neurons which control the secretion of anterior pituitary hormones.

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confidence: 99%

Systemic Angiotensin Acts at the Subfornical Organ to Control the Activity of Paraventricular Nucleus Neurons with Identified Projections to the Median Eminence

Ferguson

1988

Neuroendocrinology

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“…The current findings provide further evidence that the site of action of blood-borne ANG II is outside the anterior AV3V region. It could be argued that bolus l.v injections of ANG II are not a satisfactory way to evaluate the central action of the peptide, since Lind et al 24 observed that in rats with knife cuts of the ventral stalk of the SFO there was a statistically significant attenuation of the pressor response during infusion but not injection of ANG II intravenously. In their study, however, both the injection and the infusion techniques produced comparable downward shifts of dose-dependent responses.…”

Section: Discussionmentioning

confidence: 99%

“…In dogs it has been suggested that the OVLT mediates drinking in response to changes in plasma Na + and osmolality, while the subfornical organ (SFO) may be responsible for ANG II-induced drinking. 15 " On the other hand, Lind et al 24 have shown that transection of neural connections close to the main body of the SFO in rats attenuates the dipsogenic response to subcutaneous injection of ANG II and hypertonic NaCl. Given that Miselis 25 has shown efferent projections from the SFO to and through the dorsal and anterior NM, and Camacho and Phillips 26 have described similar projections from the OVLT through the ventral NM, a lesion of the aAV3V + NM may produce adipsia despite the presence of increased plasma Na + levels, osmolality, and irANG II levels.…”

Section: Discussionmentioning

confidence: 99%

The anteroventral third ventricle region. Participation in the regulation of blood pressure in conscious dogs.

Marson¹,

Chernicky²,

Barnes³

et al. 1985

Hypertension

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The anteroventral third ventricle (AV3V) region plays an important role in fluid and electrolyte balance and cardiovascular control in the rat; however, experiments in other species have raised questions about the universality of findings in the rat. The effects of discrete lesions placed within the AV3V area on hydromineral balance, the pressor response to angiotensin II given intravenously , and the initiation of a renin-dependent model of hypertension were examined in the dog. A transpharyngeal approach to the optic chiasm enabled us to destroy only the anterior aspects of the AV3V region (aAV3V group) or to include the entire nucleus medianus (NM) as well (aAV3V + NM group). Lesions of the aAVJV caused polydipsia and transient hvpernatremia and hyperosmolality. In contrast, adipsia and a sustained increase in plasma sodium levels and osmolality were observed in dogs with lesions of the aAV3V plus the entire NM. Neither lesion altered baseline arterial pressure, heart rate, plasma levels of catecholamines and vasopressin, or total plasma protein levels. Only in aAV3V + NM lesioned dogs was there a tendency for plasma angiotensin II immunoreactivity to be elevated above control values at 2 and 4 days after operation. Neither lesion attenuated the pressor response to intravenous angiotension II or the initiation of renal hypertension induced by aortic coarctation. As observed in other species, structures within the AV3V region participate in hydromin-eral balance in the dog; however, in the dog portions of the NM dorsal to the AV3V region are essential for the mediation of drinking behavior. Because initiation of a renin-dependent hypertension was not altered by either aAV3V or aAV3V + NM lesions, these structures, although involved in the regulation of fluid balance, do not appear to mediate the central pressor actions of blood-borne angiotensin II in the dog. (Hypertension 7 [Suppl I]: I-80-1-87, 1985) KEY WORDS • angiotensin II • fluid and electrolyte control • forebrain lesions • nucleus medianus * sodium chloride • renal hypertension * thirst * vasopressin T HE endocrine hypothalamus and its associated afferent and efferent pathways are increasingly recognized as being critically involved in integrating the hemodynamic, humoral, and hormonal events that accompany the production of high blood pressure The studies of Buggy et al. rat's third ventricle (AV3V) participate in the expression of drinking behavior and the production and reversal of various forms of hypertension. Other studies in rats have validated these original experiments and uncovered additional evidence about the mechanisms involved in these effects 1-6 Given the availability of detailed anatomical maps of the rat brain, and of strains with genetic disorders of neuroendocrine function , it is not surprising that much of the knowledge about the AV3V region has been obtained in this species It is not clear how much of the data obtained in rats is directly applicable to other species, including humans. Although studies in species other than the ...

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“…1966] and the presence of Gomori-positive material in the dendrites of the neurons [Diericks, 1962], It is known that the SFO par ticipates in the elevations of plasma vasopressin -due to its connections with the paraventricular nucleus -increases in arterial blood pressure observed 1 Supported by the 'Consejería de Educación del Gobierno de la Comunidad Autónoma de Canarias',Project No. 1/22.04.85. in response to angiotensin II [Lind et al. 1983] and drink ing behavior induced by angiotensin II Routtenberg, 1975: Mangiapane andSimpson.…”

Section: Introductionmentioning

confidence: 99%

Development of the Subfornical Organ and Area postrema of the Male Albino Mouse.Karyometric Effect of Neonatal and Prepuberal Castration

Castañeyra-Perdomo

Pérez-Delgado²,

González‐Hernández³

et al. 1988

Cells Tissues Organs

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We have studied the karyometric development of the nuclei of the ependymal cells and neurons of the subfornical organ and the area postrema in the male albino mouse from the 5th to the 190th postnatal day. We have found similar patterns of development in both although the area postrema showed more significant postnatal oscillations than those of the subfornical organ, suggesting a more intimate chronological relationship to gonadal development. We have furthermore analyzed the development in two experimental groups: in the one animals were castrated at birth, in the other, castration was made on the 20th postnatal day. We have found that neonatal castration produced a significant decrease of nuclear sizes; this was more evident in the subfornical organ than in the area postrema in earlier stages of development while the response was similar in both at peripuberal ages. The response to prepuberal castration was similar in both organs.

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Transection of subfornical organ neural connections diminishes the pressor response to intravenously infused angiotensin II

Cited by 60 publications

References 16 publications

Systemic Angiotensin Acts at the Subfornical Organ to Control the Activity of Paraventricular Nucleus Neurons with Identified Projections to the Median Eminence

Systemic Angiotensin Acts at the Subfornical Organ to Control the Activity of Paraventricular Nucleus Neurons with Identified Projections to the Median Eminence

The anteroventral third ventricle region. Participation in the regulation of blood pressure in conscious dogs.

Development of the Subfornical Organ and Area postrema of the Male Albino Mouse.Karyometric Effect of Neonatal and Prepuberal Castration

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