Immunocytochemical localization of angiotensinogen in the rat brain

Thomas, Walter G.; Sernia, Conrad

doi:10.1016/0306-4522(88)90029-2

Cited by 99 publications

(80 citation statements)

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“…The size and distribution of these angiotensinogen staining cells was not consistent with the size and distribution of glandular pituitary cells and hence their cell type is unknown. In addition, because these cells did not stain for AII, it is possible that they are secreting angiotensinogen for uptake by other pituitary cells in a manner similar to that proposed for astrocytes in the brain (33,41). Like Healy and Printz (30), we found angiotensinogen immunostaining in the posterior pituitary.…”

Section: Discussionmentioning

confidence: 99%

“…The production and characterization of these antibodies has been described previously (33). An antiserum against A11 (CD,) was kindly donated by Dr C. Deschepper.…”

Section: Anrirerumentioning

confidence: 99%

“…First, angiotensinogen and A11 were detected with the avidin-biotin-peroxidase staining system, using specific primary antibodies which have been previously described (26,33). Secondly, lightly staining areas were markedly intensified by the recently developed method of silver intensification (34).…”

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confidence: 99%

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Immunocytochemical Localization of Angiotensinogen and Angiotensin II in the Rat Pituitary

Thomas

Sernia

1990

J Neuroendocrinology

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The presence and distribution of angiotensinogen and angiotensin II (All) were demonstrated in rat pituitary by immunocytochemical staining with the avidin-biotin-peroxidase method, using primary polyclonal antibodies specific for angiotensinogen and All. Silver enhancement of the reaction product was used to intensify lightly stained areas. Attempts were made to identify immunopositive cells by colocalization studies with antisera against luteinizing hormone, prolactin and S-100, a glial cell protein. In the anterior pituitary, angiotensinogen-immunoreactivity was observed in cells lining follicle-like structures. These cells, which were irregularly shaped and had processes extending between the glandular cells, did not colocalize with any of the reference antisera and are therefore of unknown cell type. The follicular endothelium was also immunopositive for angiotensinogen. After silver intensification, dispersed immunoreactive glandular cells were consistently observed in the anterior lobe. A proportion of these costained for luteinizing hormone, but not prolactin or S-100, indicating their identity as gonadotrophs. In the posterior pituitary, angiotensinogen immunostaining was associated only with the vasculature, while groups of immunopositive cells were observed in the medial region of the intermediate lobe after silver enhancement. All-immunoreactivity was observed in large cells preferentially located a t the poles of the anterior pituitary which also costained for luteinizing hormone. No staining was observed in either the posterior or intermediate lobes. The presence of immunoreactive angiotensinogen in all three lobes of the pituitary suggests that there a r e sites, in addition to gonadotrophs, at which the intracellular production of All could occur.The octapeptide angiotensin IT (AII) regulates the release of several hormones from the anterior pituitary. In both in vivo and in vifro, A11 is a stimulus for the secretion of prolactin (PRL) (1-4), adrenocorticotrophin (ACTH) ( 5 , 6), luteinizing hormone (LH) (7) and P-endorphin (8). These effects may be mediated by specific A11 receptors located on pituitary cells (9-11) or A11 may function through intermediate releasing factors, such as corticotrophin-releasing factor, as is the case for AH-stimulated release of ACTH (1 2-1 5). Of interest is the possibility that the pituitary is synthesizing and secreting AII, as part of an endogenous reninangiotensin system (RAS), to directly alter pituitary function.Several observations support the idea of a functioning RAS in the pituitary: 1) the demonstration of renin (16-19) and converting enzyme in the pituitary (20-23); 2) the detection of renin mRNA in pituitary extracts (24); 3) the identification and HPLC characterization of A11 from the hypophysis (25, 26); 4) the colocalization, by immunocytochemistry, of both renin and A11 in the rat gonadotroph (19,27) or human lactotroph (28); and 5) the demonstration of specific A11 receptors in the pituitary (9-1 1). However, the existence of angiotensino...

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Section: Discussionmentioning

confidence: 99%

“…The production and characterization of these antibodies has been described previously (33). An antiserum against A11 (CD,) was kindly donated by Dr C. Deschepper.…”

Section: Anrirerumentioning

confidence: 99%

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Immunocytochemical Localization of Angiotensinogen and Angiotensin II in the Rat Pituitary

Thomas

Sernia

1990

J Neuroendocrinology

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“…In the brain, AGT expression is localized mainly in astrocytes (glia) (7,8). To determine whether locally synthesized AGT can be processed to Ang-II in the brain, we generated a transgenic mouse model expressing human AGT (hAGT) under the control of an astrocyte-specific (glial fibrillary acidic protein (GFAP)) promoter (GFAP-hAGT) (9).…”

Section: The Peptide Angiotensin II (Ang-ii)mentioning

confidence: 99%

“…Accordingly, we concluded that AGT synthesized in the brain can be converted to Ang-II if renin is present. In addition to glia, AGT is expressed in select populations of neurons in regions of the brain, such as the subfornical organ, that can influence cardiovascular function (7,11). To determine the relevance of neuronal AGT, we also developed a transgene overexpressing hAGT from a neuronal promoter, synapsin-I (SYN) (12).…”

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confidence: 99%

Glia- and Neuron-specific Expression of the Renin-Angiotensin System in Brain Alters Blood Pressure, Water Intake, and Salt Preference

Morimoto

Cassell

Sigmund

2002

Journal of Biological Chemistry

107

124

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The purpose of this study is to examine the regulation of blood pressure and fluid and electrolyte homeostasis in mice overexpressing angiotensin II (Ang-II) in the brain and to determine whether there are significant physiologic differences in Ang-II production in neurons or glia. Therefore, we generated and characterized transgenic mice overexpressing human renin (hREN) under the control of the glial fibrillary acidic protein (GFAP) promoter (GFAP-hREN) and synapsin-I promoter (SYN-hREN) and bred them with mice expressing human angiotensinogen (hAGT) under the control of the same promoters (GFAP-hAGT and SYN-hAGT). Both GFAP-hREN and SYN-hREN mice exhibited the highest hREN mRNA expression in the brain and had undetectable levels of hREN protein in the systemic circulation. In the brain of GFAP-hREN and SYN-hREN mice, hREN protein was observed almost exclusively in astrocytes and neurons, respectively. Transgenic mice overexpressing both hREN and hAGT transgenes in either glia or neurons were moderately hypertensive. In the gliatargeted mice, blood pressure could be corrected by intracerebroventricular injection of the Ang-II type 1 receptor antagonist losartan, and intravenous injection of a ganglion blocking agent, but not an arginine vasopressin V1 receptor antagonist, lowered blood pressure. These data suggest that stimulation of Ang-II type 1 receptors in the brain by Ang-II derived from local synthesis of renin and angiotensinogen can cause an elevation in blood pressure via a mechanism involving enhanced sympathetic outflow. Glia-and neuron-targeted mice also exhibited an increase in drinking volume and salt preference, suggesting that chronic overexpression of renin and angiotensinogen locally in the brain can result in hypertension and alterations in fluid homeostasis. The peptide angiotensin II (Ang-II)1 is the main circulating effector hormone of the renin-angiotensin system (RAS) and is able to act not only on peripheral vascular structures but also on the central nervous system (CNS) to increase blood pressure (BP) (1). Substantial evidence has accumulated that Ang-II has actions on the CNS including increasing sympathetic outflow, arginine vasopressin (AVP) release, water intake, and salt appetite (2). Existence of a local RAS in the CNS has been suggested, since all components of this system have been reported in the brain. In addition, several lines of evidence point to a contribution of an overactive brain RAS to the hypertensive state in spontaneously hypertensive rats, deoxycorticosterone acetate (DOCA) salt hypertensive rats, Dahl salt sensitive rats, and renal hypertensive rats (3-6).Despite numerous studies demonstrating the important cardiovascular effects of Ang-II or Ang-II receptor antagonists injected into the brain, it remains unclear whether RAS components synthesized in the brain, in particular renin and angiotensinogen (AGT), have an important role in the local synthesis of Ang-II. In the brain, AGT expression is localized mainly in astrocytes (glia) (7,8). To determine whether l...

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Interhemispheric connections between the infralimbic and entorhinal cortices: The endopiriform nucleus has limbic connections that parallel the sensory and motor connections of the claustrum

Watson

Smith

Alloway

2016

J of Comparative Neurology

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We have previously shown that the claustrum is part of an interhemispheric circuit that interconnects somesthetic-motor and visual-motor cortical regions. The role of the claustrum in processing limbic information, however, is poorly understood. Some evidence suggests that the dorsal endopiriform nucleus (DEn), which lies immediately ventral to the claustrum, has connections with limbic cortical areas and should be considered part of a claustrum-DEn complex. To determine whether DEn has similar patterns of cortical connections as the claustrum, we used anterograde and retrograde tracing techniques to elucidate the connectivity of DEn. Following injections of retrograde tracers into DEn, labeled neurons appeared bilaterally in the infralimbic (IL) cortex and ipsilaterally in the entorhinal and piriform cortices. Anterograde tracer injections in DEn revealed labeled terminals in the same cortical regions, but only in the ipsilateral hemisphere. These tracer injections also revealed extensive longitudinal projections throughout the rostrocaudal extent of the nucleus. Dual retrograde tracer injections into IL and lateral entorhinal cortex (LEnt) revealed intermingling of labeled neurons in ipsilateral DEn, including many double-labeled neurons. In other experiments, anterograde and retrograde tracers were separately injected into IL of each hemisphere of the same animal. This revealed an interhemispheric circuit in which IL projects bilaterally to DEn, with the densest terminal labeling appearing in the contralateral hemisphere around retrogradely-labeled neurons that project to IL in that hemisphere. By showing that DEn and claustrum have parallel sets of connections, these results suggest that DEn and claustrum perform similar functions in processing limbic and sensorimotor information, respectively.

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Immunocytochemical localization of angiotensinogen in the rat brain

Cited by 99 publications

References 49 publications

Immunocytochemical Localization of Angiotensinogen and Angiotensin II in the Rat Pituitary

Immunocytochemical Localization of Angiotensinogen and Angiotensin II in the Rat Pituitary

Glia- and Neuron-specific Expression of the Renin-Angiotensin System in Brain Alters Blood Pressure, Water Intake, and Salt Preference

Interhemispheric connections between the infralimbic and entorhinal cortices: The endopiriform nucleus has limbic connections that parallel the sensory and motor connections of the claustrum

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