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1.
Peptides ; 29(11): 2013-23, 2008 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-18692535

RESUMO

In recent years, evidence has accumulated that many endogenous peptides play an important regulatory role in angiogenesis by modulating endothelial cell behavior. Adrenomedullin (AM), one such factor, was previously shown to exert a clearcut proangiogenic effect in vitro when tested on specialized human endothelial cells, such as HUVECs and immortalized endothelial cell lines. In the present study we used normal adult vascular endothelial cells isolated from human saphenous vein to analyze in vitro the role of AM, related to both early (increased cell proliferation) and late (differentiation and self-organization into capillary-like structures) angiogenic events and their relationship with the vascular endothelial growth factor (VEGF) signaling cascade. The results indicated that also in this endothelial cell phenotype AM promoted cell proliferation and differentiation into cord-like structures. These actions resulted specific and were mediated by the binding of AM to its AM1 (CRLR/RAMP2) receptor. Neither the administration of a VEGF receptor 2 (VEGFR-2) antagonist nor the downregulation of VEGF production by gene silencing were able to suppress the proangiogenic effect of AM. However, when the experiments were performed in the presence of SU5416 (a selective inhibitor of the VEGFR-2 receptor at the level of the intra-cellular tyrosine kinase domain) the proangiogenic effect of AM was abolished. This result suggests that in vascular endothelial cells the binding of AM to its AM1 receptor could trigger a transactivation of the VEGFR-2 receptor, leading to a signaling cascade inducing proangiogenic events in the cells.


Assuntos
Adrenomedulina/farmacologia , Endotélio Vascular/efeitos dos fármacos , Neovascularização Fisiológica/efeitos dos fármacos , Receptor 2 de Fatores de Crescimento do Endotélio Vascular/fisiologia , Inibidores da Angiogênese/farmacologia , Diferenciação Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Células Endoteliais/efeitos dos fármacos , Células Endoteliais/fisiologia , Endotélio Vascular/fisiologia , Fator 2 de Crescimento de Fibroblastos/farmacologia , Inativação Gênica , Humanos , Fator A de Crescimento do Endotélio Vascular/genética , Fator A de Crescimento do Endotélio Vascular/metabolismo , Receptor 2 de Fatores de Crescimento do Endotélio Vascular/antagonistas & inibidores
2.
Int Rev Cytol ; 249: 1-51, 2006.
Artigo em Inglês | MEDLINE | ID: mdl-16697281

RESUMO

Vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase-activating polypeptide (PACAP) are the main endogenous ligands of a class of G protein-coupled receptors (Rs). Three subtypes of PACAP/VIP Rs have been identified and named PAC(1)-Rs, VPAC(1)-Rs, and VPAC(2)-Rs. The PAC(1)-R almost exclusively binds PACAP, while the other two subtypes bind with about equal efficiency VIP and PACAP. VIP, PACAP, and their receptors are widely distributed in the body tissues, including the adrenal gland. VIP and PACAP are synthesized in adrenomedullary chromaffin cells, and are released in the adrenal cortex and medulla by VIPergic and PACAPergic nerve fibers. PAC(1)-Rs are almost exclusively present in the adrenal medulla, while VPAC(1)-Rs and VPAC(2)-Rs are expressed in both the adrenal cortex and medulla. Evidence indicates that VIP and PACAP, acting via VPAC(1)-Rs and VPAC(2)-Rs coupled to adenylate cyclase (AC)- and phospholipase C (PLC)-dependent cascades, stimulate aldosterone secretion from zona glomerulosa (ZG) cells. There is also proof that they can also enhance aldosterone secretion indirectly, by eliciting the release from medullary chromaffin cells of catecholamines and adrenocorticotropic hormone (ACTH), which in turn may act on the cortical cells in a paracrine manner. The involvement of VIP and PACAP in the regulation of glucocorticoid secretion from inner adrenocortical cells is doubtful and surely of minor relevance. VIP and PACAP stimulate the synthesis and release of adrenomedullary catecholamines, and all three subtypes of PACAP/VIP Rs mediate this effect, PAC(1)-Rs being coupled to AC, VPAC(1)-Rs to both AC and PLC, and VPAC(2)-Rs only to PLC. A privotal role in the catecholamine secretagogue action of VIP and PACAP is played by Ca(2+). VIP and PACAP may also modulate the growth of the adrenal cortex and medulla. The concentrations attained by VIP and PACAP in the blood rule out the possibility that they act as true circulating hormones. Conversely, their adrenal content is consistent with a local autocrine-paracrine mechanism of action.


Assuntos
Glândulas Suprarrenais/fisiologia , Comunicação Autócrina , Comunicação Parácrina , Receptores de Polipeptídeo Hipofisário Ativador de Adenilato Ciclase/genética , Receptores de Peptídeo Intestinal Vasoativo/metabolismo , Glândulas Suprarrenais/metabolismo , Medula Suprarrenal/crescimento & desenvolvimento , Medula Suprarrenal/metabolismo , Sequência de Aminoácidos , Animais , Humanos , Ligantes , Dados de Sequência Molecular , Receptores de Polipeptídeo Hipofisário Ativador de Adenilato Ciclase/metabolismo , Receptores de Peptídeo Intestinal Vasoativo/genética
3.
Int J Mol Med ; 19(1): 149-55, 2007 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-17143559

RESUMO

Galanin is a regulatory peptide, which acts via three subtypes of receptors, named GAL-R1, GAL-R2 and GAL-R3. Reverse transcription-polymerase chain reaction demonstrated the expression of GAL-R1 and GAL-R2, but not GAL-R3 mRNAs in dispersed rat adrenal zona fasciculata-reticularis (inner) cells. The immuno-blockade of GAL-R1 and GAL-R2, but not GAL-R3, decreased the binding of [3H]galanin to dispersed cells, a complete inhibition being obtained only by the simultaneous blockade of both receptor subtypes. Galanin stimulated corticosterone and cyclic-AMP release from dispersed inner rat adrenocortical cells, while inositol triphosphate production was not affected. Again these responses to galanin were reversed by both the GAL-R1 and GAL-R2, but not the GAL-R3 immuno-blockade. The adenylate cyclase inhibitor SQ-22536 and the protein kinase (PK) A inhibitor H-89 abolished the corticosterone response of dispersed cells to galanin, while the phospholipase C inhibitor U-73122 and the PKC inhibitor calphostin-C were ineffective. We conclude that rat inner adrenocortical cells express GAL-R1 and GAL-R2 as mRNA and protein, and galanin stimulates corticosterone secretion acting via these receptor subtypes which are both coupled to the adenylate cyclase/PKA-dependent signaling pathway.


Assuntos
Adenilil Ciclases/metabolismo , Córtex Suprarrenal/metabolismo , Corticosterona/metabolismo , Galanina/farmacologia , Receptor Tipo 1 de Galanina/metabolismo , Receptor Tipo 2 de Galanina/metabolismo , Córtex Suprarrenal/citologia , Córtex Suprarrenal/enzimologia , Animais , Masculino , Reação em Cadeia da Polimerase/métodos , Ratos , Ratos Sprague-Dawley , Transdução de Sinais
4.
Int J Mol Med ; 19(3): 511-5, 2007 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-17273801

RESUMO

Previous investigations have shown that rat adrenocortical cells are provided with galanin receptors, and galanin stimulates glucocorticoid secretion from dispersed cells. The present study aimed to clarify the possible role of galanin in the physiological regulation of rat adrenal secretory activity. Reverse transcription-polymerase chain reaction detected galanin mRNA expression in the adrenal medulla, but not in the cortex. Sizeable concentrations of galanin-immunoreactivity were measured by radioimmune assay only in the adrenomedullary tissue. Galanin raised norepinephrine, but not epinephrine, release from adrenomedullary tissue. Galanin immunoneutralization (obtained with concentrations of anti-galanin antibody able to block the galanin glucocorticoid secretagogue effect on dispersed adrenocortical cells) decreased basal corticosterone production from adrenal slices containing adrenomedullary tissue, without affecting that from dispersed adrenocortical cells. The beta-adrenoceptor antagonist l-alprenolol partially prevented galanin-stimulated corticosterone secretion from adrenal slices, without per se altering basal secretion. Taken together, our findings allow us to conclude that endogenous galanin, produced in adrenal medulla, is involved in the regulation of adrenocortical glucocorticoid secretion acting via a two-fold paracrine mechanism: i) direct activation of adrenocortical galanin receptors; and ii) stimulation of adrenomedullary release of catecholamines, which in turn activate beta-adrenoceptors located on adrenocortical cells.


Assuntos
Medula Suprarrenal/metabolismo , Corticosterona/metabolismo , Galanina/metabolismo , Comunicação Parácrina , Medula Suprarrenal/efeitos dos fármacos , Alprenolol/farmacologia , Animais , Catecolaminas/metabolismo , Galanina/genética , Galanina/farmacologia , Regulação da Expressão Gênica/efeitos dos fármacos , Masculino , Testes de Neutralização , Comunicação Parácrina/efeitos dos fármacos , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Ratos , Ratos Sprague-Dawley
5.
Int J Mol Med ; 17(2): 319-21, 2006 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-16391832

RESUMO

Numerous lines of evidence indicate that ghrelin, an endogenous ligand of the growth hormone-secretagogue receptor, is expressed in the human and rat adrenal cortex. In this study, we examined whether ghrelin gene expression undergoes changes in the human adrenal cortex during aging. Semi-quantitative real-time reverse transcription-polymerase chain reaction demonstrated a highly significant negative correlation between ghrelin mRNA and age in adrenal cortex of 27 patients (aged from 33 to 82 years), who underwent unilateral adrenalectomy/nephrectomy for kidney cancer. No significant differences in the level of adrenal ghrelin expression were observed between males and females. Since it has been previously shown that ghrelin exerts a marked growth-stimulating action on cultured adrenocortical cells, we hypothesize that the down-regulation of ghrelin gene transcription in adrenals could be associated with the reported decrease in adrenal DNA synthesis and mitogenic activity during aging.


Assuntos
Córtex Suprarrenal/metabolismo , Envelhecimento/genética , Regulação para Baixo/genética , Hormônios Peptídicos/genética , Adulto , Distribuição por Idade , Idoso , Idoso de 80 Anos ou mais , Feminino , Grelina , Humanos , Masculino , Pessoa de Meia-Idade , RNA Mensageiro/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Caracteres Sexuais
6.
Int J Mol Med ; 18(4): 615-8, 2006 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-16964413

RESUMO

Leptin is an adipose tissue-secreted hormone that acts via specific receptors (Ob-R), of which six isoforms are at present recognized (from Ob-Ra to Ob-Rf). Ob-Rb is the only isoform able to activate JAK-STAT and MAPK signaling cascades. A large body of evidence suggests that leptin and its receptors are involved in prostate physiology and pathophysiology in humans, but studies on the leptin system in the rat prostate are lacking. Reverse transcription-polymerase chain reaction showed the expression of mRNAs of leptin, Ob-Ra, Ob-Rb, Ob-Rc, Ob-Re and Ob-Rf in adult rat seminal vesicles and prostate (coagulating, dorsal, ventral and lateral lobes). Western blotting demonstrated the presence in these specimens of the Ob-Rb protein, and immunocytochemistry revealed that Ob-Rb was mainly located in their epithelial-cell component. Collectively, these findings strongly suggest that leptin and Ob-R may be involved in the autocrine-paracrine functional regulation of the epithelial cells of adult rat seminal vesicles and prostate.


Assuntos
Leptina/genética , Próstata/metabolismo , Receptores de Superfície Celular/genética , Glândulas Seminais/metabolismo , Animais , Western Blotting , Imuno-Histoquímica , Masculino , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Ratos , Ratos Wistar , Receptores de Superfície Celular/metabolismo , Receptores para Leptina , Reação em Cadeia da Polimerase Via Transcriptase Reversa
7.
Int J Mol Med ; 17(6): 1111-5, 2006 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-16685423

RESUMO

Urotensin-II (UII) is a potent hypertensive peptide, which has been recognized as an endogenous ligand of the G protein-coupled receptor (GPR)-14, now named UT-R. Real-time PCR demonstrated the expression of UII and UT-R mRNAs in both dispersed and in vitro cultured rat adrenocortical cells. UII concentration-dependently decreased basal, but not ACTH-stimulated, corticosterone secretion from cultured adrenocortical cells, and the effect was abolished by the UT-R antagonist Palosuran. UII did not affect the proliferation rate of cultured cells. Taken together, these findings suggest that UII may be included in the group of peptides (adrenomedullin, atrial natriuretic peptide, neurotensin and beacon), that, acting in an autocrine-paracrine manner, are involved in the inhibitory tuning of adrenocortical secretion.


Assuntos
Córtex Suprarrenal/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Urotensinas/metabolismo , Córtex Suprarrenal/efeitos dos fármacos , Hormônio Adrenocorticotrópico/farmacologia , Animais , Células Cultivadas , Masculino , Quinolinas/farmacologia , RNA Mensageiro/análise , RNA Mensageiro/metabolismo , Ratos , Ratos Sprague-Dawley , Receptores Acoplados a Proteínas G/antagonistas & inibidores , Receptores Acoplados a Proteínas G/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Ureia/análogos & derivados , Ureia/farmacologia , Urotensinas/genética
8.
Int J Mol Med ; 18(6): 1107-12, 2006 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-17089015

RESUMO

Urotensin-II (UII), along its receptor UT-R, is widely expressed in the cardiovascular system, where it exerts regulatory actions under both physiological and pathological conditions. Real-time PCR and immunocytochemistry demonstrated the expression of UII and UT-R as mRNA and protein in rat neuromicrovascular endothelial cells (NECs). UII did not affect the proliferation rate of cultured NECs, but exerted a strong angiogenic action in both an in vitro assay on Matrigel and an in vivo assay on chorioallantoic membrane. The angiogenic effect of UII was similar to that of FGF-2, and was abolished by the UT-R antagonist Palosuran. Collectively, our findings allow us to include UII in the group of cytokines (e.g. endothelin-1 and adrenomedullin), which are expressed in endothelial cells and exert a pro-angiogenic effect acting in an autocrine-paracrine manner.


Assuntos
Encéfalo/citologia , Membrana Corioalantoide/irrigação sanguínea , Células Endoteliais/metabolismo , Neovascularização Fisiológica/efeitos dos fármacos , Receptores Acoplados a Proteínas G/metabolismo , Urotensinas/metabolismo , Urotensinas/farmacologia , Animais , Divisão Celular , Células Cultivadas , Embrião de Galinha , Membrana Corioalantoide/efeitos dos fármacos , Células Endoteliais/citologia , Células Endoteliais/fisiologia , Endotélio Vascular/citologia , Imuno-Histoquímica , Separação Imunomagnética , Técnicas In Vitro , Masculino , Ratos , Ratos Sprague-Dawley , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Fatores de Tempo
9.
Int J Mol Med ; 17(5): 709-13, 2006 May.
Artigo em Inglês | MEDLINE | ID: mdl-16596251

RESUMO

Adrenomedullin (AM), a potent vasodilatory hypotensive peptide, is expressed in the heart, where it is known to play a protective action. Light-microscopy immunocytochemistry (ICC) demonstrated the presence of AM immunoreactivity not only in the coronary-vessel wall and ventricular myocytes of the human and rat heart, but also in sparse voluminous cells located in the perivascular space. These cells displayed the same location of toluidine blue-positive mast cells, and electron microscopy ICC showed AM-immunogold staining over the granules of rat cardiac mast cells. The incubation of rat left ventricle fragments with the mast-cell histamine releaser compound 48/80 evidenced groups of AM-positive cells undergoing degranulation and caused an increase of approximately 50% in the AM concentration in the incubation medium. Collectively, our findings provide evidence that at least a subset of cardiac mast cells are able to synthesize and store AM, and upon stimulation to release it near coronary arterioles and venules.


Assuntos
Mastócitos/química , Miocárdio/química , Peptídeos/análise , Adrenomedulina , Animais , Humanos , Imuno-Histoquímica , Masculino , Mastócitos/efeitos dos fármacos , Mastócitos/ultraestrutura , Microscopia Eletrônica , Miocárdio/citologia , Ratos , Ratos Sprague-Dawley , p-Metoxi-N-metilfenetilamina/farmacologia
10.
Int J Mol Med ; 17(6): 1101-10, 2006 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-16685422

RESUMO

Zona glomerulosa (ZG) cells cultured on plastic within few days dedifferentiate losing their capacity to secrete aldosterone (ALDO) in appreciable amounts. Evidence indicates that extracellular matrix modulates the secretory behavior of adrenocortical cells cultured in vitro. Hence, we compared the morphology and function of rat ZG cells grown on plastic and Matrigel basement membrane matrix (hereinafter Matrigel) for up to 12 days. At day 3, no significant differences were observed between cells cultured on plastic and Matrigel. Starting from day 6, ZG cells cultured on plastic lost their ultrastructural differentiated features (mitochondria with tubular cristae, smooth endoplasmic reticulum cisternae and lipid droplets), exhibiting a fibroblast-like appearance. The mRNA expression of the main steroidogenic enzymes, as evaluated by real-time polymerase chain reaction, the baseline secretion of ALDO and other post-pregnenolone hormones, as evaluated by high pressure liquid chromatography, and the secretory response to ACTH, angiotensin-II and K(+), as evaluated by radioimmunoassay, displayed a time-dependent decrease. Matrigel was found to maintain unchanged both the ultrastructure and the expresion of steroidogenic enzymes of ZG cells until day 12 of culture. Baseline and agonist-stimulated steroid-hormone secretion decreased with the duration of culture on Matrigel, but was always higher than that of ZG cells grown on plastic. Hence, our study clearly indicates that the culture on Matrigel favors the maintenance of rat ZG-cell differentiated phenotype, allowing the conclusion that this technique is suitable for long-term in vitro investigations.


Assuntos
Técnicas de Cultura de Células , Diferenciação Celular , Colágeno/farmacologia , Laminina/farmacologia , Proteoglicanas/farmacologia , Zona Glomerulosa/efeitos dos fármacos , Zona Glomerulosa/ultraestrutura , Hormônio Adrenocorticotrópico/farmacologia , Aldosterona/biossíntese , Aldosterona/metabolismo , Angiotensina II/farmacologia , Animais , Combinação de Medicamentos , Enzimas/genética , Enzimas/metabolismo , Masculino , Fenótipo , Plásticos/farmacologia , Potássio/farmacologia , RNA Mensageiro/análise , RNA Mensageiro/metabolismo , Ratos , Ratos Sprague-Dawley , Esteroides/biossíntese , Zona Glomerulosa/metabolismo
11.
Int J Mol Med ; 18(2): 315-9, 2006 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-16820940

RESUMO

Ouabain, an inhibitor of the Na+/K+-ATPase, has been reported to affect the secretory activity of the adrenal cortex, and especially of zona glomerulosa (ZG). However, conflicting results were obtained, depending on the experimental condition used since ouabain appears to interact with angiotensin-II (Ang-II) and its action to be influenced by the electrolyte balance. Hence, we investigated the effects of prolonged (4-month) infusion with ouabain on the rat adrenal cortex. Ouabain raised the plasma concentrations of aldosterone, corticosterone and endothelin-1 (ET-1), without affecting either systolic blood pressure (SBP) or plasma renin activity (PRA). The treatment caused a marked hypertrophy of ZG and ZG cells, which mainly ensued from increases in the volume of the mitochondrial and smooth-endoplasmic-reticulum compartments, where the enzymes of steroid synthesis are located. Conversely, the volume of the lipid-droplet compartment, which stores cholesterol utilized in steroid-hormone production, underwent a striking decrease. Zona fasciculata and its parenchymal cells were not affected. Basal and maximally agonist (ACTH, Ang-II and ET-1)-stimulated in vitro mineralocorticoid secretion from adrenal slices was also notably enhanced by ouabain administration. Collectively, these findings indicate that prolonged treatment with ouabain selectively stimulates the growth and steroidogenic capacity of the rat adrenal ZG. The possibility that the activation of the renin-angiotensin system may be involved in this effect of ouabain is ruled out by the lack of significant changes in SBP and PRA. Instead, our results suggest the possible involvement of ET-1, the plasma level of which is elevated in ouabain-infused rats.


Assuntos
Endotelina-1/sangue , Inibidores Enzimáticos/farmacologia , Ouabaína/farmacologia , Zona Glomerulosa/efeitos dos fármacos , Zona Glomerulosa/fisiologia , Aldosterona/sangue , Animais , Pressão Sanguínea , Corticosterona/sangue , Inibidores Enzimáticos/administração & dosagem , Humanos , Masculino , Ouabaína/administração & dosagem , Distribuição Aleatória , Ratos , Ratos Endogâmicos WKY , Renina/metabolismo , Zona Glomerulosa/anatomia & histologia
12.
J Steroid Biochem Mol Biol ; 96(5): 423-9, 2005 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-16157481

RESUMO

Orexins A and B are hypothalamic peptides, that act via two subtypes of receptors, named OX1-R and OX2-R. Rat and human adrenal cortexes are provided with both OX1-R and OX2-R, and we have previously shown that orexin-A, but not orexin-B, enhances glucocorticoid secretion from dispersed adrenocortical cells. Since OX1-Rs preferentially bind orexin-A and OX2-Rs are non-selective for both orexins, the hypothesis has been advanced that the secretagogue effect of orexin-A is exclusively mediated by the OX1-R. Here, we aimed to verify this contention and to gain insight into the signaling mechanism(s) underlying the secretagogue effect of orexins using primary cultures of rat and human adrenocortical cells. Reverse transcription-polymerase chain reaction showed that cultured cells, as freshly dispersed cells, expressed both OX1-R and OX2-R mRNAs. Orexin-A, but not orexin-B, concentration-dependently increased corticosterone and cortisol secretion from cultured rat and human adrenocortical cells, respectively. The blockade of OX1-Rs by selective antibodies abrogated the secretagogue effect of orexin-A, while the immuno-blockade of OX2-Rs was ineffective. The glucocorticoid response of cultured cells to orexin-A was annulled by the adenylate cyclase and protein kinase (PK) A inhibitors SQ-22536 and H-89, and unaffected by the phospholipase C and PKC inhibitors U-73122 and calphostin-C. Orexin-A, but not orexin-B, enhanced cyclic-AMP production from cultured cells, and did not alter inositol-3-phosphate release. Collectively, our present results allow us to conclude that orexins stimulate glucocorticoid secretion from rat and human adrenocortical cells, exclusively acting through OX1-Rs coupled to the adenylate cyclase/PKA-dependent signaling cascade.


Assuntos
Córtex Suprarrenal/fisiologia , Peptídeos e Proteínas de Sinalização Intracelular/fisiologia , Neuropeptídeos/fisiologia , Receptores de Neuropeptídeos/fisiologia , Córtex Suprarrenal/metabolismo , Animais , Células Cultivadas , Feminino , Glucocorticoides/metabolismo , Humanos , Masculino , Pessoa de Meia-Idade , Receptores de Orexina , Orexinas , RNA Mensageiro/metabolismo , Ratos , Receptores Acoplados a Proteínas G , Receptores de Neuropeptídeos/biossíntese , Receptores de Neuropeptídeos/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transdução de Sinais/fisiologia
13.
Peptides ; 26(9): 1670-5, 2005 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-16112409

RESUMO

Adrenomedullin (AM) is a 52 amino acid peptide originally isolated from human pheochromocytoma. It was initially demonstrated to have profound effects in vascular cell biology, since AM protects endothelial cells from apoptosis, promotes angiogenesis and affects vascular tone and permeability. This review article summarizes the literature data concerning the relationship between AM and angiogenesis and describes the relationship between vascular endothelial growth factor, hypoxia and AM and tumor angiogenesis. Finally, the role of AM as a potential target of antiangiogenic therapy is discussed.


Assuntos
Neovascularização Patológica/fisiopatologia , Neovascularização Fisiológica/fisiologia , Peptídeos/fisiologia , Adrenomedulina , Inibidores da Angiogênese/uso terapêutico , Animais , Expressão Gênica , Humanos , Hipóxia/metabolismo , Hipóxia/fisiopatologia , Neoplasias/irrigação sanguínea , Neoplasias/tratamento farmacológico , Neovascularização Patológica/metabolismo , Peptídeos/genética , Peptídeos/metabolismo , Fator A de Crescimento do Endotélio Vascular/genética , Fator A de Crescimento do Endotélio Vascular/metabolismo
14.
Int J Mol Med ; 15(1): 3-13, 2005 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-15583821

RESUMO

Neuropeptide-Y (NPY) is a 36-amino acid peptide, which belongs, along with peptide YY (PYY), to the pancreatic polypeptide (PP) family. The members of this family of peptides act via G protein-coupled receptors (Rs), six subtypes of which (from Y1- to Y6-R) have been identified. NPY and PYY preferentially bind the Y1-R, Y2-R and Y5-R, while PP mainly acts via the Y4-R. Evidence has been provided that the Y3-R is selective for NPY. NPY and Y-Rs are expressed in the adrenal gland (preferentially adrenal medulla) and pheochromocytomas, where they exert various autocrine-paracrine regulatory functions. Findings indicate that NPY is co-released with catecholamines under a variety of stimuli, including splanchnic nerve and cholinergic- and nicotinic-receptor activation. NPY, mainly acting via the Y1-R, Y2-R and Y3-R, either inhibits catecholamine secretion from bovine adrenal chromaffin cells or stimulates catecholamine secretion from adrenomedullary cells of humans and rats. NPY inhibits aldosterone secretion from dispersed zona glomerulosa (ZG) cells, but this effect has probably to be considered non-specific and toxic in nature, since it is obtained only using micromolar concentrations of the peptide. In contrast, NPY appears to modulate the secretory response of dispersed rat ZG cells to their main agonists (ACTH, angiotensin-II and potassium). However, there is indication that the main effect of NPY on the ZG in rats is indirect and involves the local release of catecholamines, which in turn, acting via beta-adrenoceptors, enhance the secretion of aldosterone. The prolonged treatment with NPY is also able to enhance the growth of the rat ZG. In contrast, the effects of NPY on glucocorticoid secretion from zona fasciculata-reticularis cells are negligible and doutbful. The physiological relevance of the effects of NPY on adrenal medulla and ZG remains to be addressed by future experimental studies employing more selective and potent Y-R antagonists. In contrast, indirect evidence is available that endogenous NPY system may play an important role in the modulation of adrenal functions under paraphysiological conditions (e.g. it seems to dampen exceedingly high responses to stresses). Moreover, it has been also suggested that endogenous NPY may be involved in the regulation of blood pressure and in the pathophysiology of pheochromocytomas.


Assuntos
Glândulas Suprarrenais/fisiologia , Glândulas Suprarrenais/fisiopatologia , Comunicação Autócrina , Neuropeptídeo Y/metabolismo , Comunicação Parácrina , Feocromocitoma/metabolismo , Receptores de Neuropeptídeo Y/metabolismo , Glândulas Suprarrenais/metabolismo , Glândulas Suprarrenais/patologia , Animais , Humanos , Neuropeptídeo Y/química , Feocromocitoma/patologia
15.
Int J Mol Med ; 15(3): 411-5, 2005 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-15702230

RESUMO

Cerebellin (CER) is a regulatory peptide, originally isolated from rat cerebellum, which derives from the cleavage of precerebellin (Cbln), three types of which (Cbln1-3) have been identified in humans and rats. CER is also expressed in several extra-cerebellar tissues, including adrenal gland, and evidence has been provided that CER exerts a modulatory action on human and rat adrenal gland. Hence, we have investigated the expression of Cbln1-3 mRNAs and CER protein-immunoreactivity (IR) in the various zones of rat adrenal glands, and the effects of CER and its metabolite [des-Ser(1)]CER (des-CER) on the secretion and growth of cultured rat adrenocortical cells. Reverse transcription-polymerase chain reaction showed high and low expression of Cbln2 mRNA in zona glomerulosa (ZG) and zona fasciculata-reticularis, respectively. Cbln1 was not expressed, and Cbln3 mRNA was detected only in ZG. No Cbln expression was found in adrenal medulla. Immunocytochemistry demonstrated the presence of CER-IR exclusively in the adrenal cortex, the reaction being more intense in ZG. As expected, ACTH (10(-8) M) markedly enhanced corticosterone secretion and lowered proliferation rate of cultured adrenocortical cells. CER was ineffective, while des-CER exerted an ACTH-like effect, but only at the lowest concentration (10(-10) M). Taken together, these findings allow us to conclude that CER is expressed in rat adrenal cortex, and to suggest that CER conversion to des-CER by endopeptidases is needed for CER to exert its autocrine-paracrine regulatory functions.


Assuntos
Glândulas Suprarrenais/efeitos dos fármacos , Glândulas Suprarrenais/metabolismo , Regulação da Expressão Gênica , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/farmacologia , Glândulas Suprarrenais/citologia , Animais , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Feminino , Masculino , Ratos , Ratos Wistar
16.
Int J Mol Med ; 16(2): 297-9, 2005 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-16012765

RESUMO

Beacon is a peptide expressed in the rat hypothalamus and adrenal cortex, which is involved in the central regulation of feeding and inhibits basal and agonist-stimulated glucocorticoid secretion from adrenocortical cells. In vivo studies on beacon have not yet been carried out, and therefore we investigated the effects of a subcutaneous (sc) injection of beacon on the response of rat hypothalamo-pituitary-adrenal axis to stress. Handling and sc injection per se elicited a moderate increase in the plasma concentrations of ACTH and corticosterone, which was counteracted by beacon. Similarly, beacon dampened ACTH and corticosterone responses to ether stress. In contrast, beacon did not affect ACTH response to cold stress, although it was able to induce a moderate lowering in the corticosterone response. Taken together, these findings allow us to draw the following conclusions: i) beacon inhibits handling/injection- and ether stress-activated, but not cold stress-activated, neural mechanism(s) responsible for stimulation of ACTH secretion and the ensuing increase in corticosterone production; and ii) the beacon-induced dampening in corticosterone response to stress also involves a direct inhibitory effect on the adrenal-cortex secretory activity. The physiological relevance of beacon as endogenous anti-stress agent remains to be evaluated.


Assuntos
Temperatura Baixa , Éter/toxicidade , Proteínas do Tecido Nervoso/farmacologia , Sistema Hipófise-Suprarrenal/efeitos dos fármacos , Hormônio Adrenocorticotrópico/sangue , Animais , Corticosterona/sangue , Feminino , Injeções Subcutâneas , Proteínas do Tecido Nervoso/administração & dosagem , Sistema Hipófise-Suprarrenal/fisiologia , Ratos , Ratos Wistar , Fatores de Tempo , Ubiquitinas
17.
Int J Mol Med ; 15(5): 847-52, 2005 May.
Artigo em Inglês | MEDLINE | ID: mdl-15806308

RESUMO

Orexin A and B are hypothalamic peptides that act through two subtypes of receptors named OX1-R and OX2-R. The OX1-R almost exclusively binds orexin-A, whereas OX2-R is non-selective for both orexins. We previously found that rat adrenocortical cells express both orexin-receptor subtypes, and orexin-A stimulates corticosterone secretion from dispersed adrenocortical cells acting via the OX1-R. Here, we examined the possibility that orexins, acting through both their receptor subtypes, modulate the growth of adrenocortical cells. Reverse transcription-polymerase chain reaction showed that rat adrenocortical cells cultured in vitro for four days expressed OX1-R and OX2-R mRNAs. Orexin-A increased the proliferation rate (PR) of cultured cells, while orexin-B lowered it. Using selective antibodies, we demonstrated that OX1-R immuno-blockade reversed the proliferogenic action of orexin-A, causing a sizeable decrease in PR. In contrast, OX2-R immuno-blockade magnified the proliferogenic effect of orexin-A and annulled the antiproliferogenic action of orexin-B. The proliferogenic effect of orexin-A in the presence of OX2-R immuno-blockade was abrogated by the MAPK p42/p44 inhibitor PD-98059, while the antiproliferogenic effect of orexin-A in the presence of OX1-R immuno-blockade was annulled by the MAPK p38 inhibitor SB-203580. Neither inhibitor altered per se the basal PR of cultured cells. Taken together, our present findings allow us to conclude that i) orexins modulate the growth of rat adrenocortical cells cultured in vitro, by exerting both proliferogenic and antiproliferogenic effects, which are mediated by OX1-Rs and OX2-Rs, respectively; and ii) OX1-R and OX2-R growth effects involve the activation of the MAPK p42/p44 and p38 signaling cascades, respectively.


Assuntos
Córtex Suprarrenal/citologia , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Proteína Quinase 3 Ativada por Mitógeno/metabolismo , Neuropeptídeos/metabolismo , Receptores de Neuropeptídeos/metabolismo , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismo , Animais , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Feminino , Imidazóis/farmacologia , Masculino , Proteína Quinase 1 Ativada por Mitógeno/antagonistas & inibidores , Proteína Quinase 3 Ativada por Mitógeno/antagonistas & inibidores , Receptores de Orexina , Orexinas , Compostos Orgânicos/farmacologia , Inibidores de Proteínas Quinases/farmacologia , Piridinas/farmacologia , Ratos , Ratos Wistar , Receptores Acoplados a Proteínas G , Receptores de Neuropeptídeos/biossíntese , Proteínas Quinases p38 Ativadas por Mitógeno/antagonistas & inibidores
18.
FEBS Lett ; 536(1-3): 173-9, 2003 Feb 11.
Artigo em Inglês | MEDLINE | ID: mdl-12586359

RESUMO

Ghrelin is an endogenous ligand of the growth hormone secretagogue receptor (GHS-R), which has been originally isolated from rat stomach. Evidence has been previously provided that adrenal gland possesses abundant ghrelin-displaceable GHS-Rs, but nothing is known about the possible role of ghrelin in the regulation of adrenocortical function. Reverse transcription-polymerase chain reaction demonstrated the expression of ghrelin and GHS-R in the rat adrenal cortex, and high adrenal concentrations of immunoreactive ghrelin were detected by radioimmune assay (RIA). Autoradiography localized abundant [(125)I]ghrelin binding sites in the adrenal zona glomerulosa (ZG) and outer zona fasciculata (ZF). Ghrelin (from 10(-10) to 10(-8) M) did not affect either basal steroid hormone (pregnenolone, progesterone, 11-deoxycorticosterone, corticosterone, 18-hydroxycorticosterone and aldosterone) secretion from dispersed ZG and zona fasciculata/reticularis (ZF/R) cells (as evaluated by quantitative high pressure liquid chromatography), or basal and agonist-stimulated aldosterone and corticosterone production from cultured ZG and ZF/R cells, respectively (as measured by RIA). Ghrelin (10(-8) and 10(-6) M) raised basal, but not agonist-stimulated, proliferation rate of cultured ZG cells (percent of cells able to incorporate 5-bromo-2'-deoxyuridine), without affecting apoptotic deletion rate (percent of cells able to incorporate biotinylated nucleosides into apoptotic DNA fragments). The tyrosine kinase (TK) inhibitor tyrphostin-23 and the p42/p44 mitogen-activated protein kinase (MAPK) inhibitor PD-98059 abolished the proliferogenic effect of 10(-8) M ghrelin, while the protein kinase A and C inhibitors H-89 and calphostin-C were ineffective. Ghrelin (10(-8) M) stimulated TK and MAPK activity of dispersed ZG cells, and the effect was abolished by preincubation with tyrphostin-23 and PD-98059, respectively. Tyrphostin-23 annulled ghrelin-induced activation of MAPK activity. Taken together, the present findings indicate that (i) ghrelin and GHS-R are both expressed in the rat adrenal cortex, ghrelin binding sites being very abundant in the ZG; (ii) ghrelin does not affect the secretory activity of rat adrenocortical cells, but significantly enhances the proliferation rate of cultured ZG cells, without affecting apoptotic deletion rate; and (iii) the ZG proliferogenic action of ghrelin involves the TK-dependent activation of the p42/p44 MAPK cascade.


Assuntos
Corticosteroides/metabolismo , Córtex Suprarrenal/metabolismo , Hormônios Peptídicos/metabolismo , Hormônios Peptídicos/farmacologia , Receptores de Superfície Celular/metabolismo , Receptores Acoplados a Proteínas G , Córtex Suprarrenal/efeitos dos fármacos , Glândulas Suprarrenais/química , Animais , Apoptose , Sítios de Ligação , Divisão Celular , Células Cultivadas , Grelina , Masculino , Modelos Biológicos , Hormônios Peptídicos/análise , Ratos , Ratos Sprague-Dawley , Receptores de Superfície Celular/genética , Receptores de Grelina , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transdução de Sinais , Transcrição Gênica , Zona Glomerulosa/citologia , Zona Glomerulosa/efeitos dos fármacos , Zona Glomerulosa/metabolismo
19.
Int J Oncol ; 25(6): 1781-7, 2004 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-15547717

RESUMO

Adrenomedullin (AM) is a hypotensive peptide, that acts via the calcitonin receptor-like receptor (CRLR), whose interaction with the subtypes 2 and 3 of a family of receptor activity-modifying proteins (RAMP) gives rise to two distinct AM receptors, named AM1 and AM2 receptors. AM derives from the post-translational proteolytic cleavage of pro(p)AM, the last step of which involves the conversion of the inactive AM to active AM by the peptidyl-glycine alpha-amidating monooxigenase (PAM). Compelling evidence suggests that AM, in addition to exerting its well-known regulatory action on blood pressure and water and electrolyte balance, also possesses a growth promoting effect in several normal and neoplastic tissues, including human prostate. Conventional reverse transcription (RT)-polymerase chain reaction (PCR) demonstrated the expression of pAM, PAM, CRLR and RAMP(1-3) mRNAs in both prostate hyperplasias (PH) and carcinomas (PC), and semiquantitative PCR showed that pAM, PAM and RAMP3 mRNA expression was higher in PCs than PHs. Radioimmunoassay measured higher concentrations of immunoreactive AM in PCs than PHs. The expression of pAM, CRLR and RAMP1,2 mRNAs was also detected in the PC-derived cell lines PC-3 and DU-145, RAMP3 expression being restricted to the latter line. AM did not affect the growth rate (duplication time) of PC-3 cells, but it did significantly increase that of DU-145 cells. The growth promoting effect of AM was found to ensue from both the rise in the proliferation rate and the lowering in the apoptosis rate of DU-145 cells. These effects of AM were counteracted by the AM receptor antagonists CGRP(8-37) and AM(22-52), the former antagonist, which is more selective for AM2 than AM1 receptors, being more effective than the latter one. Both antagonists were per se able to induce a slow, but significant decrease in the basal growth rate of DU-145 cells by inhibiting proliferation and enhancing apoptosis, again CGRP(8-37) being more effective than AM(22-52). Taken together, our findings allow us to suggest that: i) endogenous AM system plays an important autocrine-paracrine growth promoting action in the human prostate, being possibly involved in the development of the malignant phenotype of epithelial cells; and ii) the tumor promoting effect of AM in the human prostate is mainly mediated by the AM2 receptor (CRLR/RAMP3) subtype.


Assuntos
Perfilação da Expressão Gênica , Peptídeos/farmacologia , Peptídeos/fisiologia , Neoplasias da Próstata/genética , Neoplasias da Próstata/patologia , Receptores de Peptídeos/biossíntese , Adrenomedulina , Apoptose , Proliferação de Células , Transformação Celular Neoplásica , Humanos , Masculino , Fenótipo , RNA Mensageiro/análise , RNA Mensageiro/biossíntese , Radioimunoensaio , Receptores de Adrenomedulina , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Regulação para Cima
20.
Peptides ; 25(8): 1269-77, 2004 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-15350694

RESUMO

Ghrelin is an endogenous ligand of the growth hormone secretagogue receptor (GHS-R), two subtypes of which have been identified and named GHS-R1a and GHS-R1b. Evidence has been provided that ghrelin and its receptors are expressed in the adrenal gland, and we have investigated the possible role of the ghrelin system in the functional regulation of the human adrenal cortex. Reverse transcription-polymerase chain reaction detected the expression of both subtypes of GHS-Rs exclusively in the zona glomerulosa (ZG). Ghrelin did not significantly affect either basal or agonist-stimulated aldosterone secretion from cultured ZG cells. In contrast, ghrelin raised proliferative activity and decreased apoptotic deletion rate of ZG cells, the maximal effective concentration being 10(-8) M. The growth effects of 10(-8) M ghrelin on cultured ZG cells were not affected by either the protein kinase (PK)A and PKC antagonists H-89 and calphostin-C or the mitogen-activated PK (MAPK) p38 antagonist SB-293580, but were abolished by both the tyrosine kinase (TK) and MAPK p42/p44 antagonists tyrphostin-23 (10(-5) M) and PD-98059 (10(-4) M), respectively. Ghrelin (10(-8) M) enhanced TK and MAPK p42/p44 activities of ZG cells. Preincubation with 10(-5) M tyrphostin-23 blocked the ghrelin-induced stimulation of both TK and MAPK p42/p44, while preincubation with 10(-4) M PD-98059 only annulled MAPK p42/p44 stimulation. Collectively, our findings allow us to conclude that ghrelin, acting via GHS-Rs exclusively located in the ZG, enhances the growth of human adrenal cortex, through a mechanism involving the activation of the TK-dependent MAPK p42/p44 cascade.


Assuntos
Apoptose/efeitos dos fármacos , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Hormônios Peptídicos/farmacologia , Zona Glomerulosa/efeitos dos fármacos , Zona Glomerulosa/crescimento & desenvolvimento , Apoptose/fisiologia , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Grelina , Humanos , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Receptores Acoplados a Proteínas G/genética , Receptores Acoplados a Proteínas G/metabolismo , Receptores de Grelina , Zona Glomerulosa/citologia
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