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P Rebuffat

Publications and source records attributed to P Rebuffat.

115 records · Page 7Linked to original sources
PubMedDate not supplied

Effects of substance P on the rat adrenal zona glomerulosa in vivo.

Substance P (SP) acutely enhanced the plasma concentration of aldosterone in rats whose hypothalamo-hypophyseal-adrenal axis and renin-angiotensin system were pharmacologically interrupted. The maximal response was obtained with a dose of 100 micrograms/kg. A prolonged (7 days) subcutaneous infusion with SP (50 micrograms/kg/hr) caused a notable hypertrophy of zona glomerulosa cells associated with significant rises in both basal and angiotensin-stimulated plasma levels of aldosterone. Zona fasciculata and the blood concentration of corticosterone were not affected. These findings suggest that SP is specifically involved in the stimulation of the growth and secretory activity of the rat zona glomerulosa.

Adrenocorticotropic Hormone↗
PubMedDate not supplied

Effects of prolonged infusion with endothelin-1 on the function and morphology of rat adrenal cortex.

A week of SC infusion with endothelin-1 (ET-1) (0.2 microgram.kg-1.hr-1) lowered PRA and raised plasma aldosterone (A) concentration in rats. Kalaemia and the plasma levels of ACTH and corticosterone (B) were not affected. Prolonged ET-1 administration caused a notable hypertrophy of zona glomerulosa (ZG) and its parenchymal cells, without inducing any apparent change in zona fasciculata. Stereology showed that ZG cell hypertrophy was mainly due to the increase in the volume of the mitochondrial compartment and to the proliferation of smooth endoplasmic reticulum (i.e., the two organelles in which the enzymes of steroid synthesis are contained). Isolated ZG cells from ET-1-infused animals evidenced a notable enhancement in their basal production of A and B. The secretory responses of ZG cells to the maximal effective concentrations of their three main stimulators (ACTH, angiotensin-II and K+) displayed comparable increases. These findings indicate that ET-1, when chronically administered, is able to specifically enhance the growth and steroidogenic capacity of rat ZG, and suggest that the mechanism underlying this ET-1 effect involves stimulation of the de novo synthesis of both the steroidogenic enzymes and the membrane framework in which they are located.

Adrenal Cortex↗
PubMedDate not supplied

Stimulatory effect of the substance P antagonist spantide-II on aldosterone secretion of dispersed rat zona glomerulosa cells.

Substance P (SP) did not affect either basal or agonist-stimulated aldosterone production by dispersed rat zona glomerulosa (ZG) cells. In contrast, the SP-receptor antagonist spantide-II (SPA), at 10(-8)/10(-6) M concentrations, markedly raised basal and 10(-9) M ACTH, but not 10(-9) M angiotensin II-stimulated aldosterone secretion. The secretagogue effect of 10(-6) M SPA was annulled by SP (10(-6) M) and the protein kinase (PK)-C inhibitor Ro31-8220 (10(-6) M), but was unaffected by the PKA inhibitor H-89 (10(-5) M). In light of these findings the following conclusions can be drawn: (i) SP does not exert a physiologically relevant direct modulatory action on aldosterone secretion of rat ZG cells; (ii) a receptor-independent inhibitory interaction is likely to occur between SP and SPA molecules; and (iii) SPA activates, through a receptor-independent mechanism, phosphoinositide signaling pathway in rat ZG cells.

Aldosterone↗
PubMedDate not supplied

Adrenocortical oncocytoma: case report and review of the literature.

Only 9 oncocytic neoplasms of true adrenal origin have been described to date. It therefore seemed of interest to study the histochemical and ultrastructural features of a non-functioning monolateral adrenocortical oncocytoma which was incidentally detected by ultrasonography and magnetic resonance imaging in a 28-year-old woman. The tumor was round, well encapsulated and weighed 73 g. It consisted of islets of eosinophilic cells, and did not display any sign of necrosis. The proliferation rate (as evaluated by mitotic index and percentage of MIB-1 Ki67 positive cells) was low, and atypic mitoses were absent; some rare cells with nuclear atypias were observed and the capsule was focally invaded by oncocytes. Immunocytochemistry did not show expression of vimentin or cytokeratin. The oncocytes had an abundant cytoplasm packed with mitochondria containing plate-like cristae. Smooth endoplasmic reticulum was virtually absent, while rough endoplasmic reticulum cisternae and free ribosomes were abundant. Although the classic histological approach clearly indicates the benign nature of the tumor, the immunocytochemical and ultrastructural features of oncocytes may suggest their potential for malignant behavior.

Adenoma, Oxyphilic↗
PubMedDate not supplied

Long-term trophic action of alpha-melanocyte-stimulating hormone on the zona glomerulosa of dexamethasone -or captopril-treated rats, with or without maintenance doses of ACTH or angiotensin. II: Stereology and plasma hormone concentrations.

The effects of a long-term (7 days) administration of alpha-melanocyte-stimulating hormone (alpha-MSH) on the zona glomerulosa were investigated in "normal" rats and in animals in which the hypothalamic-hypophyseal-adrenal axis and the renin-angiotensin system had been pharmacologically interrupted. alpha-MSH caused a notable hypertrophy of the zona glomerulosa and its parenchymal cells, as well as a significant increase in the plasma concentration of aldosterone, in rats infused with dexamethasone, dexamethasone plus ACTH or captopril plus angiotensin II, but not in animals treated with captopril alone. These findings indicate that alpha-MSH is directly involved in the stimulation of the growth and steroidogenic capacity of rat zona glomerulosa, and that this action of alpha-MSH requires a normal level of circulating angiotensin II.

Adrenocorticotropic Hormone↗