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Biomedical subjects

F Piva

Publications and source records attributed to F Piva.

80 records · Page 5Linked to original sources
PubMed1968

Brain receptors sensitive to indole compounds: function in control of luteinizing hormone secretion.

The placement of melatonin and of 5-hydroxytryptophol in the median eminence of castrated male rats is followed 5 days later by a significant decrease in pituitary stores of luteinizing hormone. Pituitary reserve of this hormone is also depleted after the implantation of melatonin, 5-hydroxytryptophol, and 5-methoxytryptophol in the reticular formation of the midbrain. It is suggested that these indole compounds, which are normally synthesized in the pineal gland, may intervene in the control of the secretion of luteinizing hormone, possibly by acting on specific receptors localized in the median eminence and in the midbrain.

Animals↗
PubMedDate not supplied

Effects and metabolism of steroid hormones in human neuroblastoma cells.

The development of the central nervous system is influenced by sex steroids and by their metabolites. However, little information on the possible effects of steroid hormones on neuroblastoma cells is available. Human neuroblastoma cell lines have been used as a model of human neuroblasts in vitro to study the metabolism of steroid hormones; in addition, the effects of steroids and steroid antagonists on neuroblastoma cell growth have also been investigated. The results obtained show that SH-SY5Y human neuroblastoma cells may actively metabolize testosterone and progesterone to their respective 5 alpha-reduced metabolites and that differentiation of neuroblastoma cells is paralleled by a significant increase in expression of the type-1 5 alpha-reductase and of the formation of steroid metabolites. All these data are suggestive of a potential role of steroid 5 alpha-reduced metabolites in the biology of neuroblastoma cells. Studies performed to analyze the role of steroid hormones on neuroblastoma cell proliferation show that progesterone at low doses may induce minor stimulation, and at higher doses, a toxic effect on the neuroblastoma cell line SK-N-SH is seen. Moreover, the antiprogestin 17 beta-hydroxy-11 beta-(4-dimethylamino-phenyl-1)-17-(prop-1-ynyl)estra-4,9-dien+ ++-3-one (RU486) decreases the proliferation of these cells in a dose-dependent manner. The effect of RU486 is not antagonized by either progesterone or dexamethasone, a result that seems to exclude the action of RU486 via classic intracellular steroid hormone receptors.

Cell Division↗
PubMedDate not supplied

Effects of steroid hormones on gene expression of glial markers in the central and peripheral nervous system: variations induced by aging.

The present article summarizes our data regarding: (a) the effect of sex steroids on the expression of a specific astrocytic marker in glial cell cultures (GFAP); (b) the effects of aging on two markers of the peripheral myelin (glycoprotein Po and the myelin basic protein, MBP); (c) the possible modification of the damaging effects of aging on these two markers by the in vivo administration of progesterone and its derivatives; and, finally, (d) the effect of progesterone derivatives on the gene expression of Po in cultures of rat Schwann cells. The data obtained have indicated that progesterone and its 5 alpha-reduced metabolites may play an important role in the control of gene expression of GFAP and Po, respectively, in type 1 astrocytes and Schwann cells. It has also been found that the gene expression of Po and MBP is dramatically decreased in the myelin of the sciatic nerve of aged male rats and that the aged-linked decrease of the gene expression of Po is partially reversible with steroid treatment.

Aging↗
PubMedDate not supplied

Mechanism of action of interleukin-1 in modulating gonadotropin secretion. In vivo and in vitro studies.

To obtain further information on the mode of action of interleukin (IL)-1 in modulating gonadotropin secretion, a series of in vivo and in vitro studies has been performed with the beta-isoform of IL-1. IL-1 beta injected in a lateral ventricle of 3-week-castrated female rats resulted in the expected decrease in serum levels of gonadotropins luteinizing hormone (LH), and follicle-stimulating hormone (FSH), accompanied by a decrease in the number of LH-releasing hormone (LHRH) receptors. These results may indicate that the inhibition of gonadotropin release may result from a decrease in the number of LHRH pituitary receptors either through a direct effect on the pituitary or by modulating the release of LHRH from hypothalamic neurons able to induce a reduction in pituitary LHRH receptors. In vitro studies using the GT1-1 cell line, which specifically produces and secretes LHRH, demonstrated that IL-beta stimulates LHRH release but does not influence intracellular levels of LHRH mRNA. These results seem to indicate that IL-1 beta may act at several levels of the nervous machinery leading to gonadotropin secretion, with a series of effects more complex than previously anticipated.

Animals↗