Hormone stéroïdienne

Résumé

Les hormones stéroïdiennes sont des stéroïdes se comportant comme des hormones. On peut les regrouper en cinq catégories selon leurs récepteurs : les glucocorticoïdes, les minéralocorticoïdes, les androgènes, les œstrogènes et les progestatifs. Les dérivés de la vitamine D forment un sixième système hormonal proche des précédents, mais techniquement parlant il s'agit de stérols plutôt que de stéroïdes. Principales hormones stéroïdiennes humaines naturelles

Les glucocorticoïdes ** le cortisol
Les minéralocorticoïdes ** l'aldostérone
Les stéroïdes sexuels ** Androgènes *** la testostérone *** la déhydroépiandrostérone (DHEA) *** le sulfate de déhydroépiandrostérone (DHEAS) *** l'androstènedione *** la dihydrotestostérone (DHT) ** Les œstrogènes *** l'estradiol *** l'estrone *** l'estriol ** Les progestatifs *** la progestérone

Stéroïdogenèse Les hormones stéroïdiennes sont toutes synthétisées à partir du cholestérol dans un processus appelé stéroïdogenèse

Source officielle

https://fr.wikipedia.org/wiki/Hormone_st%C3%A9ro%C3%AFdienne

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Cholesterol is a very crucial lipid for animal cells, since it is the building block of cellular membranes, control fluidity of membranes, regulate intracellular transport, cell signalling, nerve conduction and serve as a precursor for synthesis of vitamin D and steroid hormones. Cholesterol is such an important biological molecule for animal cells, yet it has been a real challenge so far, to understand distribution of cholesterol within the biological membranes. In our study, using ultra-high resolution ion microprobe (NanoSIMS) imaging enables us to detect incorporated cholesterol in cells, introduced as 13C labeled cholesterol, in nanometer scale. Then, we are able to monitor the localization of detected cholesterol in cellular structures by combining NanoSIMS (Secondary Ion Mass Spectrometry) with electron microscopy. Our aim in this study is to determine level of incorporated cholesterol in cellular membranes, secretion and endocytic systems, by the help of NanoSIMS imaging combined with electron microscopy.

2015

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Monitoring the Cellular Cholesterol Distribution via nanoSIMS Imaging

Mustafa Demir

Cholesterol is a very important lipid, manufactured by all animal cells for their use. About 20-25% of total daily cholesterol production occurs in the liver; other sites that have higher synthesis rate are intestine, adrenal glands and reproductive organs. It is not only produced in the body cells but also it can be obtained from dietary sources as well. Presence of cholesterol is very crucial for animal cells, since it is the building block of cellular membranes provide membrane fluidity over the range of physiological temperatures; within the cell membrane, it also functions to regulate intracellular transport, cell signaling and nerve conduction. Moreover, it is a precursor for synthesis vitamin D and and steroid hormones. Cholesterol is such an important biological molecule for animal cells, yet it has been a real challenge so far, to understand distribution of cholesterol within the biological membranes. In our study, via using 13C labeled cholesterol, we are able to monitor incorporated cholesterol in cellular structures, with the help of combination of Electron Microscopy imaging and nanoSIMS imaging. Our aim in this study is to address a really fundamental question, what is the distribution gradient of cholesterol, through different layers of cellular membranes.

2015

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No Scope for Social Modulation of Steroid Levels in a Year-Round Territorial Damselfish

Katarina Damjanovic

Both latitude and mating system have been proposed to shape relationships between steroid hormone levels and social behavior. Recently it has been postulated that species with long lasting non-seasonal territorial behavior have low androgen responsiveness. Tropical damselfishes are an ideal family to test this proposition because they show a large variety in mating systems. Here we contribute to the comparative dataset by measuring the response in steroid levels after social modulation in the banded sergeant, Abudefduf septemfasciatus, a species with non-seasonal territoriality. In highly territorial and brooding males, we found low androgen and cortisol levels that did not increase after experimental intraspecific simulated territorial intrusions (STI tests). No relationship was found between the variation in steroid hormone levels and territorial responses to naturally occurring territorial intrusions. Although steroid levels were low, male A. septemfasciatus were highly territorial both to STI challenges and to fishes that passed the territory. They often chased intruders for several meters away from the territory. This indicates that during nest defence in a non-seasonal territorial damselfish species, territorial behaviors are shown independent of variation in androgen and cortisol levels. J. Exp. Zool. 323A: 80-88, 2015. (c) 2014 Wiley Periodicals, Inc.

Wiley-Blackwell2015

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