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Your search keyword '"Vallarino, Mauro"' showing total 153 results
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153 results on '"Vallarino, Mauro"'

15. Preface

Author

Coast, Geoffrey M., Roubos, Eric W., Vallarino, Mauro, and Vaudry, Hubert

Published
2009
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43. Immunohistochemical localization and biological activity of the steroidogenic enzyme cytochrome P450 17α-hydroxylase/C17, 20-lyase (P450C17) in the frog brain and pituitary.

Author

Do Rego, Jean Luc, Tremblay, Yves, Luu-The, Van, Repetto, Emanuela, Castel, Hélène, Vallarino, Mauro, Bélanger, Alain, Pelletier, Georges, and Vaudry, Hubert

Subjects
BRAIN mapping, STEROIDS, ENZYME activation, CYTOCHROME P-450, HYDROXYPROGESTERONE, ANDROSTENEDIONE, TELENCEPHALON, MESENCEPHALON
Abstract

It is now clearly established that the brain has the capability of synthesizing various biologically active steroids including 17-hydroxypregnenolone (17OH-Δ5P), 17-hydroxyprogesterone (17OH-P), dehydroepiandrosterone (DHEA) and androstenedione (Δ4). However, the presence, distribution and activity of cytochrome P450 17α-hydroxylase/C17, 20-lyase (P450C17), a key enzyme required for the conversion of pregnenolone (Δ5P) and progesterone (P) into these steroids, are poorly documented. Here, we show that P450C17-like immunoreactivity is widely distributed in the frog brain and pituitary. Prominent populations of P450C17-containing cells were observed in a number nuclei of the telencephalon, diencephalon, mesencephalon and metencephalon, as well as in the pars distalis and pars intermedia of the pituitary. In the brain, P450C17-like immunoreactivity was almost exclusively located in neurons. In several hypothalamic nuclei, P450C17-positive cell bodies also contained 3β-hydroxysteroid dehydrogenase-like immunoreactivity. Incubation of telencephalon, diencephalon, mesencephalon, metencephalon or pituitary explants with [3H]Δ5P resulted in the formation of several tritiated steroids including 17OH-Δ5P, 17OH-P, DHEA and Δ4. De novo synthesis of C21 17-hydroxysteroids and C19 ketosteroids was reduced in a concentration-dependent manner by ketoconazole, a P450C17 inhibitor. This is the first detailed immunohistochemical mapping of P450C17 in the brain and pituitary of any vertebrate. Altogether, the present data provide evidence that CNS neurons and pituitary cells can synthesize androgens. [ABSTRACT FROM AUTHOR]

Published
2007
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49. In the African Lungfish Met-Enkephalin and Leu-Enkephalin Are Derived from Separate Genes: Cloning of a Proenkephalin cDNA.

Author

Dores, Robert M., Lee, Jenny, Sollars, Cristina, Danielson, Phillip, Lihrmann, Isabelle, Vallarino, Mauro, and Vaudry, Hubert

Subjects
ENKEPHALINS, LUNGFISHES, OPIOIDS, GENES, PHYLOGENY
Abstract

A full-length proenkephalin cDNA (accession number: AF232670) was cloned from an African lungfish (Protopterus annectens) brain cDNA library. The 1,351-bp African lungfish proenkephalin contains an open reading frame that codes 266 amino acids and a stop codon. Within the sequence of lungfish proenkephalin there are 5 pentapeptide opioid sequences (all YGGFM), 1 octapeptide opioid sequence (YGGFMRSL) and 1 heptapeptide opioid sequence (YGGFMGY). A Leu-enkephalin sequence was conspicuously absent in lungfish proenkephalin. These results, coupled with observations on the organization of amphibian proenkephalin and mammalian proenkephalin, indicate that among the Sarcopterygii (lobed finned fish and tetrapods), the appearance of a Leu-enkephalin sequence in proenkephalin may have evolved in either the ancestral amniotes or the ancestral mammals, but not earlier in sarcopterygian evolution. Furthermore, the detection of neurons in the lungfish CNS that are only immunopositive for Met-enkephalin, coupled with earlier anatomical studies on the presence of neurons in the lungfish CNS that are only immunopositive for Leu-enkephalin, indicates that a Leu-enkephalin-coding opioid gene must be present in the CNS of the lungfish. This gene may be the lungfish form of prodynorphin. Given the phylogenetic position of the lungfish in vertebrate evolution, the putative Leu-enkephalin-coding gene must have evolved in the ancestral sarcopterygian vertebrates, or in the ancestral gnathostomes. The apparent slow rate of lungfish evolution makes these organisms interesting models for investigating the evolution of the opioid/orphanin gene family.Copyright © 2000 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Published
2000
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