M. Tébar

Centre d'Études et d'Expertise sur les Risques, l'Environnement, la Mobilité et l'Aménagement

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J. E. Sánchez‐Criado

Cordoba University

Antonio Ruíz

Universidad de Las Palmas de Gran Canaria

C. Bernal Bellido

Hospital Universitario Virgen del Rocío

José E. Sánchez‐Criado

University of Córdoba

D. Gónzalez

University of Córdoba

J. Th. J. Uilenbroek

Erasmus University Rotterdam

Guadalberto Hernández

Universidad de La Laguna

Frank H. de Jong

Diponegoro University

Francisco Gaytán

University of Córdoba

Rafaela Aguilar

University of Córdoba

Cooperative Institutions

Centre d'Études et d'Expertise sur les Risques, l'Environnement, la Mobilité et l'Aménagement

University of Córdoba

Laboratoire Aménagement Économie Transports

Erasmus University Rotterdam

Laboratoire Ville Mobilité Transport

Universitat Autònoma de Barcelona

Cordoba University

Boston Children's Hospital

Pediatrics and Genetics

Center for Northern Studies

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Hypothalamus-Pituitary-Ovarian Axis in Cyclic Rats Lacking Progesterone Actions1

Biology of Reproduction (1993)

José E. Sánchez‐Criado Francisco Galiot Carmina Bellido Dolores González M. Tébar

Antagonizing diestrous progesterone actions in cyclic rats by s.c. injections of the antiprogesterone RU486 (2 mg twice a day from metestrus through proestrus) increased LH and decreased FSH basal serum concentrations. Ovariectomy at metestrus (0800 h) increased serum levels of both gonadotropins in controls and reversed the RU486-induced dissociation of basal gonadotropin secretion. RU486-dissociated gonadotropin secretion is also dependent upon LHRH, since treatment (s.c.) with 1 mg GnRH antagonist (ORG 30276) twice a day on metestrus and diestrus completely prevented both the RU486-induced increase in LH and the decrease in FSH serum concentrations. The LHRH content in the medial basal hypothalamus and median eminence increased on proestrous morning in RU486-treated rats. The LH pituitary response to an exogenous i.v. bolus of 25 ng LHRH (Peninsula 7201; Peninsula Laboratory, Inc., Merseyside, UK) at 1700 h on diestrus was enhanced in rats treated with RU486. No differences in pituitary FSH response were noted with respect to oil-injected rats. The pituitary content of both gonadotropins decreased in RU486-treated rats on proestrous morning. All these effects due to RU486 in cyclic rats were reversed by ovariectomy. Testosterone serum levels increased significantly from diestrus onward, and the estradiol concentration increased on proestrous morning in RU486-treated rats. Ovariectomy as well as LHRH antagonist treatment eliminated the effects of RU486 on ovarian steroid production. Moreover, antiestrogen tamoxifen treatment reversed RU486-dissociated gonadotropin secretion, while antiandrogen flutamide treatment had no effect. The results of this experiment have confirmed previous findings that RU486 treatment dissociates basal gonadotropin secretion in cyclic rats. In addition, the present results show that: (1) this effect of RU486 is not due to a direct effect of this compound or to the blockade of progesterone action at a central level; (2) the effect of RU486 on pituitary gonadotropin secretion depends on ovarian substances other than progesterone and LHRH, since it is reversed by ovariectomy and completely abolished by LHRH antagonist treatment; (3) the reduction in FSH serum levels in rats treated with RU486 seems to be exerted by inhibin and estradiol at the pituitary level by reducing FSH synthesis and secretion; and (4) the hypersecretion of LH in rats treated with RU486, as compared to that resulting from ovariectomy, seems to be the consequence of, first, a lack of progesterone inhibitory action on LH secretion, and, second, an inappropriate feedback system involving increased hypothalamic LHRH activity and pituitary sensitivity to LHRH of moderately high levels of estradiol in the presence of abnormally high levels of testosterone.

Gonadotropin

Median eminence

Flutamide

10.1095/biolreprod48.4.916

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Citations (28)

Effect of RU486 injected on proestrous morning on LHRH, LH and 17beta-estradiol secretion during the estrous cycle in rat.

PubMed (1998)

M. Tébar Antonio Ruíz D. Gónzalez Guadalberto Hernández Rafael Alonso

Gonadotropin

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Comparison of the effects of antiprogestins RU38486, ZK98299 and ORG31710 on periovulatory hypophysial, ovarian and adrenal hormone secretion in the rat

Journal of Endocrinological Investigation (2000)

José E. Sánchez‐Criado M. Tébar C. Bernal Bellido Frank H. de Jong

10.1007/bf03343698

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Citations (8)

Ovary Mediates the Effects of RU486 Given during Proestrus on the Diestrous Secretion of Luteinizing Hormone in the Rat1

Biology of Reproduction (1996)

M. Tébar Antonio Ruíz C. Bernal Bellido José E. Sáchez-Criado

The aim of these experiments was to study the action of proestrous afternoon follicular progesterone secretion on the preovulatory secretion of gonadotropins in the rat. Four-day-cycling rats were given 4 mg of the antiprogestagen RU486 in the morning of proestrus (Day 1), and its effects on the pituitary function during diestrus were compared with those of RU486 given in the morning of estrus (Day 2). The pituitary function was assessed by measuring basal secretion of LH and FSH as well as the pituitary response to either estradiol benzoate (EB) (3 μg/100 g BW at 1300 h on Day 3) or LHRH (100 ng/rat at 1200 h on Day 4). In all experiments, trunk blood was taken at 1300 h on Day 4 to measure serum gonadotropin concentrations.

Basal (medicine)

Gonadotropin

10.1095/biolreprod54.6.1266

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Citations (10)

Mobilité en transitions : Connaître, comprendre et représenter

HAL (Le Centre pour la Communication Scientifique Directe) (2015)

M. Tébar Sophie Le Roux Damien Verry Irving Tapia Villareal Jean-Louis Valgalier

Parce qu'elles ont vu pour la premiere fois l'usage de la voiture stagner, les annees 2000 marquent un tournant dans l'histoire de la mobilite quotidienne. Cette evolution de nos societes est a inscrire dans un contexte marque par la transition numerique en cours, une transition environnementale que chacun appelle de ses voeux et l'augmentation des contraintes financieres pesant sur les menages et les acteurs publics. Issu d'un partenariat entre l'Ifsttar et le Cerema, cet ouvrage invite a explorer plus en avant les causes et les consequences de tels changements dans le contexte actuel. Pour cela, les methodes d'enquetes demandent a etre adaptees, les analyses approfondies et diversifiees et les outils d'aide a la decision repenses. C'est a ce triple exercice que ce travail, qui rassemble une quarantaine de contributions de chercheurs et techniciens des domaines de l'amenagement et des transports, se propose de contribuer.

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Antiprogestagen RU486 prevents the LH-dependent decrease in the serum concentrations of inhibin in the rat

Cellular and Molecular Neurobiology (1996)

M. Tébar C. Bernal Bellido J. Th. J. Uilenbroek J. E. Sánchez‐Criado

10.1007/bf02088096

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Citations (1)

Les individus se déplacent-ils différemment d’un jour sur l’autre ? Retour sur l’enquête GPS menée sur l’agglomération Toulousaine en 2023

Fabrice Hasiak M. Tébar Barbara Christian Fabienne Guillemot

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Unilateral ovariectomy, flutamide treatment and HCG reverse the anovulatory action of antiprogesterone RU486 in rat.

PubMed (1992)

M. Tébar Adrián Guzmán Sánchez J. E. Sánchez‐Criado

Administration of antiprogesterone RU486 (4 mg/day) from estrus through proestrus to cyclic rats blocked ovulation. Moreover, RU486 increased basal serum concentrations of LH, PRL, testosterone and estradiol, while it decreased basal serum concentration of FSH. Both unilateral ovariectomy and antiandrogen flutamide treatment, as well as an ovulatory injection of HCG in the proestrus afternoon partially reversed, the ovulatory blockade of RU486. These results indicate that both the decreased FSH concentration and the increased testosterone concentration, as well as the reduced ovulatory LH release are responsible for the anovulatory effects of RU486.

Flutamide

Basal (medicine)

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Citations (2)

Porfiria aguda intermitente y síndrome de secreción inadecuada de ADH

Revista Española de Anestesiología y Reanimación (2010)

M. Tébar Laura Aguilera

Porphobilinogen

Signs and symptoms

10.1016/s0034-9356(10)70233-4

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