Metabolism of C21 steroids by incubated adrenals of ACTH treated rats

Resumen En animales tratados crónicamente con ACTH se aumentan o activan los sistemas de la adrenal que catabolizan la corticosterona y los que hidroxilan en C²¹, a la vez que disminuye la cantidad de radioactividad incorporada a la 18 OH DOC. Esto indica que el ACTH in vivo tiene sobre la adrenal incubada una acción distinta, a veces opuesta, a la del ACTH exógeno agregado in vitro al principio de la incubación.

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This investigation was supported by U.S.P.H.S. grant No. 1-RO5-TWO0200-01.     

Effect of progesterone on human corticosteroid 21-hydroxylation.

Progesterone inhibits the 21-hydroxylation of 17alpha-hydroxyprogesterone by human adrenal cortex microsomes. The possible light this finding may shed on the genetic condition, the 'adrenogenital syndrome' is discussed. Km and Vmax data for the above hydroxylation reaction are given.     

Inhibition of testosterone biosynthesis by medrogestone

Résumé In vitro, la medrogestone bloque la synthèse des hormones dans les gonades par inhibition de la 3-hydroxystéroide ^4,5-isomérase. In vivo, la medrogestone réduit le niveau de testostérone dans le testicules de rat.

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We wish to thank Mrs.S. gosselin, Miss N. Jagarinec andMrs. F. Fitzsimons for their technical assistance andDr. G. Schilling for analyses by gas-liquid chromatography.     

Modification of visual signals by nigral stimulation

Summary Responses of the lateral geniculate neurons to light were modified by stimulation of the substantia nigra. Nigral stimulation often caused enhancement of firing in neurons responding primarily to flash, but it usually had the contrary effect on units inhibited by light.     

Inhibition of shivering obtained by peripheral stimulation

Résumé La stimulation de la patte chez le chien anesthésié, inhibe l'activité musculaire enregistrée pendant les attaques de frisson. Cet effet peut dépendre de l'action inhibitrice des influx nerveux agissant sur l'hypothalamus ou même sur la formation réticulaire, et peut se distinguer des influences inhibitrices d'origine médullaire qu'on observe quand la patte est stimulée en dehors des attaques de frisson.

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Supported by grants from the British Council and the Consejo Nacional de Investigaciones Cientificas y Técnicas, Argentina.