Effects of sexual hormones on gonadotrophin secretion in prepuberal female rats

Resumen Los estrógenos ejercen sobre la rate hembra un efecto de retroalimentación negativo sobre la secreción de gonadotrofinas a los 20 días de edad y un efecto positivo a los 28 días de edad. La testosterona inhibió la secreción de gonadotrofinas en ratas de 20 días, pero no tuvo efecto a los 28 días de edad. En los animales androgenizados al nacer ambas hormonas inhiben la secreción de gonadotrofinas a los 20 y a los 28 días de edad.

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Supported by a grant from the Consejo Nacional de Investigaciones Científicas y Técnicas. Repùblica Argentina.     

Effects of estrogen or progesterone on prepuberal ovaries implanted in castrated adult male rats

Résumé Des greffons d'ovaire de rat impubère placés dans la chambre antérieure de l'il du mâle castré, après traitement avec 0,5 mg de dipropionate d'stradiol ou avec deux doses de 1 mg de progestérone, ont montré une évidente ovulation. On interprète ce fait comme dû á l'action des hormones injectées dans le système nerveux central et qui favorisent le mécanisme de l'ovulation.     

Bone marrow in male and female rats

Summary Sex differences of high significance in the marrow weight relative to femur volume, as well as to body weight, were found in adult rats. A positive significant correlation was found between the femur volume and the marrow volume in both sexes, while a negative significant correlation between femur density and the marrow content (mg/mm³) exists only in male rats.     

Effects of multiple injections of luteinizing hormone-releasing hormone on the induction of pregnancy in androgenized female rats

A study of the effect of cyclic (every 4 days) administration of gonadotropin releasing hormone on reproductive performance of the androgenized female rat was carried out. The responses measured were indirect indices of increased gonadotropin output; ovulation rate, uterine decidualization, mating and implantation.     

Hyperthyroidism and gonadotropin secretion in male and female rats

Résumé Chez des rats adultes, mâles et femelles, traités à la triidothyronine (T₃), on a remarqué une perte de poids qui n'est pas dûe à une diminution de consommation de nourriture. Les niveaux sériques de l'hormone lutéinisante semblent être réduits par le traitement au T₃ chez les rats femelles, mais non pas chez les rats mâles. Le niveau sérique de l'hormone stimulante de la follicule et le niveau pituitaire de gonadotropines ne sont pas affectés de façon significative par le traitement au T₃.

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Acknowledgments. This work was supported by grant No. A-6248 from the National Research Council of Canada. The authors are grateful to Dr.G. D. Niswender, Dr. L. E. Reichert Jr. and the National Institute of Arthritis and Metabolic Diseases Rat Pituitary Hormone Program for providing the materials used in the radioimmunoassays.     

Effects of multiple injections of luteinizing hormone-releasing hormone in the induction of pregnancy in androgenized female rats

Summary A study of the effect of cyclic (every 4 days) administration of gonadotropin releasing hormone on reproductive performance of the androgenized female rat was carried out. The responses measured were indirect indices of increased gonadotropin output; ovulation rate, uterine decidualization, mating and implantation.     

Luteinizing hormone content of the pars tuberalis of the hypophysis of neonatally androgenized female rats

Summary The immunoreactive LH content of the pars tuberalis of neonatally androgenized female rats was studied and found to be significantly lower than that of control females at oestrus or of control males. It is concluded that the rat pars tuberalis does secrete LH and that this secretory activity is diminished by neonatal androgenization in a manner that differs from that reported for the LH secretion in the pars distalis.This investigation received financial support from Direccion de Investigacion, grants RMS-80-13 and S-80-26, Universidad Austral de Chile.     

Effect of estradiol on aminoacid incorporation into proteins of different hypothalamic areas in prepuberal rats

Summary Estradiol in vitro produces a significant increase in the incorporation of³H-leucine into proteins of the anterior hypothalamic area in prepuberal female rats, 15 and 20 days old, but not in younger animals. The ovarian hormone induced no changes in the protein synthetic activity of middle and posterior hypothalamus and cerebral cortex in prepuberal female rats of different ages. Estradiol did not modify the protein synthesis of the hypothalamus and cerebral cortex in prepuberal male rats.Supported by a grant from the Consejo Nacional de Investigaciones Cientifícas y Técnicas de la República Argentina.     

Effect of estradiol on aminoacid incorporation into proteins of different hypothalamic areas in prepuberal rats.

Estradiol in vitro produces a significant increase in the incorporation of 3H-leucine into proteins of the anterior hypothalamic area in prepuberal female rats, 15 and 20 days old, but not in younger animals. The ovarian hormone induced no changes in the protein synthetic activity of middle and posterior hypothalamus and cerebral cortex in prepuberal female rats of different ages. Estradiol did not modify the protein synthesis of the hypothalamus and cerebral cortex in prepuberal male rats.     

Oxidative metabolism of the limbic system in androgenized rats

Resumen Se ha estudiado el metabolismo oxidativo de amígdala e hipocampo en ratas en fase de estro, diestro y androgenizadas postnatalmente con testosterona. En estos animales desaparecen las variaciones observadas en animales cíclicos, presentando unos valores semejantes a los de diestro.     

The protective effect of estrogens against spontaneous pancratic islet and renal changes in aging male rats

Zusammenfassung Langzeitbehandlung mit Oestrogen bei von früher Jugend an daran gewöhnten männlichen Ratten ergibt einen vollständigen Schutz gegen Spontanfibrosis der Langerhansschen Inseln und ist ebenso wirksam gegen senile Nierenveränderungen.     

Oxidative metabolism of the limbic system in prepuberal rats

Resumen El consumo de oxígeno por amigdala, en ratas prepúberes, es mayor en machos que en hembras, hembras tratadas en el día 5° con propionato de testosterona y machos castrados postnatalmente. En los machos prepúberes, la castración origina una disminución en el consumo de oxígeno por amígdala.     

Splenic thymidine kinase and DNA during early postnatal development of the androgenized female rat

Administration of a pharmacologic dose of testosterone propionate to neonatal female rats had no effect on either thymidine kinase activity or DNA synthesis in the spleen during the first 3 postnatal weeks.