[Retention of noradrenaline by the rat endometrial epithelium. Action of estradiol]. / Rétention de noradrenaline par l'épithelium d'endomètre de rat. Action de l'oestradiol

The application of the cytochemical fluorescence method on uterine samples obtained from spayed rats, injected with ascorbic acid, oestradiol, norspinephrine and oestradiol plus norepinephrine, permits the visualization of an extraneuronal uptake of norepinephrine by the luminal and glandular epithelium of the rat endometrium. The enhancing of the oestradiol uptake exerted by norepinephrine could be explained in this case by a direct action of norepinephrine on the target cell.

Interactions in the uptake between catecholamines and estradiol in the human uterus.

Optimal conditions of pH, dose, time and temperature for the in vitro uptake of radioactivity from 3-H-E or 3-H-NE by the human endometrium and myometrium were established. Uptake was dependent on temperature but not on pH. Uptake of radioactivity from 3-H-NE was always higher (p smaller than 0.05) in both tissues than the uptake of radioactivity from 3-H-E at all the studied times but 10 minutes. Only the uptake of radioactivity from 3-H-NE by the myometrium increased continuously from 2 to 90 minutes. E2 increased the uptake of radioactivity from 3-H-E and decreased the one from 3-H-NE, being both effects more significant (p smaller than 0.05) in the myometrium. Both E and NE increased significantly (p smaller than 0.05) the uptake of 3-H-E2 by the myometrium but not by the endometrium. These results indicate that the interactions between E and NE and E2 are more marked in the myometrium. The uterine tissues studied corresponded to the secretory phase of the menstrual cycle, which was established by the endometrial histology and plasma levels of progesterone.

Interactions of 17beta-estradiol and L-norepinephrine on the rat uterus.

Norepinephrine increased the in vitro uptake of 3H-estradiol by the uterus of spayed rats. This effect was observed at 15 and 30 min but not at 90 min. Norepinephrine also increased the binding of 3H-estradiol by the nuclear (p less than 0.02) and the cytosol fractions (p less than 0.01) when incubated with uterine homogenates, suggesting that norepinephrine does not require the presence of the intact tissue to exert its effects. The in vivo uptake of 3H-estradiol and the determination of the number of binding sites were performed in the uterus of rats treated with estradiol and estradiol plus norepinephrine. Norepinephrine alone increased the uptake of 3H-estradiol and the number of binding sites. The highest increment in both parameters was observed in the uterus of rats treated with estradiol plus norepinephrine. The estradiol Ka of the rat uterus cytosol treated with estradiol alone or plus norepinephrine was higher than that observed in the group without estradiol, suggesting the presence of different proteins that bind estradiol. These results indicate that norepinephrine increases the entrance of estradiol into the rat uterus both in vitro and in vivo.