Effect of corticosterone, hydrocortisone and prostaglandin fatty acid precursors on the spontaneous motility of the uterus isolated from ovariectomized rats.

The effect of corticosterone (CC, 0.4 and 1 microgram/ml) and of hydrocortisone (HC, 20 and 40 micrograms/ml) on the spontaneous motility and on prostaglandin (PG) generation in the uterus from ovariectomized rats, was studied. Both concentrations of CC depressed significantly the frequency of contractions but the isometric developed tension was affected only by the higher dose. HC significantly inhibited the isometric developed tension at both concentrations whereas the contractile frequency was only depressed by the higher one. The CC-inhibited motility was accompanied by a reduction in the amount of PGs released from the uterus into the bath solution. In addition, the influences of arachidonic acid (AA), linoleic acid (LA) and gamma-linolenic acid (alpha-LA) - 1 or 2 micrograms/ml - on the depression evoked by CC, were also explored. The fatty acids had no effect on the spontaneous uterine motility except in the case of alpha-LA at 1 microgram/ml. alpha-LA completely blocked the CC-evoked reduction of both tension and frequency; AA (1 microgram/ml) elicited a reversion only on frequency whereas LA had no effect at all. This reversion by a fatty acid PG-precursor might indicate that CC is able to diminish substrate availability for PG synthesis in the rat uterus.