Anti-oestrogen modification of uterine responses to oestrogen in the rat

Abstract

Oestradiol (single injection) resulted in a peak in uterine blood flow 3 h later with a secondary rise in blood flow at 30 h. Uterine wet and dry weights increased more slowly and were still above control values 24 h after the injection. If a second injection of oestradiol was given 24 h after the first then uterine blood flow was again maximal at 3 h but remained at this level for a further 3 h, probably due to the secondary rise induced by the first injection. Uterine wet weight was further increased by the second injection of oestradiol but the effect did not occur until 6 h after the oestrogen treatment. Pretreatment with an anti-oestrogen, tamoxifen or nafoxidine, inhibited or reduced significantly the uterine weight and uterine blood flow responses to oestrogen but increased uterine weights and produced some increase in uterine blood flow when given alone. It is suggested that both blood flow and weight responses to oestrogen in the uterus are mediated through the oestrogen receptors.

Oestrogenic rhythm induced by a single administration of the extract of Ferula jaeschkeana to immature rats

“…Sheehan et al (1981) have reported that in immature rats a single oestrogen injection initiates a complex set of biochemical responses culminating at 24 to 36h in uterine growth. Single administration of oestradiol causes an increase in the uterine wet and dry weights (Majid and Senior, 1982) which may be due to the stimulation of protein synthesis via receptor activation in the nuclear and cytoplasmic compartments after 24 h of its administration (Mukku et al, 1981;Waters and Knowler, 1981). The hexane extract of F. jaeschkeana exhibits potent oestrogenic activity in immature rats (Pathak and Prakash, 1989).…”

Modification of the rat uterine response to oestrogen and tamoxifen by thromboxane antagonists

“…This dose of oestradiol was chosen as it gives maximal uterine blood flow 3 h after administration and is the minimum dose to produce this effect. Tamoxifen (ICI, Macclesfield, Cheshire) was dissolved in ethanol and dispersed in arachis oil before subcutaneous (s.c.) injection, 24 h before measurements were made, at a dose level of 1 mg kg'-as previously described (Majid & Senior, 1982). Serum levels of tamoxifen have also been shown to peak at this time (Bowman et al, 1982).…”