The influence of oestradiol-17-beta on the rat uterine Na+, K+-Mg++ activated adenosine triphosphatase activity

The influence of the estrous cycle on the accumulation of 3H-noradrenaline in rat uterus and on efflux of radioactivity from the uterus

Groups of female rats were used throughout the 4-days estrous cycle and the accumulation of noradrenaline and its efflux were studied after incubation with the labelled amine. Comparisons were made between uterine horns corresponding to each one of the 4 stages of the cycle, i.e., diestrus, proestrus, metestrus and estrus. Accumulation in diestrus reached the highest value, which was 1.64-fold higher than in estrus. An estimate of the original distribution of the amine into the extraneuronal and neuronal compartments of the tissue was obtained by compartmental analysis of the efflux curves. Size and half times of neuronal and extraneuronal compartments showed some relationship with the stage of the cycle.

Estrogen (EB) and EB + progesterone (P) induced changes in pituitary sodium, potassium adenosine triphosphatase activity (ATPase)

Estradiol-benzoate (EB) injected into previously ovariectomized (OVX) rats, increased pituitary ATPase activity 69% over controls, within one hour of treatment. Twelve hours after injection, ATPase activity was not significantly different from controls. Progesterone [(P): 5mg/100gBW] administered in conjunction with EB elicited an analogous response. AT at time of EB and EB+P induced increments in pituitary ATPase activity, plasma LH levels were dramatically reduced to normal, intact diestrous control levels. Post-castrational elevations in FSH were also suppressed after one hour of treatment with EB, but not following EB+P administration. The results suggest that the inhibitory actions of EB and EB+P on post-castrational LH levels may be related to modulation by these steroids of pituitary membrane ATPase activity.