Estrogen (EB) and EB + Progesterone (P) Induced Changes in Pituitary Sodium, Potassium Adenosine Triphosphatase Activity (ATPase)

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Abstract
Estradiol-benzoate (EB) injected into previously ovariecto-mized (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.