The activation of female sex hormones

Abstract

Addition of palmitic acid or stearyl alcohol to oestrone increases its duration of action in the oestrus test when given subcut. The threshold value and duration of oestrus obtained by 12 esters of oestrone administered by subcut. injection were detd. on the castrated rat. The threshold value increases according to the chain length of the acid groups; the duration of oestrus increases only up to oestrone-n-octanoate and then diminishes. The time course of the weight of the uterus after administration of oestrone and its esters was determined on young rats. The sequence of the esters as regards their activity is approximately the same as in the oestrus test. The maximum effect is attained in every case on the 4th day and the total duration of effect is approximately twice that found in the oestrus test. By planimetric measurement of the area bounded by the curves representing the increases of weight and the abscissa intercepting the starting point of the curve, the absolute output of activity, whose dimension is mg-, eg- or g-days, is ascertained. The efficiency coefficient (relative output of activity) obtained by esterification is expressed by the quotient of the output of activity of an ester and of that of the free hormone. The efficiency coefficients of various esters represent absolute and comparable values.