EFFECTS OF VARIOUS HORMONAL CONDITIONS IN THE INTACT RAT ON THE SYNTHESIS OF SERUM CHOLINESTERASE11

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Abstract
Nonspecific cholinesterase is many tunes more concentrated in the serum of mature [male] rats than in [male] serum. Enzymic activity was measured by a microchemical titrimetric method, and the sera of some individual rats were followed for as long as 1 1/2 yrs. Certain long-term trends in enzyme level were noted in the sera of normal [female] [female] , but no short-term fluctuations were observed which could be correlated with stages of the estrous cycle. Conditions in the intact [female] rat in which the serum enzyme levels are high are also conditions in which relatively high and continuous estrogen levels are known or extremely probable: (1) spontaneous or light-induced per-sistent-estrus, (2) the last half of pregnancy, and (3) pseudo-pregnancy induced by injecting estrogen. Conditions in which the enzyme level is depressed are those in which low estrogen levels are probable : (1) the first half of pregnancy, (2) psuedo-pregnancy induced by sterile mating or by the daily admn. of progesterone, (3) the post partum state without lactation (moderate depression), and (4) lactation (extreme depression). Serum cholinesterase therefore appears to parallel estrogen level but to be independent of progesterone level. Estrogen does not affect the activity of cholinesterase directly; rather, the hormone stimulates synthesis of the enzyme.