Sex-Associated Quantitative Differences in the Plasma Esterases of Inbred Mice

The presence of sex-associated quantitative differences in 4 of the plasma •esterases of C57BL/6 mice was determined using the zymogram technique with disc •electrophoresis in acrylamide gel. The levels •of 4 of the esterases are controlled by testos- terone and may be manipulated by hormone treatment, gonadectomy, or a combination of both. A testosterone-like effect of estradiol was also found in one of the esterase bands. No quantitative plasma esterase differences be- tween sexes were observed in prepubescent mice and no qualitative esterase differences were found between the sexes of adult mice of the same strain. (Endocrinology 78: 655, 1966) V ARIOUS reports have appeared in the literature concerning the protein and enzyme differences between the sexes in various species of animals. Dimopoullos and Schrader (1) have shown that male cattle have more /3-globulin and 7-globulin and less a-globulin glycoprotein than females. Espi- nosa et at. (2) have reported sex-associated differences in the alpha-1, alpha-2 and beta serum globulins of mice, while Bond (3) has demonstrated a protein in rat liver that is quantitatively under the control of testos- terone. Allen and Hunter (4) have shown that 5 esterases in the mouse epididymis are affected by testosterone. We (5) have re- cently shown that marked quantitative differences exist between the sexes of various strains of inbred mice in several of the ester- ases in mouse plasma separated by disc electrophoresis in acrylamide gel. Since these differences were not apparent in mice less than 3 weeks of age, a study of the effects of age and sex hormones was carried out in in- tact gonadectomized mice.