Glycerylphosphorylcholine diesterase activity of uterine fluid in conditions inducing secondary sex ratio change in the rat.

Food restriction or decreasing the ratio of [Na+, K+] to [Ca++, Mg++] in the diet of female rats before conception favoured the production of female offspring. Seven days of food deprivation decreased uterine fluid GPC diesterase activity in female rats, whereas long-term food restriction (21 days), rather than decreasing the enzyme activity, apparently stimulated it. Dietary Ca and Mg supplementation, likewise, produced significant decrease in GPC diesterase activity. A significantly positive correlation was observed between the levels of uterine GPC diesterase and secondary sex ratio change, which indicates that these dietary techniques of sex-ratio manipulation may modulate the uterine fluid GPC diesterase activity and influence sex determination in utero.