ARREST OF RAT EMBRYONIC-DEVELOPMENT BY THE INHIBITION OF GAMMA-GLUTAMYL-TRANSPEPTIDASE .1. INTRAUTERINE ADMINISTRATION OF L-SERINE-BORATE COMPLEX

Objective-The purpose of this study was to investigate the activity of gamma-glutamyl transpeptidase (gamma-GTP, E.C. 2.3.2.2) in rat endome trium (day 5 of pregnancy). Since gamma-GTP is an enzyme involved in t he translocation of amino acids from fluids toward tissues, these subs trates are necessary for anabolic processes. Methods and Results-The p resence of statistically higher activity of gamma-GTP in rat (Sprague- Dawley) implantation sites (1.06 nmol/mg protein/min) than in nondecid ualized (0.87 nmol/mg protein/min) tissues was demonstrated. The intra uterine administration of L-serine-borate complex (5 mM) during day 5 of pregnancy arrested 98.6% of rat embryonic development (day 18). Thi s inhibitory effect was not present when berate or L-serine was admini stered separately. The L-serine-borate complex also inhibited (by 88%) the gamma-GTP in vitro. Conclusion-The inhibition of gamma-GTP by L-s erine-borate complex might be considered as a new approach to the arre st of biological processes in differentiation or development.