Arrest of rat embryonic development by the inhibition of gamma-glutamyl transpeptidase. I. 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 endometrium (day 5 of pregnancy). Since gamma-GTP is an enzyme involved in the translocation of amino acids from fluids toward tissues, these substrates are necessary for anabolic processes.

METHODS AND RESULTS

The presence of statistically higher activity of gamma-GTP in rat (Sprague-Dawley) implantation sites (1.06 nmol/mg protein/min) than in nondecidualized (0.87 nmol/mg protein/min) tissues was demonstrated. The intrauterine administration of L-serine-borate complex (5 mM) during day 5 of pregnancy arrested 91.6% of rat embryonic development (day 18). This inhibitory effect was not present when borate or L-serine was administered separately. The L-serine-borate complex also inhibited (by 88%) the gamma-GTP in vitro.

CONCLUSION

The inhibition of gamma-GTP by L-serine-borate complex might be considered as a new approach to the arrest of biological processes in differentiation or development.