A synthetic GNRH agonist; binds to GNRHR (Ki = 0.2 nM in CHO cells expressing the human receptor); stimulates oxytocin and vasopressin release ex vivo from the isolated rat hypothalamo-neurohypophysial system (100 nM); initial dose of 100 μg stimulates acute increases in LH, FSH, and testosterone serum levels (50-, 2.5-, and 15-fold, respectively), while chronic treatment leads to 95% decreases in LH and FSH responses in rhesus monkeys