[Study on passive immunization for biological action of oxytocin (author's transl)].

The physiological roles of oxytocin in pregnant rats were studied by passive immunization. Oxytocin antibody (A/S OT) was produced to synthetic OT in rabbits by immunizing with OT conjugated to bovine serum albumin by glutaraldehyde method. Then the sera in the rabbits were tested for the potency of antibody to OT by double antibody radioimmunoassay. On the nineteenth day of pregnancy, each of ten rats was daily injected subcutaneously with 1 ml of A/S OT up to parturition. The mean gestation period in the treated rats was 23.1 +/- 0.31 days and in the control rats (normal rabbit serum: NRS treated), 23.2 +/- 0.13 days. The amount, 1 ml of antiserum, was inferred to be capable to sufficiently neutralize the endogenous oxytocin in pregnant rats. This antiserum was proved to inhibit the biological action of OT by Magnus equipment. These data suggest that, the hypothesis that OT may play a primary role of initiation of labor, is necessary to be reevaluated.