SERUM PROLACTIN AND LH IN CHRONICALLY-CANNULATED CYCLING RATS AFTER INTRA-ATRIAL ADMINISTRATION OF OXYTOCIN

Abstract

Chronically-cannulated female rats that were adapted to frequent handling were used for a kinetic study where oxytocin was injected into an indwelling atrial cannula and blood sampled every 5-10 min for 2 h after the injection. The plasma was assayed for prolactin and LH [luteinizing hormone] by radioimmunoassay, to ascertain whether in cycling rats oxytocin exerts any effect on the circulating level of either hormone. The advantage of this experimental model is that each animal served as a control for itself, and that only minor stress was recorded during the experiments. Oxytocin does not alter circulating LH levels, and complement previous reports on the lack of effect of oxytocin on serum prolactin in the cycling rat.