Abstract
Oxytocin plays critical roles in mammalian labor and lactation. The hormone is essential for the induction of normal labor through uterine contraction and for normal development of offspring through lactation in mammals. We recently discover a new function of oxytocin in causing plastic changes in hippocampal synapses during motherhood. Mother is "smarter". Oxytocin receptors were strongly expressed in the hippocampus of female mice. In oxytocin-perfused hippocampal slices, one-train tetanus stimulation induced long-lasting long-term potentiation (L-LTP) and phosphorylation of cyclic AMP-responsive element binding protein (CREB), and MAP kinase inhibitors blocked these inductions. An increase in CREB phosphorylation and one-train tetanus-induced L-LTP was observed in the multiparous mouse hippocampus without oxytocin application. Furthermore, intracerebroventricular injection of oxytocin in virgin mice improved long-term spatial learning in vivo, whereas an injection of oxytocin antagonist in multiparous mice significantly inhibited the improved spatial memory, L-LTP and CREB phosphorylation. In this symposium, I will review these findings and discuss the role of oxytocin in improvement of hippocampus-dependent learning and memory during motherhood. [Jpn J Physiol 54 Suppl:S62 (2004)]
