Maternal Oxytocin Protects Fetal Brain During Labor
Hormone has impact on fetal neurons, switching GABA function from excitatory to inhibitory
FRIDAY, Dec. 15 (HealthDay News) -- Maternal oxytocin may protect fetal neurons before delivery by increasing their resistance to trauma, according to the results of an animal study published in the Dec. 15 issue of Science. Oxytocin causes a transient drop in intracellular chloride concentration in the fetal rat brain and switches GABA action from excitatory to inhibitory, which may protect against low-oxygen conditions.
Roman Tyzio, of the Institut de Neurobiologie de la Mediterranee in Marseille, France, and associates evaluated endogenous oxytocin's effect on γ-aminobutyric acid (GABA) in the fetal brain and dosed pregnant rats with a selective oxytocin receptor antagonist. At birth, they measured the outcomes and compared the results between treated pups to age-matched controls.
Cell-attached recordings of the fetal and neonatal rat hippocampus showed sharp differences between the groups. Before birth, there was a period of time when the proportion of cells excited by GABA were in decline, with the effect peaking one to two hours before delivery, and there was a 43 percent drop in chloride concentration. Oxytocin receptor blockade prevented the drop and made the fetal brain more susceptible to anoxia-aglycemia.
"Our results suggest that oxytocin, in addition to its well-established role in labor and lactation and its multiple effects in the adult central nervous system, also exerts a powerful action on fetal neurons," the authors conclude. "This mechanism adds a previously unknown facet to the plasticity of GABA signaling via modulation of intracellular chloride concentration. The dual action produced by a single messenger in the mother and fetus enables a perfect timing for adaptation of fetal neurons to delivery."