Cortisol facilitates ovine fetal/maternal water transfer

Area of Science:

• Reproductive Physiology
• Perinatal Medicine
• Endocrinology

Background:

• Maternal osmotic challenges can impact fetal fluid balance.
• Arginine vasotocin (AVT) is a key hormone in fluid regulation.
• The role of AVT and cortisol in fetal-maternal water transfer is not fully understood.

Purpose of the Study:

• To investigate the effects of fetal arginine vasotocin (AVT) and cortisol on fetal plasma osmolality.
• To determine how AVT and cortisol influence fetal-maternal water transfer in response to maternal osmotic stimulation.
• To compare the effects of AVT alone versus AVT with cortisol on fetal osmolality.

Main Methods:

• Chronic catheterization of fetal lambs (129-140 days' gestation).
• Maternal infusion of 20% mannitol to induce osmotic stress.
• Fetal infusion of AVT alone or AVT with cortisol.
• Measurement of fetal plasma osmolality and comparison between study groups.

Main Results:

• Maternal mannitol infusion increased fetal plasma osmolality.
• Fetal AVT infusion significantly reduced the osmolality increase from maternal mannitol.
• Concurrent fetal infusion of AVT and cortisol enhanced the osmolality increment compared to AVT alone.
• The response with AVT and cortisol was similar to the baseline mannitol response.

Conclusions:

• Fetal AVT inhibits fetal-to-maternal water transfer following maternal osmotic stimulation.
• Cortisol, when co-infused with AVT, counteracts the inhibitory effect of AVT on fetal-maternal water transfer.
• These findings highlight a complex interplay between AVT and cortisol in regulating fetal-maternal fluid dynamics.