Maternal Dexamethasone Exposure Inhibits the Gonadotropin-Releasing Hormone Neuronal Movement in the Preoptic Area of Rat Offspring

Abstract

Migration and final positioning of gonadotropin-releasing hormone (GnRH) neurons in the preoptic area (POA) is critical for reproduction. It is known that maternal dexamethasone (DEX) exposure impairs reproductive function and behaviour in the offspring. However, it is still not known whether maternal DEX exposure affects the postnatal GnRH neurons in the offspring. This study determined the neuronal movement of enhanced green fluorescent protein (EGFP)-tagged GnRH neurons in slice culture of postnatal day 0 (P0), P5 and P50-60 transgenic male rats. Effect of maternal DEX treatment on EGFP-GnRH neuronal movement and F-actin distribution on GnRH neurons at P0 stage were studied. Time-lapse analysis of P0 and P5 EGFP-GnRH neurons displayed active cellular movement within the POA compared to young adult P50-60 stages, suggesting possible fine-tuning movement for positioning of early postnatal GnRH neurons. The DEX-treated EGFP-GnRH neurons demonstrated decreased motility in the POA and reduced F-actin distribution in the GnRH neurons at 60 h culture compared to the vehicle-treated. These results suggest that the P0 GnRH neuronal movement in the POA is altered by maternal DEX exposure, which possibly disrupts the fine-tuning process for positioning and development of early postnatal GnRH neurons in the brain, potentially linked to reproductive dysfunction in adulthood.

Kisspeptin Activates Ankrd 26 Gene Expression in Migrating Embryonic GnRH Neurons

“…Time-lapse image analysis of rat embryonic E14–GnRH neurons between the nasal and brain compartments showed movement of GnRH neurons at a velocity of 9–13 μm/h in brain slice cultures similar to E13 GnRH neurons in embryonic mouse nasal explants culture migrating at a velocity of 12–13 μm/h ( 38 ). On the other hand, our recent time-lapse imaging study of rat GnRH neurons on postnatal day 0 and day 5 showed movement of GnRH neurons at a velocity of 3–5 μm/h ( 39 ). This suggests that rat embryonic GnRH neurons have high motility and, therefore, may be a good model to determine intracellular signaling for cellular movement.…”