Neonatal perturbation of vestibular GABAergic transmission alters spatial navigation behaviors in a rat model of dead reckoning

Abstract

Rodents navigate their surroundings using cues derived from the environment and from self-movement. To assess the role of vestibular information in providing idiothetic cues for spatial navigation, dead reckoning which requires the integration of cues on direction and distance for path-finding tasks was studied. We have reported previously that changes in GABAergic synaptic efficacy could be elicited in the vestubular nucleus during a limited time window of postnatal development. To study the role of GABAergic transmission in the developing vestibular nucleus on the acquisition of spatial recognition, we implanted above the vestibular nucleus of postnatal day 1 (P1) rats with a slice of Elvax loaded with GABAA receptor agonist (muscimol) or GABAA receptor antagonist (bicuculline). These animals were allowed to recover and were tested for dead reckoning at adult stage. When compared with the sham control group, rats treated with muscimol at P1 had a shortening of both the training days and searching time in light probe, dark probe and new location probe. On the other hand, treatment of bicuculline at P1 significantly prolonged the searching time in dark probe and new location probe. Besides, treatment of either muscimol or bicuculline had no evident effect on homeward time. Taken together, our data suggest that neonatal perturbation of GABAergic transmission in the vestibular nucleus impacted on the expression of vestibular-related spatial navigation behaviors.