The effects of postnatal phthalate exposure on the development of auditory temporal processing in rats.

OBJECTIVE: The central auditory pathway is known to continue its development during the postnatal critical periods and is shaped by experience and sensory inputs. Phthalate, a known neurotoxic material, has been reported to be associated with attention deficits in children, impacting many infant neurobehaviors. The objective of this study was to investigate the potential effects of neonatal phthalate exposure on the development of auditory temporal processing.

METHODS: Neonatal Sprague-Dawley rats were randomly assigned into two groups: The phthalate group (n = 6), and the control group (n = 6). Phthalate was given once per day from postnatal day 8 (P8) to P28. Upon completion, at P28, the Auditory Brainstem Response (ABR) and Gap Prepulse Inhibition of Acoustic Startle response (GPIAS) at each gap duration (2, 5, 10, 20, 50 and 80 ms) were measured, and gap detection threshold (GDT) was calculated. These outcomes were compared between the two groups.

RESULTS: Hearing thresholds by ABR showed no significant differences at all frequencies between the two groups. Regarding GPIAS, no significant difference was observed, except at a gap duration of 20 ms (p = 0.037). The mean GDT of the phthalate group (44.0 ms) was higher than that of the control group (20.0 ms), but without statistical significance (p = 0.065). Moreover, the phthalate group tended to demonstrate more of a scattered distribution in the GDT group than the in the control group.

CONCLUSION: Neonatal phthalate exposure may disrupt the development of auditory temporal processing in rats.