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Published on: May 24, 2018
The effects of postnatal phthalate exposure on the development of auditory temporal processing in rats
Bong Jik Kim1, Jungyoon Kim2, Vanhnansy Keoboutdy3
1Wide River Institute of Immunology, Seoul National University College of Medicine, Seoul, South Korea; The Environmental Health Center(Neurodevelopment), Dankook University Medical Center, Cheonan, South Korea.
Insights
Neonatal phthalate exposure may impair auditory temporal processing in rats. This study found that phthalate-exposed rats had higher gap detection thresholds, suggesting developmental disruptions in auditory function.
Area of Science:
- Neuroscience
- Developmental Biology
- Toxicology
Background:
- The central auditory pathway develops postnatally, influenced by sensory input.
- Phthalates are neurotoxic chemicals linked to attention deficits and infant neurobehavioral issues.
Purpose of the Study:
- To investigate the effects of neonatal phthalate exposure on auditory temporal processing development in rats.
Main Methods:
- Neonatal Sprague-Dawley rats were divided into phthalate and control groups.
- Phthalate exposure occurred daily from postnatal day 8 to 28.
- Auditory Brainstem Response (ABR) and Gap Prepulse Inhibition of Acoustic Startle (GPIAS) were measured at postnatal day 28.
Main Results:
- No significant differences in hearing thresholds were found between groups.
- A significant difference in GPIAS was observed at a 20 ms gap duration (p=0.037).
- The phthalate group showed a higher mean gap detection threshold (44.0 ms vs 20.0 ms), though not statistically significant (p=0.065), with a more scattered distribution.
Conclusions:
- Neonatal phthalate exposure may disrupt the development of auditory temporal processing.
- Phthalates could impact the maturation of neural pathways crucial for processing sound timing.
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.
