Late onset deficits in synaptic plasticity in the valproic acid rat model of autism

Area of Science:

• Neuroscience
• Developmental Biology
• Pharmacology

Background:

• Valproic acid (VPA) is a widely used medication with known teratogenic effects.
• Prenatal VPA exposure in rodents serves as a model for autism spectrum disorders, inducing neurodevelopmental abnormalities.
• Early postnatal VPA exposure alters medial prefrontal cortex (mPFC) physiology, including increased NMDA receptor (NMDAR) expression and long-term potentiation (LTP).

Purpose of the Study:

• To investigate the longitudinal effects of prenatal VPA exposure on mPFC synaptic physiology into adulthood.
• To determine if early synaptic abnormalities normalize or persist into adulthood.
• To understand the long-term consequences of VPA-induced neurodevelopmental changes.

Main Methods:

• Electrophysiological recordings in adult VPA-exposed rats and control littermates.
• Assessment of NMDAR-mediated currents and LTP in the mPFC.
• Evaluation of spontaneous activity and endocannabinoid-dependent long-term depression.

Main Results:

• Adult VPA-exposed rats exhibit significantly reduced NMDAR-mediated currents and LTP in the mPFC.
• In contrast to early life, synaptic function shifts from hyper- to hypo-function in adulthood.
• Spontaneous activity and endocannabinoid-dependent long-term depression remain unaffected.

Conclusions:

• Synaptic abnormalities induced by prenatal VPA exposure persist into adulthood, presenting a different phenotype than observed in earlier developmental stages.
• The shift to reduced synaptic function in adulthood may contribute to neurodevelopmental deficits associated with VPA exposure and autism spectrum disorders.
• These findings highlight the complex, long-lasting impact of developmental VPA exposure on brain circuitry.