Perinatal nicotine exposure impairs the maturation of glutamatergic inputs in the auditory brainstem

• Published in: The Journal of physiology Vol. 595; no. 11; pp. 3573 - 3590
• Main Authors: Baumann, Veronika J., Koch, Ursula
• Format: Journal Article
• Language: English
• Published: England Wiley Subscription Services, Inc 01-06-2017; John Wiley and Sons Inc
• Subjects: Acetylcholine; Acetylcholine receptors (nicotinic); Acoustics; Advertising accounts; Animal models; Animals; auditory brainstem; Brain stem; Brain Stem - drug effects; Brain Stem - embryology; Children; Cochlea; Cochlear nuclei; Down-Regulation; Excitatory Postsynaptic Potentials; excitatory synaptic transmission; Exposure; Female; Firing pattern; Glutamatergic transmission; Glutamic Acid - metabolism; Granule cells; Information processing; Lemniscus (lateral); Male; Maturation; Mice; Mice, Inbred C57BL; Neurogenesis; Neurons; Neurons - cytology; Neurons - drug effects; Neurons - metabolism; Neuroscience ‐ development/plasticity/repair; Nicotine; Nicotine - adverse effects; Nicotinic Agonists - adverse effects; nicotinic receptor; Nuclei (cytology); Perinatal exposure; Pregnancy; Prenatal Exposure Delayed Effects - metabolism; Prenatal Exposure Delayed Effects - pathology; Prenatal Exposure Delayed Effects - physiopathology; Receptors, Cholinergic - genetics; Receptors, Cholinergic - metabolism; Research Paper; SIDS; Smoking; Speech; Speech sounds; Stimulation; Sudden infant death syndrome; Synapses - drug effects; Synapses - metabolism; excitatory synaptic transmission; nicotinic receptor; auditory brainstem
• ISSN: 0022-3751; 1469-7793
• DOI: 10.1113/JP274059

Key points
Chronic perinatal nicotine exposure causes abnormal auditory brainstem responses and auditory processing deficits in children and animal models.
The effect of perinatal nicotine exposure on synaptic maturation in the auditory brainstem was investigated in granule cells in the ventral nucleus of the lateral lemniscus, which receive a single calyx‐like input from the cochlear nucleus.
Perinatal nicotine exposure caused a massive reduction in the amplitude of the excitatory input current.
This caused a profound decrease in the number and temporal precision of spikes in these neurons.
Perinatal nicotine exposure delayed the developmental downregulation of functional nicotinic acetylcholine receptors on these neurons.
Maternal smoking causes chronic nicotine exposure during early development and results in auditory processing deficits including delayed speech development and learning difficulties. Using a mouse model of chronic, perinatal nicotine exposure we explored to what extent synaptic inputs to granule cells in the ventral nucleus of the lateral lemniscus are affected by developmental nicotine treatment. These neurons receive one large calyx‐like input from octopus cells in the cochlear nucleus and play a role in sound pattern analysis, including speech sounds. In addition, they exhibit high levels of α7 nicotinic acetylcholine receptors, especially during early development. Our whole‐cell patch‐clamp experiments show that perinatal nicotine exposure causes a profound reduction in synaptic input amplitude. In contrast, the number of inputs innervating each neuron and synaptic release properties of this calyx‐like synapse remained unaltered. Spike number and spiking precision in response to synaptic stimulation were greatly diminished, especially for later stimuli during a stimulus train. Moreover, chronic nicotine exposure delayed the developmental downregulation of functional nicotinic acetylcholine receptors on these neurons, indicating a direct action of nicotine in this brain area. This presumably direct effect of perinatal nicotine exposure on synaptic maturation in the auditory brainstem might be one of the underlying causes for auditory processing difficulties in children of heavy smoking mothers.
Key points
Chronic perinatal nicotine exposure causes abnormal auditory brainstem responses and auditory processing deficits in children and animal models.
The effect of perinatal nicotine exposure on synaptic maturation in the auditory brainstem was investigated in granule cells in the ventral nucleus of the lateral lemniscus, which receive a single calyx‐like input from the cochlear nucleus.
Perinatal nicotine exposure caused a massive reduction in the amplitude of the excitatory input current.
This caused a profound decrease in the number and temporal precision of spikes in these neurons.
Perinatal nicotine exposure delayed the developmental downregulation of functional nicotinic acetylcholine receptors on these neurons.