Effects of chronic nicotinic excitation on central glutamatergic control of breat

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DESCRIPTION (provided by applicant): Nicotine is a neuroteratogen that crosses the blood brain barrier, binds to neuronal nicotinic acetylcholine receptors (nAChRs), and alters brain development in human and non-human animals. In central respiratory neurons, there is evidence that in utero exposure to nicotine increases both fast excitatory and inhibitory neurotransmission, but the anatomical and functional details of this neuroplasticity are unclear. These data seem paradoxical, but there is growing evidence that many types of central neurons and neural networks respond to inappropriate synaptic input (e.g. nicotine) by adjusting their excitability to achieve the appropriate balance of inhibitory and excitatory neurotransmission. Consequently, the present proposal aims to investigate mechanisms of neural plasticity in central respiratory control regions that regulate breathing pattern resulting from chronic nicotine exposure during development. The hypothesis guiding this proposal is that prenatal nicotine exposure (PNE) leads to an increase in glutamatergic fast excitatory neurotransmission in medullary respiratory regions that generate respiratory rhythm and control the frequency and amplitude of motor output. We will use a "split-bath" brainstem spinal cord preparation with and without pressure microinjections of glutamate receptors agonists and antagonists (Specific aim 1), as well as whole-cell patch clamp electrophysiology to examine synaptic changes that may be induced by PNE (Specific aim 2). We suggest that the PNE-induced increase in excitatory neurotransmission may be a critical link between the persistent excitation of nAChRs and in vivo respiratory control abnormalities, especially when faced with respiratory challenges. PUBLIC HEALTH RELEVANCE: Studying isolated neural networks that control central breathing behavior is fundamental to understanding the more integrated mammalian respiratory system, as well as pathophysiological conditions that effect human respiratory control during prenatal and postnatal development. Here we use two distinct and highly tractable in vitro models that are similar to in vivo breathing behavior to investigate how medullary respiratory networks are altered by prenatal nicotine exposure. This knowledge is key in understanding the numerous links between the in utero exposure to nicotine (i.e., cigarette smoking) and life threatening conditions in which breathing regulation is altered.