Plasticity of central mechanisms for cough.
Cough is associated with plasticity of putative cough afferent fibres, but whether plasticity in the brainstem network contributes is less well understood. A key site in the CNS network is the nucleus tractus solitarius (NTS), the first synaptic contact of the primary afferent fibres. We sought to develop a conscious guinea pig model to detect enhanced cough, to focus on the NTS as a potential site for plasticity, and to test a role for substance P in the NTS since the neuropeptide has been implicated in plasticity of the vagal afferent fibres. Guinea pigs were exposed to second-hand tobacco smoke (SHS) or filtered air (FA) from 1-6 weeks of age. At 5 weeks, cannulae were implanted in the NTS. At 6 weeks, either vehicle or a neurokinin 1 (NK-1) receptor antagonist was injected into the NTS of the conscious guinea pigs who were then exposed to citric acid aerosol. SHS exposure significantly enhanced citric acid-induced cough (56%, P<0.05), an effect attenuated by NTS NK-1 receptor blockade (P<0.05). The findings suggest that one possible mechanism for plasticity in cough is related to substance P effects in the NTS. Future studies will be required to investigate the possible mechanisms underlying the role of substance P as well as other mechanisms in generating SHS-induced cough.
Bonham
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AC
Department of Pharmacology, University of California Davis, Tupper Hall Room 1310, One Shields Avenue, Davis, CA 95616-0635, USA.
Sekizawa
S-i
SI
Joad
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JP
D000818:Animals; D002490:Central Nervous System / Q000502:physiology*; D003371:Cough / Q000503:physiopathology*; D006168:Guinea Pigs; D006801:Humans; D023421:Models, Animal; D009473:Neuronal Plasticity; D012018:Reflex; D017552:Solitary Nucleus / Q000502:physiology; D013373:Substance P / Q000494:pharmacology*
D013373:Substance P