Xiang YY, Wang S, Liu M, Hirota JA, Li J, Ju W, Fan Y, Kelly MM, Ye B, Orser B, O’Byrne PM, Inman MD, Yang X, Lu WY. (2007) Nat Med. 13(7):862-7.

Abstract

γ-aminobutyric acid (GABA) is an important neurotransmitter that, through the subtype A GABA receptor (GABA_AR), induces inhibition in the adult brain. Here we show that an excitatory, rather than inhibitory, GABAergic system exists in airway epithelial cells. Both GABA_ARs and the GABA synthetic enzyme glutamic acid decarboxylase (GAD) are expressed in pulmonary epithelial cells. Activation of GABA_ARs depolarized these cells. The expression of GAD in the cytosol and GABA_ARs in the apical membranes of airway epithelial cells increased markedly when mice were sensitized and then challenged with ovalbumin, an approach for inducing allergic asthmatic reactions. Similarly, GAD and GABA_ARs in airway epithelial cells of humans with asthma increased after allergen inhalation challenge. Intranasal application of selective GABA_AR inhibitors suppressed the hyperplasia of goblet cells and the overproduction of mucus induced by ovalbumin or interleukin-13 in mice. These findings show that a previously unknown epithelial GABAergic system has an essential role in asthma.

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