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Stimulatory Effect of 5‐hydroxytryptamine (5‐HT) on Rat Capsaicin‐sensitive Vagal Pulmonary Sensory Neurons via Activation of 5‐HT 3 Receptors
Author(s) -
Lin You Shuei,
Gu Qihai,
Yang Wenbin,
Lee LuYuan
Publication year - 2011
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.25.1_supplement.1077.17
Subject(s) - capsaicin , 5 ht receptor , serotonin , tropisetron , 5 ht3 receptor , chemistry , endocrinology , receptor , medicine , nodose ganglion , vagus nerve , pharmacology , stimulation
We have previously reported that 5‐HT exerted a stimulatory effect on pulmonary vagal C‐fiber afferents in anesthetized, artificially ventilated SD rats. However, whether this stimulatory effect of 5‐HT is caused by a direct action on these afferents remains unknown. In the present study, the effect of 5‐HT on the change in intracellular calcium concentration was determined in isolated nodose and jugular ganglion neurons innervating the rat lungs. Our results showed that: 1) 5‐HT induced intensive calcium transients in the vagal pulmonary neurons in a dose‐dependent manner. The highest concentration (3 μM) of 5‐HT activated 66.7% (18/27) of the capsaicin‐sensitive pulmonary neurons. 2) The 5‐HT‐indcued response was totally abolished by pretreatment of tropisetron (1 nM), a selective antagonist of 5‐HT 3 receptors. 3) Our whole‐cell perforated patch‐clamp recording showed that 5‐HT triggered an inward current in the capsaicin‐sensitive pulmonary neurons, and the response was abolished after pretreatment with tropisetron. In conclusion, 5‐HT activated pulmonary C fibers in vivo and isolated pulmonary capsaicin‐sensitive neurons in vitro, and probably resulted from its direct action on 5‐HT 3 receptors expressed in these neurons. (NIH HL 96914, fellowship NSC99‐2918‐I‐038‐001)