抄録
We found that a perfusion of fluoxetine in the dorsomedial medulla oblongata (DMM) (includes the hypoglossal nucleus, the dorsal motor nucleus of the vagus nerve, and the solitary tract nucleus) increased the 5-HT concentration and airway resistance with an occasional increase of respiratory rate, may be due to a difference in probe sites. In the present study, the role of 5-HT at the caudal DMM in respiration was examined. The role of 5-HT2 receptors in respiration was also investigated. Male mice (C57BL/6N) were anesthetized with pentobarbital sodium i.p. to insert a microdialysis probe into the DMM and placed in a double chamber plethysmograph. After waiting over 1 hour to recover from the anesthesia and to acclimatize to the chamber, extracellular fluid was collected at 1.2 μl/min of artificial cerebrospinal fluid (aCSF). Two respiratory flow curves from the nasal and the body were recorded. A perfusion of aCSF in two groups was changed with 1x10−5M fluoxetine perfusion and a co-perfusion of 1x10−5M fluoxetine and 10−5M LY-53857, a 5-HT2 receptor antagonist, respectively. The 5-HT concentration was measured using an ECD-HPLC. Respiratory rate, tidal volume and specific airway resistance (sRaw) were measured using PowerLab. The results of the preliminary experiment suggest that the respiratory rate and sRaw were increased by a perfusion of fluoxetine in the caudal DMM, with an increase of 5-HT concentration. We discuss the relationship between the respiratory response and the probe sites in the DMM, including the role of 5-HT2 receptors in the respiratory response. [Jpn J Physiol 54 Suppl:S110 (2004)]
