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Neuronal Responses in Raphe Nucleus of Medulla Oblongata to Electroacupuncture: relation to opioids and serotonin
Author(s) -
Guo Zhiling,
Moazzami Ali R.,
TjenALooi Stephanie,
Longhurst John C.
Publication year - 2007
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.21.5.a472-b
Subject(s) - nucleus raphe magnus , medulla oblongata , electroacupuncture , serotonergic cell groups , raphe nuclei , raphe , dorsal raphe nucleus , serotonin , chemistry , medicine , endocrinology , anesthesia , central nervous system , acupuncture , serotonergic , receptor , pathology , alternative medicine
The midline medulla oblongata includes the nucleus raphe obscurus (NRO), nucleus raphe magnus (NRM) and raphe pallidus (NRP), and is involved in regulation of cardiovascular responses. Opioids and serotonin (5‐HT) function as important neurotransmitters in this region. We previously demonstrated that electroacupuncture (EA) at the Neiguan‐Jianshi acupoints (P5–P6, overlying the median nerves) attenuates sympathoexcitatory blood pressure reflexes through an influence on several brain regions. However, the role of these three raphe nuclei in the acupuncture responses is unknown. In the present study, we evaluated activation of the raphe nuclei induced by EA by detecting c‐Fos, an immediate early gene, and observing its relationship with neurons containing opioids and/or 5‐HT. To enhance detection of perikarya containing opioid peptides, colchicine (90–100 μg/kg) was administered in the subarachnoid space in anesthetized cats 28–30 hours before sham‐operated control for EA or EA, which was performed at P5–P6 acupoints for 30 min. Perikarya containing enkephalin and/or 5‐HT, but not β‐endorphin, were found in the raphe nucleus. Compared to controls (n=5), c‐Fos immunoreactivity and neurons double‐labeled with c‐Fos and either enkephalin or 5‐HT were frequently found in NRO, NRM and NRP, especially in NRP (n=6, all P<0.05) in EA‐treated cats. Moreover, neurons triple‐labeled with c‐Fos, enkephalin and 5‐HT were noted often in the NRP following EA stimulation. These results suggest that the medullary raphe nuclei, particularly the NRP, may process somatic signals during EA and through an opioid or serotoninergic mechanism participate in EA‐modulation of cardiovascular function (supported by NIH, HL‐72125 and HL‐63313).