PACAP is expressed in sympathoexcitatory bulbospinal C1 neurons of the brain stem and increases sympathetic nerve activity in vivo

Melissa M.J. Farnham, Qun Li, Ann K. Goodchild, Paul M. Pilowsky

    Research output: Contribution to journalArticlepeer-review

    64 Citations (Scopus)

    Abstract

    Pituitary adenylate cyclase-activating polypeptide (PACAP) is an excitatory neuropeptide present in the rat brain stem. The extent of its localization within catecholaminergic groups and bulbospinal sympathoexcitatory neurons is not established. Using immunohistochemistry and in situ hybridization, we determined the extent of any colocalization with catecholaminergic and/or bulbospinal projections from the brain stem was determined. PACAP mRNA was found in tyrosine hydroxylase-immunoreactive (TH-ir) neurons in the C1-C3 cell groups. In the rostral ventrolateral medulla (RVLM), PACAP mRNA was found in 84% of the TH-ir neurons and 82% of bulbospinal TH-ir neurons. The functional significance of these PACAP mRNA positive bulbospinal neurons was tested by intrathecal administration of PACAP-38 in anaesthetized rats. Splanchnic sympathetic nerve activity doubled (110%) and heart rate rose significantly (19%), although blood pressure was unaffected. In addition, as previously reported, PACAP was found in the A1 cell group but not in the A5 cell group or in the locus coeruleus. The RVLM is the primary site responsible for the tonic and reflex control of blood pressure through the activity of bulbospinal presympathetic neurons, the majority of which contain TH. The results indicate 1) that pontomedullary neurons containing both TH and PACAP that project to the intermediolateral cell column originate from C1-C3 and not A5, and 2) intrathecal PACAP-38 causes a prolonged, sympathoexcitatory effect.

    Original languageEnglish
    Pages (from-to)R1304-R1311
    Number of pages8
    JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
    Volume294
    Issue number4
    DOIs
    Publication statusPublished - 1 Apr 2008

    Fingerprint

    Dive into the research topics of 'PACAP is expressed in sympathoexcitatory bulbospinal C1 neurons of the brain stem and increases sympathetic nerve activity in vivo'. Together they form a unique fingerprint.

    Cite this