Premium
Cellular localization of spinal A 2A receptors giving rise to phrenic motor facilitation in rats
Author(s) -
Seven Yasin Baris,
Perim Raphael R,
Hobson Orinda R,
Simon Alec,
Mitchell Gordon S
Publication year - 2017
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.31.1_supplement.1053.12
Subject(s) - phrenic nerve , receptor , motor neuron , agonist , medicine , neuroscience , anesthesia , biology , spinal cord , chemistry , respiratory system
Cervical spinal adenosine 2A (A 2A ) receptor activation elicits plasticity in the phrenic motor system. For example, spinal A 2A receptor‐dependent phrenic motor facilitation (pMF) is observed following severe acute intermittent hypoxia (Nichols et al., 2012), and can be elicited by intrathecal A 2A receptor agonist administration (Golder et al., 2008). Since the specific cells expressing the relevant A 2A receptors for this form of phrenic motor plasticity are not known, we tested the hypothesis that the relevant A 2A receptors are expressed in phrenic motor neurons per se. To test this hypothesis, we combined neurophysiology, neuropharmacology, immunofluorescence and RNA interference. Intrapleural injections of cholera toxin B subunit (CtB) were used to label phrenic motor neurons. Intrapleural injections of siRNAs (3 consecutive days) targeting A 2A receptor mRNA (siA2A), or non‐targeting siRNAs (siNT) were used to knock‐down A 2A expression within phrenic motor neurons. Successful knock‐down of A 2A receptors was confirmed by ~45% decrease in A 2A receptor immunolabeling within CtB identified phrenic motor neurons (p<0.05). Minimal A 2A receptor expression could be detected in adjacent astrocytes or microglia; further, there was no evidence for knockdown in C4 interneurons or non‐phrenic motor neurons. Selective phrenic motor neuron knock‐down using this method was similar to prior reports using siRNAs targeting either TrkB or PKCθ. In anesthetized, paralyzed and ventilated rats, pMF induced by intrathecal injections of the A 2A receptor agonist CGS21680 was significantly attenuated in the siA2A (37%) versus the siNT group (147%; p<0.05). There were no significant effects of siA2A on phrenic burst frequency. Our results support the hypothesis that the A 2A receptors giving rise to A 2A receptor‐induced PMF are expressed within phrenic motor neurons versus glia, non‐phrenic motor neurons or segmental interneurons. Support or Funding Information Supported by NIH HL69064 and the McKnight Brain Institute.