Phosphorylated extracellular signal-regulated kinase 1/2 immunoreactivity identifies a novel subpopulation of sympathetic preganglionic neurons.
Distinct chemical codes are thought to reflect functional specificity in sympathetic preganglionic neurons (SPN). Although a number of chemical candidates have been identified including neurotransmitter-related, calcium-binding and other proteins, signal transduction proteins have been largely neglected. Not only might these chemicals allow discrimination of functionally unique chemical signatures, but they may also identify activated neurons. Immunoreactivity (ir) to phosphorylated extracellular signal-regulated kinase 1/2 (p-ERK1/2) was differentially located within the thoracic spinal cord depending upon which of three forms of killing was used: the only exception to this was the intermediolateral cell column (IML) which was consistently, densely labeled. The presence or absence of p-ERK1/2 in SPN (n=17,541) within the IML of the thoraco-lumbar spinal cord was determined in seven rats. SPN were identified on the basis of their location, size and that they contained choline acetyltransferase ir. On average, 58% of SPN contained p-ERK1/2, however, more SPN in both the upper (72%; C8-T4) and lower (78%; T11-L3) thoraco-lumbar spinal cord contained p-ERK1/2-ir than the middle thoracic region (47%; T4-T10). p-ERK1/2-ir was also examined in SPN (n=1895) innervating the adrenal medulla (identified by retrograde tracing using cholera toxin B subunit) combined with localization of neuronal nitric oxide synthase (nNOS) in three rats. On average, 64% of adrenal SPN contain p-ERK1/2-ir, and it was confirmed that all adrenal SPN contain nNOS-ir. It appears that p-ERK1/2-ir SPN, described in this study, have tonically activated receptors that are coupled to intracellular signal transduction pathways that lead to the phosphorylation of ERK1/2.
Springell
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DA
Hypertension and Stroke Research Laboratories, Department of Physiology, Institute for Biomedical Research and School of Medical Sciences, University of Sydney, Royal North Shore Hospital, St. Leonards, NSW 2065, Australia.
Powers-Martin
K
K
Phillips
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JK
Pilowsky
P M
PM
Goodchild
A K
AK
D000818:Animals; D001339:Autonomic Fibers, Preganglionic / Q000187:drug effects / Q000378:metabolism*; D002452:Cell Count / Q000379:methods; D002772:Cholera Toxin / Q000378:metabolism; D002795:Choline O-Acetyltransferase / Q000378:metabolism; D006221:Halothane / Q000494:pharmacology; D007150:Immunohistochemistry / Q000379:methods; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D008297:Male; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009474:Neurons / Q000145:classification* / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D052248:Nitric Oxide Synthase Type I; D010424:Pentobarbital / Q000494:pharmacology; D010766:Phosphorylation; D051381:Rats; D017207:Rats, Sprague-Dawley; D013116:Spinal Cord / Q000166:cytology / Q000187:drug effects / Q000378:metabolism
D047908:Intracellular Signaling Peptides and Proteins; D009419:Nerve Tissue Proteins; D002772:Cholera Toxin; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; C496322:Nos1 protein, rat; D002795:Choline O-Acetyltransferase; D010424:Pentobarbital; D006221:Halothane