Localization of neuronal nitric oxide synthase-immunoreactivity within sub-populations of noradrenergic A1 and A2 neurons in the rat.
The noradrenergic cells of the ventrolateral medulla (VLM) and the nucleus tractus solitarii (NTS) are implicated in the control of a variety of cardiovascular, respiratory and neuroendocrine functions. The present study has used antibodies raised against rat neuronal nitric oxide synthase (nNOS) and tyrosine hydroxylase (TH) to determine whether nNOS is expressed by A1 and A2 noradrenergic neurons. Double-labelling immunofluorescence experiments revealed that approximately 10% of TH-immunoreactive cells in the rostral NTS and 6% in the caudal NTS, were immunoreactive for nNOS. In the rostral VLM, only 1% of cells were double-labelled while approximately 9% of the TH-immunoreactive cells in the caudal VLM were immunoreactive for nNOS. These findings indicate that sub-populations of the A1 and A2 noradrenergic neurons are capable of generating nitric oxide and suggest a direct role for this neuronal messenger in the regulation of noradrenergic activity within the brain.
Simonian
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Department of Neurobiology, Babraham Institute, Cambridge, UK.
Herbison
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D000818:Animals; D005455:Fluorescent Antibody Technique; D007150:Immunohistochemistry; D008526:Medulla Oblongata / Q000166:cytology / Q000502:physiology*; D009474:Neurons / Q000166:cytology* / Q000201:enzymology / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000032:analysis*; D051381:Rats; D017208:Rats, Wistar; D018340:Receptors, Adrenergic, alpha-1 / Q000502:physiology*; D018341:Receptors, Adrenergic, alpha-2 / Q000502:physiology*; D017552:Solitary Nucleus / Q000166:cytology / Q000502:physiology*; D014446:Tyrosine 3-Monooxygenase / Q000032:analysis
D018340:Receptors, Adrenergic, alpha-1; D018341:Receptors, Adrenergic, alpha-2; D019001:Nitric Oxide Synthase; D014446:Tyrosine 3-Monooxygenase