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DIFFERENTIATION OF DOPAMINERGIC AND NORADRENERGIC NEURONS IN RAT SPINAL CORD
Author(s) -
Commissiong John W.,
Galli Corrado L.,
Neff Norton H.
Publication year - 1978
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1978.tb12403.x
Subject(s) - spinal cord , locus coeruleus , endocrinology , chemistry , medicine , dopaminergic , reserpine , norepinephrine , cord , dopamine , cerebellum , anesthesia , central nervous system , neuroscience , biology , surgery
— Norepinephrine (NE), dopamine (DM) and 3‐methoxy‐4‐hydroxyphenylacetic acid (HVA) content have been measured in different parts of rat spinal cord and cerebellum by a gas chromatographic mass spectrometric method. In cerebellum, which does not contain dopaminergic neurons, the ratio of NE to DA content was 47, whereas in parts of the spinal cord this ratio varied between 11 and 19. In the cord after desipramine (25 mg/kg, i.p.) plus 6‐hydroxydopamine (6‐HDA, 100/jg intracisternally), there was a significant depletion of DM but not of NE. Conversely, after benztropine (25 mg/kg, i.p.) plus 6‐HDA there was a significant depletion of NE but not of DM. Chlorpromazine (10 mg/kg, i.p.) or clozapine (25 mg/kg, i.p.) caused a significant increase in spinal cord HVA concentration 1 h after treatment. Evidence is presented which suggests that the increased HVA measured in the cord did not originate in the brain. After electrolytic lesion of the locus coeruleus there was a significant reduction of NE but not of DM. Spinal cord DM and NE were depleted by reserpine in a dose‐dependent manner, the threshold dose for DM depletion being less than that for NE depletion. Seven days after cord transection at T 10 spinal cord DM was significantly reduced in the lumbar region. These results suggest that dopaminergic neurons exist in rat spinal cord independently of noradrenergic neurons and that the DM is likely to be present in the terminals of descending axons.