Neuronal metabolism and DOPA decarboxylase immunoreactivity in terminal noradrenergic sympathetic axons of rat.
This study was undertaken to determine whether immuno-histochemical staining for DOPA decarboxylase (DDC) is present in axons of rat noradrenergic sympathetic neurons. A sparse plexus of varicose axons exhibiting DDC-like immunoreactivity (DDC-IR) was associated with blood vessels and acini in the submandibular gland, but this was much less extensive than the population that exhibited tyrosine hydroxylase-like immunoreactivity (TH-IR). The varicose terminal TH-IR axons in atrium, spleen, and vas deferens were devoid of DDC-IR both in grown rats and during the post-natal period of axon growth, although weak DDC-IR was seen in large pre-terminal nerve bundles. Similar patterns of staining were seen with paraffin-embedded and with frozen, formaldehyde-fixed material. No enhancement of DDC-IR was seen in any tissue after chronic alteration of catecholamine turnover with reserpine or alpha-methyl-para-tyrosine, and the numbers of submandibular DDC-IR axons were not increased by disruption of axonal transport with colchicine or by decentralization of the superior cervical ganglion. We conclude that terminal noradrenergic axons contain insufficient DDC-IR for microscopic visualization, regardless of their metabolic state, reinforcing previous evidence that DDC-IR can be used as a histochemical marker for dopaminergic axons. By this criterion, the rat submandibular gland may receive a sparse dopaminergic innervation.
Mann
R
R
Department of Physiology, University of Melbourne, Australia.
Bell
C
C
D000818:Animals; D001369:Axons / Q000201:enzymology / Q000276:immunology / Q000378:metabolism* / Q000648:ultrastructure; D004296:Dopa Decarboxylase / Q000276:immunology*; D006321:Heart / Q000294:innervation; D007150:Immunohistochemistry / Q000379:methods; D008297:Male; D008854:Microscopy, Electron; D009474:Neurons / Q000201:enzymology / Q000378:metabolism* / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains; D013154:Spleen / Q000294:innervation; D013363:Submandibular Gland / Q000294:innervation; D013564:Sympathetic Nervous System / Q000166:cytology / Q000201:enzymology / Q000276:immunology / Q000378:metabolism*; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism; D014649:Vas Deferens / Q000294:innervation
D014446:Tyrosine 3-Monooxygenase; D004296:Dopa Decarboxylase