Bulbospinal neuropeptide Y-immunoreactive neurons in the rat: comparison with adrenaline-synthesising neurons.
Immunohistochemistry and retrograde tracing using cholera toxin B subunit colloidal gold (CTB-gold) has been used to identify neurons in the medulla that contain neuropeptide Y and project to the area of the intermediolateral cell column in either the upper (T2-T4) or the lower (T8-T9) thoracic spinal cord. The rostrocaudal distributions of neuropeptide Y neurons and neuropeptide Y/CTB-gold neurons have been compared with the distributions of adrenaline-synthesising, phenylethanolamine N-methyltransferase-containing neurons and phenylethanolamine N-methyltransferase/CTB-gold neurons visualised in adjacent sections. In particular areas of the rostral medulla similarities in the numbers and distributions of neuropeptide Y neurons and phenylethanolamine N-methyltransferase neurons suggested a coexistence of the peptide within the catecholamine neurons. However, at the most rostral levels of the rostral ventral medulla, the large numbers of phenylethanolamine N-methyltransferase neurons were not matched by similar numbers of neuropeptide Y neurons, so that the phenylethanolamine N-methyltransferase neurons in this area could not all contain neuropeptide Y. In the rostral ventral medulla fewer neuropeptide Y/CTB-gold neurons than phenylethanolamine N-methyltransferase/CTB-gold neurons were observed, so that these bulbospinal peptide neurons might define a subset of the phenylethanolamine N-methyltransferase/CTB-gold neurons, accounting for 25% of the total phenylethanolamine N-methyltransferase bulbospinal projection from the rostral ventral medulla. Other neuropeptide Y/CTB-gold neurons in the dorsal medulla are also likely to contain phenylethanolamine N-methyltransferase. Finally, a population of neuropeptide Y/CTB-gold neurons was identified in the caudal ventral medulla, these neurons appear not to contain catecholamine synthesising enzymes.
Minson
J B
JB
Department of Medicine, School of Medicine, Flinders University of South Australia, Bedford Park.
Llewellyn-Smith
I J
IJ
Pilowsky
P M
PM
Chalmers
J P
JP
D000818:Animals; D001370:Axonal Transport; D015415:Biomarkers / Q000032:analysis; D001794:Blood Pressure / Q000502:physiology; D001931:Brain Mapping; D002772:Cholera Toxin / Q000493:pharmacokinetics; D004525:Efferent Pathways / Q000737:chemistry / Q000648:ultrastructure; D004837:Epinephrine / Q000096:biosynthesis*; D017979:Gold Colloid; D008297:Male; D008526:Medulla Oblongata / Q000737:chemistry / Q000166:cytology* / Q000502:physiology; D009419:Nerve Tissue Proteins / Q000032:analysis; D009474:Neurons / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D009478:Neuropeptide Y / Q000032:analysis*; D010625:Phenylethanolamine N-Methyltransferase / Q000032:analysis; D051381:Rats; D011921:Rats, Inbred WKY; D013116:Spinal Cord / Q000737:chemistry / Q000166:cytology*
D015415:Biomarkers; D017979:Gold Colloid; D009419:Nerve Tissue Proteins; D009478:Neuropeptide Y; D002772:Cholera Toxin; D010625:Phenylethanolamine N-Methyltransferase; D004837:Epinephrine