Immunocytochemical evidence for retrograde axonal transport of exogenous albumin in adult rat brain stem motor neurons.
Serum albumin is present in cranial nerve motor neurons in the brain. This is suggested to be due to uptake into peripheral axon terminals with subsequent retrograde axonal transport to the perikarya of the motor nuclei. Indirect evidence for uptake and retrograde axonal transport of albumin in a cranial nerve has been presented previously e.g. by demonstration of fluorescence of the albumin-bound dye Evans blue in the neurons of the hypoglossal nucleus subsequent to injection in the tongue. In this study we present direct evidence for retrograde axonal transport of albumin. Human albumin was injected into the tongue of adult rats, and immunocytochemically detected with an antibody, which selectively reacted with human albumin. In brains processed 24 hours or later after injection, a positive reaction was seen in the neurons of the hypoglossal nucleus. The immunoreaction product was localized as perinuclear granules in an otherwise unstained perikaryon probably associated with the endosomal-lysosomal system. Thus, albumin present in hypoglossal motor neurons appears to originate from uptake in peripheral axon terminals. Judging from the early appearance after injection, this transport probably occurs by a fast component of retrograde axonal transport.
Moos
T
T
Department of Medical Anatomy A, Panum Institute, University of Copenhagen, Denmark.
Stagaard
M
M
Møllgård
K
K
D000818:Animals; D001369:Axons / Q000378:metabolism*; D001692:Biological Transport; D001933:Brain Stem / Q000166:cytology / Q000378:metabolism* / Q000502:physiology; D005070:Evans Blue; D007002:Hypoglossal Nerve / Q000502:physiology; D007150:Immunohistochemistry; D007267:Injections; D008297:Male; D009046:Motor Neurons / Q000378:metabolism*; D051381:Rats; D012709:Serum Albumin / Q000493:pharmacokinetics*; D014059:Tongue
D012709:Serum Albumin; D005070:Evans Blue