TNF alpha-p55 receptors: medullary brainstem immunocytochemical localization in normal and vagus nerve-transected rats.
Tumor necrosis factor alpha (TNF(alpha)) is a potent modulator of autonomic reflex mechanisms that control the stomach. Evidence suggests that TNF(alpha) action directly on vago-vagal reflex control circuits causes the autonomic misregulation of digestion manifested as gastrointestinal stasis, nausea, and emesis associated with illness. Neurophysiological studies indicated that TNF(alpha) may have effects on vagal afferents in the solitary nucleus, as well as neurons of the solitary nucleus (NST) and dorsal motor nucleus (DMN) of the vagus. The aim of this study was to determine the location of the TNFR1 receptor (p55) in the medulla using immunocytochemical methods. We devised a technique for localizing the p55 receptor using heat-induced antigen recovery in fixed tissue sections. This protocol allowed us to demonstrate that dense p55-immunoreactivity (p55-ir) is constitutively present on central (but not peripheral) vagal afferents in the solitary tract (ST) and nucleus; p55-ir is also present on afferents entering the spinal trigeminal nucleus. Unilateral supra-nodose vagotomy eliminated p55-ir from ipsilateral central vagal afferents. Virtually all neurons in the brainstem appeared to express p55-ir at a low level, i.e., just above background. However, vagotomy caused a dramatic up-regulation of p55-ir in vagal motor neurons. This increase in p55-ir in axotomized neurons may play a pivotal role in the connection between the occurrence of the injury and the initiation of apoptotic processes resulting in elimination of damaged neurons.
Hermann
Gerlinda E
GE
Laboratory of Autonomic Neuroscience, Pennington Biomedical Research Center, Louisiana State University, 6400 Perkins Rd., Baton Rouge, LA 70808, USA.
Hebert
Sadie L
SL
Van Meter
Montina J
MJ
Holmes
Gregory M
GM
Rogers
Richard C
RC
D000818:Animals; D015703:Antigens, CD / Q000032:analysis / Q000378:metabolism*; D001933:Brain Stem / Q000737:chemistry / Q000378:metabolism; D005260:Female; D007150:Immunohistochemistry; D008297:Male; D008526:Medulla Oblongata / Q000737:chemistry / Q000378:metabolism*; D051381:Rats; D020318:Rats, Long-Evans; D018124:Receptors, Tumor Necrosis Factor / Q000032:analysis / Q000378:metabolism*; D047888:Receptors, Tumor Necrosis Factor, Type I; D014628:Vagotomy; D014630:Vagus Nerve / Q000737:chemistry / Q000378:metabolism*
D015703:Antigens, CD; D018124:Receptors, Tumor Necrosis Factor; D047888:Receptors, Tumor Necrosis Factor, Type I