Ultrastructural localization of beta-arrestin-1 and -2 in rat lumbar spinal cord.
beta-arrestins play significant roles in agonist-mediated desensitization of G protein-coupled receptors. Although the presence of beta-arrestin subtypes, beta-arrestin-1 and(- 2) in rat brain has been studied extensively, their existence in the spinal cord has not been described. In the current study, we performed immunohistochemical analyses of beta-arrestins at both light and electron microscopic levels using rat lumbar 1-2 spinal cord segments. Intense immunoreactivity for beta-arrestin-1 was found in the motoneurons in lamina IX of the ventral horn and elongated cells in the dorsal nucleus of Clarke. Modest immunoreactivity was detected among the neurons of laminae V and VII/VIII, and weaker immunoreactivity in laminae III, IV, and X. beta-arrestin-2 immunoreactivity was also distributed through laminae III-X in the order of IX > dorsal nucleus of Clarke > V > VII/VIII > IV > III > X. Laminae I and II did not show immunoreactivity. At the electron microscopic level, both beta-arrestin-immunoreactive and nonimmunoreactive dendrites were observed, whereas axons and terminal boutons were devoid of immunoreactivity. In immunoreactive dendrites most beta-arrestin immunoreactivity was distributed throughout the cytoplasm, demonstrating their association with microtubules. In addition, strong immunoreactivity was often found at postsynaptic densities. Our results thus suggest beta-arrestins' possible involvement in both motor and sensory mechanisms at the postsynaptic level in rat lumbar spinal cord.
Kittel
A
A
Institute of Experimental Medicine, The Hungarian Academy of Sciences, 1083 Budapest, Hungary.
Komori
N
N
D000818:Animals; D019390:Arrestins / Q000032:analysis*; D007150:Immunohistochemistry; D008161:Lumbosacral Region; D008297:Male; D016253:Microscopy, Immunoelectron; D051381:Rats; D017207:Rats, Sprague-Dawley; D013116:Spinal Cord / Q000737:chemistry*; D013569:Synapses / Q000737:chemistry; D000071559:beta-Arrestin 1; D000071560:beta-Arrestin 2; D000071557:beta-Arrestins
C000605256:Arrb1 protein, rat; C000605257:Arrb2 protein, rat; D019390:Arrestins; D000071559:beta-Arrestin 1; D000071560:beta-Arrestin 2; D000071557:beta-Arrestins