Prednisolone induces microglial activation in the subnucleus caudalis of the rat trigeminal sensory complex.
Prednisolone is a member of synthetic glucocorticoids which are widely used to treat chronic inflammatory diseases. In this study, neuronal degeneration and cell death, and glial reaction were investigated in the rat trigeminal ganglion (TG) and brainstem after subcutaneous injection of prednisolone for 7 days. Expression of c-Jun activating transcription factor 3 and caspase-3 was absent or infrequent in the TG, and cranial sensory and motor nuclei of saline- and prednisolone-treated animals. In these animals, distribution of calcitonin gene-related peptide-immunoreactive (-IR) neurons and nerve fibers was similar in the brainstem. In addition, the number of Iba1- and glial fibrillary acidic protein (GFAP)-IR cells with some processes in the brainstem was barely affected by prednisolone treatment. However, the treatment increased ramification of Iba1-IR processes in the subnucleus caudalis of the trigeminal sensory complex. Prednisolone scarcely influenced the morphology of GFAP-IR cells in the brainstem. Expression of p38 mitogen-activated protein kinase was very rare in the brainstem of saline- and prednisolone-treated animals. The present study suggests that microglia are activated by prednisolone in the subnucleus caudalis of the trigeminal sensory complex. The glucocorticoid may affect nociceptive transmission in the brainstem.
Yu
Y
Endo
Noriaki
N
Shoji
Yusuke
Y
Shimada
Eriko
E
Kasahara
Masahiro
M
Iikubo
Tadasu
T
Sato
Takashi
T
Sasano
Hiroyuki
H
Ichikawa
D051700:Activating Transcription Factor 3 / Q000378:metabolism; D000818:Animals; D001933:Brain Stem / Q000187:drug effects / Q000201:enzymology; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism; D003712:Dendrites / Q000187:drug effects / Q000378:metabolism; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D008297:Male; D008840:Microfilament Proteins / Q000378:metabolism; D017628:Microglia / Q000187:drug effects / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D011239:Prednisolone / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D014275:Trigeminal Caudal Nucleus / Q000187:drug effects / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
D051700:Activating Transcription Factor 3; C100745:Aif1 protein, rat; C497108:Atf3 protein, rat; D002135:Calcium-Binding Proteins; D005904:Glial Fibrillary Acidic Protein; D008840:Microfilament Proteins; D011239:Prednisolone; D048051:p38 Mitogen-Activated Protein Kinases; D053148:Caspase 3; D015740:Calcitonin Gene-Related Peptide