title: Chronic social defeat up-regulates expression of norepinephrine transporter in rat brains.
abstract: Stress has been reported to activate the locus coeruleus (LC)-noradrenergic system. However, the molecular link between chronic stress and noradrenergic neurons remains to be elucidated. In the present study adult Fischer 344 rats were subjected to a regimen of chronic social defeat (CSD) for 4weeks. Measurements by in situ hybridization and Western blotting showed that CSD significantly increased mRNA and protein levels of the norepinephrine transporter (NET) in the LC region and NET protein levels in the hippocampus, frontal cortex and amygdala. CSD-induced increases in NET expression were abolished by adrenalectomy or treatment with corticosteroid receptor antagonists, suggesting the involvement of corticosterone and corticosteroid receptors in this upregulation. Furthermore, protein levels of protein kinase A (PKA), protein kinase C (PKC), and phosphorylated cAMP-response element binding (pCREB) protein were significantly reduced in the LC and its terminal regions by the CSD paradigm. Similarly, these reduced protein levels caused by CSD were prevented by adrenalectomy. However, effects of corticosteroid receptor antagonists on CSD-induced down-regulation of PKA, PKC, and pCREB proteins were not consistent. While mifeprestone and spironolactone, either alone or in combination, totally abrogate CSD effects on these protein levels of PKA, PKC and pCREB in the LC and those in the hippocampus, frontal cortex and amygdala, their effects on PKA and PKC in the hippocampus, frontal cortex and amygdala were region-dependent. The present findings indicate a correlation between chronic stress and activation of the noradrenergic system. This correlation and CSD-induced alteration in signal transduction molecules may account for their critical effects on the development of symptoms of major depression.
authors: Department of Pharmacology, Quillen College of Medicine, East Tennessee State University, Johnson City, TN 37614, USA.
authors: Ping
authors: P
authors: Chen
authors: Yan
authors: Y
authors: Fan
authors: Ying
authors: Y
authors: Li
authors: Zhongwen
authors: Z
authors: Sun
authors: Garth
authors: G
authors: Bissette
authors: Meng-Yang
authors: MY
authors: Zhu
mesh_terms: D000315:Adrenalectomy; D000818:Animals; D001921:Brain / Q000378:metabolism*; D003345:Corticosterone / Q000378:metabolism; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004195:Disease Models, Animal; D015536:Down-Regulation; D006624:Hippocampus / Q000378:metabolism; D008297:Male; D009638:Norepinephrine / Q000378:metabolism*; D050484:Norepinephrine Plasma Membrane Transport Proteins / Q000378:metabolism*; D011493:Protein Kinase C / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011916:Rats, Inbred F344; D020318:Rats, Long-Evans; D015398:Signal Transduction / Q000187:drug effects* / Q000502:physiology; D013315:Stress, Psychological; D015854:Up-Regulation
chemical_list: D017362:Cyclic AMP Response Element-Binding Protein; D050484:Norepinephrine Plasma Membrane Transport Proteins; D012333:RNA, Messenger; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; D003345:Corticosterone; D009638:Norepinephrine