title: Effects of betamethasone on neuropathic pain in a rat spare nerve injury model.
abstract: The aim of the present study was to examine the effect of glucocorticoids on neuropathic pain using a rat spare nerve injury (SNI) model. Eighty rats were treated divided into the following groups: (i) a sham-operated group; (ii) a group subjected to SNI (S); (iii) a group subjected to SNI and administered 4 μg betamethasone intrathecally (D1); and (iv) a group subjected to SNI and administered 1 mg betamethasone at the site of nerve injury (D2). The mechanical withdrawal threshold (MWT) and thermal withdrawal duration (TWD) were measured 1 day before and the 1, 3, 7 and 14 days after SNI. Glial fibrillary acidic protein, glucocorticoid receptor (GR), tumour necrosis factor (TNF)-α and interleukin (IL)-1β levels in spinal cord tissue were quantified 1, 3, 7 and 14 days after SNI. The MWT was significantly higher in the D2 compared with S group 3-14 days after surgery and compared with the D1 group 7 and 14 days after surgery (P < 0.05). The TWD was significantly lower in the D2 group compared with the S and D2 groups 3-14 days after surgery (P < 0.05). Glial fibrillary acidic protein expression was significantly lower in the D1 and D2 groups compared with the S group 3-14 days after surgery (P < 0.05). Glucocorticoid receptor expression was significantly higher in the D1 group compared with the S and D2 groups after surgery (P < 0.05). Levels of TNF-α and IL-1β were significantly lower in the D1 and D2 groups compared with the S group at all time points after surgery (P < 0.05). Betamethasone suppressed astrocyte activation and increases in TNF-α and IL-1β levels in a rat model of neuropathic pain. Local injection of betamethasone resulted in smaller increases in spinal GR expression and more pronounced improvement in pain behaviour compared with intrathecal injection.
authors.affiliation: Department of Anaesthesia, The First Hospital of China Medical University, Shenyang, China. wang.qiushi@163.com
authors.forename: Qiu Shi
authors.initials: QS
authors.lastname: Wang
authors.forename: Yan Hua
authors.initials: YH
authors.lastname: Jiang
authors.forename: Tie Dong
authors.initials: TD
authors.lastname: Wang
authors.forename: Ting
authors.initials: T
authors.lastname: Xiao
authors.forename: Jun Ke
authors.initials: JK
authors.lastname: Wang
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism; D001623:Betamethasone / Q000494:pharmacology*; D004195:Disease Models, Animal; D015870:Gene Expression / Q000187:drug effects / Q000235:genetics; D005904:Glial Fibrillary Acidic Protein / Q000235:genetics / Q000378:metabolism; D007278:Injections, Spinal; D053583:Interleukin-1beta / Q000235:genetics / Q000378:metabolism; D008297:Male; D009437:Neuralgia / Q000188:drug therapy* / Q000209:etiology / Q000235:genetics / Q000378:metabolism; D010147:Pain Measurement / Q000379:methods; D010523:Peripheral Nervous System Diseases / Q000150:complications / Q000188:drug therapy; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D011965:Receptors, Glucocorticoid / Q000235:genetics / Q000378:metabolism; D013116:Spinal Cord / Q000187:drug effects / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism
chemical_list: D005904:Glial Fibrillary Acidic Protein; D053583:Interleukin-1beta; D011965:Receptors, Glucocorticoid; D014409:Tumor Necrosis Factor-alpha; D001623:Betamethasone