Effects of corticotrophin on pain behavior and BDNF, CRF levels in frontalcortex of rats suffering from chronic pain

AIM: To investigate the effects of corticotrophin (Cor) on corticotropin-re leasing factor (CRF), brain-derived neurotrophic factor (BDNF), and its fun ctional receptor trkB in the frontal cortex of complete Freud's adjuvant (C FA)-induced arthritic rats. METHODS: The chronic pain rat model was modifie d and pain behaviour scores were assessed. BDNF-immunoreactivity (IR), trkB -IR, and CRF mRNA-positive neurons were measured by immunohistochemistry an d in situ hybridization methods. RESULTS: Compared with control rats, pain behavior scores, BDNF-IR, CRF mRNA-positive, trkB-IR, and BDNF/CRF mRNA dou ble-labeling neurons in the contralateral frontal cortex of the arthritic m ts increased significantly at 24 h after injection of CFA (P < 0.05), and t hese effects were decreased markedly by ip injection of Cor (P < 0.05). The decrease in pain behavior and BDNF-IR,CRF mRNA levels in frontal cortex of arthritic rats due to Cor were partly prevented by adrenalectomy (ADX). CO NCLUSION: The increment in BDNF and CRF levels in the contralateral frontal cortex of arthritic rats may be inhibited by corticotrophin.