ABSTRACT
AIM: To investigate the effects of corticotrophin (Cor) on corticotropin-releasing factor (CRF), brain-derived neurotrophic factor (BDNF), and its functional receptor trkB in the frontal cortex of complete Freud's adjuvant (CFA)-induced arthritic rats. METHODS: The chronic pain rat model was modified and pain behaviour scores were assessed. BDNF-immunoreactivity (IR), trkB-IR, and CRF mRNA-positive neurons were measured by immunohistochemistry and in situ hybridization methods. RESULTS: Compared with control rats, pain behavior scores, BDNF-IR, CRF mRNA-positive, trkB-IR, and BDNF/CRF mRNA double-labeling neurons in the contralateral frontal cortex of the arthritic rats increased significantly at 24 h after injection of CFA (P < 0.05), and these effects were decreased markedly by i.p. 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). CONCLUSION: The increment in BDNF and CRF levels in the contralateral frontal cortex of arthritic rats may be inhibited by corticotrophin.
Subject(s)
Adrenocorticotropic Hormone/pharmacology , Brain-Derived Neurotrophic Factor/metabolism , Corticotropin-Releasing Hormone/metabolism , Frontal Lobe/metabolism , Pain/metabolism , Animals , Arthritis/metabolism , Arthritis/physiopathology , Chronic Disease , Corticotropin-Releasing Hormone/genetics , Female , Male , Pain/physiopathology , Pain Measurement , RNA, Messenger/metabolism , Rats , Rats, Wistar , Receptor, trkB/metabolismABSTRACT
Substance P(SP) immunoreactivity in the rat brain and spinal cord were measured by radioimmunoassay and studied to correlate with the analgesic effect induced by electroacupuncture (EA). The results showed following: (1) There was a significant elevation in SP levels sn the hippocampus, hypothalamus and striatum after 30 min of EA. There was a markedly fall in the spinal cord. Statistical analysis revealed a positive correlation between the EA effect and the SP content in hypothalamus, striatum and statistical analysis revealed a correlation. In the spinal cord. (p less than 0.01), while the SP content in the hippocampus exhibited a similar degree of elevation in non responsive and good responsive animals to EA stimulation. (2) SP levels in the hippocampus, hypothalamus and striatum were increased by electroacupuncture stimulation (3v). The frequency of 1.5Hz was no obvious difference as compared with 100Hz in the effects on brain SP content. (3) SP content in the spinal cord decreased only using electroacupuncture stimulations of combination of higher intensity (3v) and higher frequency (100 Hz). (4) This effect could be blocked by the naloxone (i.p) and LSD (icv), but icv injection of Met-enkephalin antibodies had no affects on them.