The Alteration of Hippocampal BDNF Expression Is Associated with Anxiety-Like Behavior Following the Injury to the Sciatic Nerve

Abstract

Background: BDNF is a critical regulator of the cognitive functions of the brain. According to the modulatory role of BDNF in the chronic pain state, this study focused on changes in BDNF expression in the hippocampus and anxiety-like behavior, following an injury to the sciatic nerve. Methods: 30 adult male Wistar rats were randomly divided into three subsets as neuropathic, sham, and control. The neuropathic pain was induced due to chronic constriction injury of the sciatic nerve. Anxiety-like behavior was observed using the open field and elevated plus-maze tests. The level of BDNF was determined by real-time polymerase chain reaction analysis. Results: The results showed that the pain threshold decreased two weeks after CCI. Simultaneously, there was a decrease in the BDNF levels (P < 0.001, F = 15. 03). In addition, the anxiety-like behaviors increased in the open field (P < 0.01, F = 25.67; P < 0.05, F = 23.02) and elevated plus-maze (P < 0.05, F = 6.01; P < 0.001, F = 5.95) tests. In the third week after CCI, the increased pain threshold was accompanied by an increase in the level of BDNF, latency to leave the first quadrant, number of rearing behaviors (P < 0.05, F = 26.07, F = 24.04), and time spent in open arms (P < 0.05, F = 5.30) while time spent in closed arms decreased (P < 0.05, F = 4.70). Conclusions: Alteration in BDNF expression is involved in CCI-induced anxiety-like behavior.