Resilience in the LPS-induced acute depressive-like behaviors: Increase of CRMP2 neuroprotection and microtubule dynamics in hippocampus.

Depressive-like behaviors occur at 24 h after lipopolysaccharide (LPS) injection, but whether the animals have resilience has not been reported. This study is to explore the existence of resilience in the LPS-induced acute depressive-like behaviors and its biological changes in the neuroprotection and microtubule dynamics. The behavioral tests of Sprague-Dawley male rats, including body weight (BW), sucrose preference test (SPT), forced swimming test (FST) and open field test (OFT), which are used to explore depressive and anxiety-like behaviors, were detected at 24 h after intraperitoneal injection of LPS. In the LPS-induced depression group, body weight and sucrose preference index in SPT were decreased, the immobility time in FST was increased, total distance, time in central zone and frequency of rearing in OFT were decreased. However, there was not any difference in behavioral phenotypes between the resilient animals and the saline control group. The activity of collapsing response mediator protein 2 (CRMP2), which is related to neuronal plasticity and neuroprotection, was increased in resilient rats. The brain-derived neurotrophic factor (BDNF) mRNA expression was also increased. The ratio of Tyr/Acet-tubulin in hippocampus, which is an important marker of microtubule dynamics, was increased without alpha-tubulin. In addition, the expression of CRMP2 and alpha-tubulin in dentate gyrus (DG) region increased in resilient animals, but not in CA1 and CA3 regions. This study firstly confirms the phenomenon of resilience in the LPS-induced acute depressive-like behaviors animal model. CRMP2 neuroprotection and microtubule dynamics in hippocampus are enhanced in this phenomenon of resilience, which may functionally contribute to resilience but need further research.