Chronic stress, as well as acute stress, reduces BDNF mRNA expression in the rat hippocampus but less robustly
Section snippets
Experimental animals
Male Sprague–Dawley rats were purchased from SLC Japan, and housed two rats per cage at least for 1 week before they were used for experiment. All animals were maintained with free access to food and tap water and under standard conditions, with lights on between 08:00 h and 20:00 h and room temperature controlled at 24 °C. All the experiments were approved by the Animal Research Committee of Wakayama Medical University and carried out in accordance with the National Institute of Health Guide for
Effects of repeated stress on the gain in body weight and HPA axis response
Rats in 1–3W-stress groups showed significant reduction in body weight gain compared to the unstressed controls. At the end of 1–3 weeks of stress period (8 weeks of age), the average body weights of rats were as follows: 302.3 ± 5.5 g (the control group), 243.7 ± 5.6 g (1W-stress group), 215.7 ± 3.9 g (2W-stress group) and 206.7 ± 4.6 g (3W-stress group). The average daily food intake in 3W-stress group was about 25% less than that in the control group. They screamed and struggled to escape for the first
Discussion
The present study has demonstrated that immediately after the last session of restraint repeated for 1–3 weeks, BDNF mRNA in the hippocampus showed significant reduction compared to the controls. Such a periodic reduction in hippocampal BDNF mRNA induced by repetitive restraints may possibly contribute to the hippocampal neuronal atrophy observed in this stress model (Watanabe et al., 1992). The hippocampal BDNF mRNA is negatively correlated with plasma GC levels. It is well documented that
Acknowledgement
This work was supported by Grant-in-Aid (13480253) for Scientific Research (B) from The Ministry of Education, Culture, Sports, Science and Technology.
References (49)
- et al.
Calretinin is present in non-pyramidal cells of the rat hippocampus—III. Their inputs from the median raphe and medial septal nuclei
Neuroscience
(1993) - et al.
Immobilization stress elevates tryptophan hydroxylase mRNA and protein in the rat raphe nuclei
Biol. Psychiatry
(2004) - et al.
Regional changes in c-fos expression in the basal forebrain and brainstem during adaptatikon to repeated stress: correlations with cardiovascular, hypothermic and endocrine responses
Neuroscience
(1995) - et al.
Bi-phasic change in BDNF gene expression following antidepressant drug treatment
Neuropharmacology
(2003) - et al.
Differential activation of the 5-hydroxytryptamine-containing neurons of the midbrain raphe of the rat in response to randomly presented inescapable sound
Neurosci. Lett.
(1995) - et al.
The effects of acute and chronic restraint stress on activation of ERK in the rostral ventromedial medulla and locus coeruleus
Pain
(2004) - et al.
Effect of chronic restraint stress and tianeptine on growth factors, growth-associated protein-43 and microtubule-associated protein 2 mRNA expression in the rat hippocampus
Brain Res. Mol. Brain Res.
(1998) - et al.
Stressful life events interacting with cognitive/personality styles to predict late-onset major depression
Am. J. Geriatr. Psychiatry
(2002) - et al.
Opposing roles for endogenous BDNF and NT-3 in regulating cortical dendritic growth
Neuron
(1997) - et al.
Chronic stress attenuates glucocorticoid negative feedback: involvement of the prefrontal cortex and hippocampus
Neuroscience
(2003)