Decreased expression of extracellular matrix proteins and trophic factors in the amygdala complex of depressed mice after chronic immobilization stress

Abstract

BackgroundThe amygdala plays an essential role in controlling emotional behaviors and has numerous connections to other brain regions. The functional role of the amygdala has been highlighted by various studies of stress-induced behavioral changes. Here we investigated gene expression changes in the amygdala in the chronic immobilization stress (CIS)-induced depression model.ResultsEight genes were decreased in the amygdala of CIS mice, including genes for neurotrophic factors and extracellular matrix proteins. Among these, osteoglycin, fibromodulin, insulin-like growth factor 2 (Igf2), and insulin-like growth factor binding protein 2 (Igfbp2) were further analyzed for histological expression changes. The expression of osteoglycin and fibromodulin simultaneously decreased in the medial, basolateral, and central amygdala regions. However, Igf2 and Igfbp2 decreased specifically in the central nucleus of the amygdala. Interestingly, this decrease was found only in the amygdala of mice showing higher immobility, but not in mice displaying lower immobility, although the CIS regimen was the same for both groups.ConclusionsThese results suggest that the responsiveness of the amygdala may play a role in the sensitivity of CIS-induced behavioral changes in mice.

Sex differences in depressive, anxious behaviors and hippocampal transcript levels in a genetic rat model

“…Igf2 is thought to be neuroprotective (Mackay et al ), is involved in cognition and memory consolidation (Chen et al ) and upregulation of Igf2 has been implicated as mediating the antidepressant effects of dicholine succinate (Cline et al ). Further, two recent studies show decreased Igf2 expression in the amygdala or hippocampus of male rodents in response to chronic stress (Andrus et al ; Jung et al ). Slc29a3 transports adenosine into lysosomes and a sequence variation in Slc29a3 has been significantly associated with depressive disorder in women (Gass et al ).…”

The diverse functions of osteoglycin: a deceitful dwarf, or a master regulator of disease?

“…Chelyshev and colleagues (81), in a hind limb‐unloading model of bone desorption, demonstrated damage to the spinal cord in addition to changes in the bones and muscles, which paralleled a decrease in spinal OGN expression. Furthermore, in a chronic depression model in mice, OGN expression decreased in the amygdala, an important regulator of emotional behavior in mice, showing higher immobility (and thus severely depressed mice), whereas control mice and stressed mice with lower immobility (less depressed mice) had similar OGN expression (82). Further studies showed a decrease in total length of dendrites of the central amygdala neurons in depressed mice and in vitro OGN‐enhanced neurite outgrowth, implying a role for OGN in neural outgrowth in this model (83).…”

Insulin-like growth factor 2 mitigates depressive behavior in a rat model of chronic stress

“…Environmental factors appear to alter IGF2 expression in the brain, whereby they affect neuronal premise and function. Specifically, IGF2 gene expression is significantly lower in the hippocampus and amygdala after chronic restraint stress in adult rats (Andrus et al, 2012;Jung et al, 2012).…”