[Abstract Title]. - Society for Neuroscience

Program#/Poster#: 282.18/OO25
Topic: E.06.d. Cellular actions of stress
Support: NSERC
SHRF
Title: Repeated exposure to stress produces differential effects on reelin and synaptophysin
expression in the amygdala and hippocampus
Authors: *A. L. LUSSIER 1 , H. J. CARUNCHO 2 , L. E. KALYNCHUK 1 ;
1 Psychology, Univ. Saskatchewan, Saskatoon, SK, Canada; 2 Cell Biol., Univ. of Santiago de
Compostela, Galicia, Spain
Abstract: Repeated stress is associated with extensive dendritic remodeling in the hippocampus
and amygdala. However, it is also associated with neuronal atrophy within the hippocampus and
neuronal growth in the amygdala. As chronic stress is a risk factor for depression, this has led to
the suggestion that stress-induced changes in neuronal connectivity within these structures may
be important for the development of depression. Recent studies have shown that changes in the
glycoprotein reelin may be involved in the pathophysiology of several neuropsychiatric disorders
including depression. Although reelin guides the migration of neurons during embryonic
development, new evidence has shown that it may also be important for dendritic spine plasticity
in the adult brain. Nineteen naive male rats were split into one of four groups; repeated restraint
stress (6 hrs/day), repeated corticosterone injections (CORT, 40 mg/kg, s.c.), handled, or vehicle.
The rats were treated for 21 consecutive days, and then sacrificed via transcardial perfusion. We
focused our immunohistochemical analysis on the hippocampus and amygdala. For the
hippocampus, we found that CORT treatment decreased the number of reelin positive cells
within the stratum oriens of the CA1, stratum lacunosum, and granule cell layer of the dentate
gyrus. Restraint stress had no effect. For the amygdala, we found that CORT treatment increased
reelin cells in the lateral amygdala and decreased reelin cells in the medial and cortical
amygdala. No changes were found in the basomedial, basolateral and central amygdala. Restraint
stress decreased reelin positive cells in the basolateral and cortical amygdala only. Finally,
densitometric analysis revealed that CORT treatment increased synaptophysin expression
primarily in the subgranular zone and the hilus, but restraint had no consistent effects on
synaptophysin. These results suggest that the differential effects of stress on hippocampal and
amygdala circuitry may be partly due to alterations in reelin. This may be relevant to the
pathophysiology of depression.
Disclosures: A.L. Lussier , None; L.E. Kalynchuk, None; H.J. Caruncho, None.
Poster