TY - JOUR
T1 - Sex differences in basal reelin levels in the paraventricular hypothalamus and in response to chronic stress induced by repeated corticosterone in rats
AU - Sánchez-Lafuente, Carla L.
AU - Romay-Tallon, Raquel
AU - Allen, Josh
AU - Johnston, Jenessa N.
AU - Kalynchuk, Lisa E.
AU - Caruncho, Hector J.
N1 - Funding Information:
This research was supported by NSERC discovery grants to HJC and LEK, and by a CIHR-CRC to HJC.
Publisher Copyright:
© 2022 Elsevier Inc.
PY - 2022/11
Y1 - 2022/11
N2 - Repeated exposure to the stress hormone corticosterone results in depressive-like behaviours paralleled by the downregulation of hippocampal reelin expression. Reelin is expressed in key neural populations involved in the stress response, but whether its hypothalamic expression is sex-specific or involved in sex-specific vulnerability to stress is unknown. Female and male rats were treated with either daily vehicle or corticosterone injections (40 mg/kg) for 21 days. Thereafter, they were subjected to several behavioural tasks before being sacrificed to allow the analysis of reelin expression in hypothalamic nuclei. The basal density of reelin-positive cells in males was significantly higher in the paraventricular nucleus (19 %) and in the medial preoptic area (51 %) compared to females. Chronic corticosterone injections increased the immobility time in the forced swim test in males (107 %) and females (108 %) and decreased the exploration of the elevated plus maze in males (34 %). Corticosterone also caused a significant decrease in the density of reelin-positive cells in males, in both ventrodorsal (37 %) and ventrolateral (32 %) subdivisions of the paraventricular nucleus, while not affecting females. Moreover, in the paraventricular nucleus of males, 30 % of the basal reelin-positive cells co-expressed oxytocin while only 17.5 % did in females, showing a positive correlation between reelin and oxytocin levels. Chronic corticosterone did not significantly affect co-localization levels. For the first time, this study shows that there is a sexually dimorphic subpopulation of reelin-positive neurons in the paraventricular nucleus that can be differentially affected by chronic stress.
AB - Repeated exposure to the stress hormone corticosterone results in depressive-like behaviours paralleled by the downregulation of hippocampal reelin expression. Reelin is expressed in key neural populations involved in the stress response, but whether its hypothalamic expression is sex-specific or involved in sex-specific vulnerability to stress is unknown. Female and male rats were treated with either daily vehicle or corticosterone injections (40 mg/kg) for 21 days. Thereafter, they were subjected to several behavioural tasks before being sacrificed to allow the analysis of reelin expression in hypothalamic nuclei. The basal density of reelin-positive cells in males was significantly higher in the paraventricular nucleus (19 %) and in the medial preoptic area (51 %) compared to females. Chronic corticosterone injections increased the immobility time in the forced swim test in males (107 %) and females (108 %) and decreased the exploration of the elevated plus maze in males (34 %). Corticosterone also caused a significant decrease in the density of reelin-positive cells in males, in both ventrodorsal (37 %) and ventrolateral (32 %) subdivisions of the paraventricular nucleus, while not affecting females. Moreover, in the paraventricular nucleus of males, 30 % of the basal reelin-positive cells co-expressed oxytocin while only 17.5 % did in females, showing a positive correlation between reelin and oxytocin levels. Chronic corticosterone did not significantly affect co-localization levels. For the first time, this study shows that there is a sexually dimorphic subpopulation of reelin-positive neurons in the paraventricular nucleus that can be differentially affected by chronic stress.
KW - Corticosterone
KW - Depression
KW - Hypothalamus
KW - oxytocin
KW - Paraventricular nucleus
KW - Reelin
KW - Sex differences
KW - Stress
UR - http://www.scopus.com/inward/record.url?scp=85140084072&partnerID=8YFLogxK
U2 - 10.1016/j.yhbeh.2022.105267
DO - 10.1016/j.yhbeh.2022.105267
M3 - Article
C2 - 36274499
AN - SCOPUS:85140084072
SN - 0018-506X
VL - 146
JO - Hormones and Behavior
JF - Hormones and Behavior
M1 - 105267
ER -