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. 2018 Aug 16;9:55-63.
doi: 10.1016/j.ynstr.2018.08.002. eCollection 2018 Nov.

Distinctive Stress Sensitivity and Anxiety-Like Behavior in Female Mice: Strain Differences Matter

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Free PMC article

Distinctive Stress Sensitivity and Anxiety-Like Behavior in Female Mice: Strain Differences Matter

Renata Cristina Nunes Marchette et al. Neurobiol Stress. .
Free PMC article

Abstract

Epidemiologic studies have shown that the prevalence of stress-related mood disorders is higher in women, which suggests a different response of neuroendocrine circuits involved in the response to stressful events, as well as a genetic background influence. The aim of this study was to investigate the baseline differences in anxiety-like behaviors of females of two commonly used mice strains. Secondly, we have also aimed to study their behavioral and biochemical alterations following stress. Naïve 3-4 months-old Swiss and C57BL/6 female mice were evaluated in the elevated plus maze (EPM) and in the acoustic startle response (ASR) for anxiety-like behaviors. Besides, an independent group of animals from each strain was exposed to cold-restraint stress (30 min/4 °C, daily) for 21 consecutive days and then evaluated in EPM and in the sucrose consumption tests. Twenty-four hours following behavioral experimentation mice were decapitated and their hippocampi (HP) and cortex (CT) dissected for further Western blotting analysis of glucocorticoid receptor (GR) and glial fibrillary acid protein (GFAP). Subsequent to each behavioral protocol, animal blood samples were collected for further plasma corticosterone analysis. C57BL/6 presented a lower anxiety profile than Swiss female mice in both behavioral tests, EPM and ASR. These phenomena could be correlated with the fact that both strains have distinct corticosterone levels and GR expression in the HP at the baseline level. Moreover, C57BL/6 female mice were more vulnerable to the stress protocol, which was able to induce an anhedonic state characterized by lower preference for a sucrose solution. Behavioral anhedonic-like alterations in these animals coincide with reduced plasma corticosterone accompanied with increased GR and GFAP levels, both in the HP. Our data suggest that in C57BL/6 female mice a dysregulation of the hypothalamus-pituitary-adrenal axis (HPA-axis) occurs, in which corticosterone acting on GRs would possibly exert its pro-inflammatory role, ultimately leading to astrocyte activation in response to stress.

Keywords: Anhedonia; Anxiety-like behavior; Depression-like behavior; Female mice; Neuroinflammation; Stress-related disorders.

Figures

Fig. 1
Fig. 1
Acoustic startle response of Swiss and C57BL/6 female mice. Behavioral responses of Swiss (clear circles) and C57BL/6 (grey circles) female mice in the acoustic startle response (ASR) at different stimulus intensities varying from 70 to 120 dB. Data are expressed as mean ± S.E.M. and analyzed by a one-way ANOVA with repeated measures followed by the Newman-Keuls´ post hoc test *p < 0.05 when compared to Swiss mice in the same stimulus (n = 24 for Swiss/n = 36 for C57BL/6).
Fig. 2
Fig. 2
Elevated plus maze exploration by Swiss and C57BL/6 female mice. Behavioral responses of Swiss (white bars) and C57BL/6 (grey bars) female mice in the elevated plus maze (EPM). (A) Percentage of time spent in the open arms. (B) Percentage of entries in the open arms. (C) Frequency of risk assessment behavior. (D) Representative occupational plot of each group generated by ANYmaze®. Vertical arms correspond to the open arms and horizontal to the enclosed arms. The hot colors represent the area most visited by the group and the cold colors, the least. Data are expressed as mean + S.E.M. and analyzed by unpaired Student's t-test *p < 0.05 (n = 10/strain). (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)
Fig. 3
Fig. 3
Plasma corticosterone levels and GR expression in Swiss and C57BL/6 female mice. (A) Plasma corticosterone levels. (B) Graphical plot of GR expression (top) and two western blot representative lanes per group (bottom), in the frontal cortex of Swiss (white bars) and C57BL/6 (grey bars). (C) Graphical plot of GR expression (top) and two western representative lanes per group (bottom), in the hippocampus of Swiss (white bars) and C57BL/6 (grey bars). GR protein (90 KDa) expression was normalized to β-actin (43 KDa) expression for each sample; A.U.: Arbitrary units. Results are expressed as mean + S.E.M. and analyzed by unpaired Student's t-test *p < 0.05 (n = 5/group).
Fig. 4
Fig. 4
Cold-restraint stress effects on EPM behavior and plasma corticosterone in Swiss and C57BL/6 female mice. Mice of both strains were exposed to one (corticosterone) or 21 days (behavior and corticosterone) of cold-restraint stress (30 min daily, 4 °C). (A) Percentage of time spent in the open arms of Swiss mice and C57BL/6 mice. (B) Percentage of entries into the open arms of Swiss mice and C57BL/6 mice. (C) Frequency of risk assessment behavior of Swiss mice and C57BL/6 mice. (D) Plasma corticosterone levels in naïve Swiss and C57BL/6 mice and in mice exposed to one or 21 days of restraint stress. CTL: control group (clear bars); STD: stressed group (streaked bars). 24 h: group submitted to one cold restraint episode of 30 min; 21 D: group submitted to cold restraint stress for 30 min daily, during 21 days. Results are expressed as mean + S.E.M. Data were analyzed by two-way ANOVA followed by Newman-Keuls’ post hoc test (EPM: n = 9–12/group for Swiss mice and n = 15/group for C57BL/6 mice; plasma corticosterone: n = 4/group). *p < 0.05 when compared to Swiss naïve group. #p < 0.05 when compared to C57BL/6 naïve group.
Fig. 5
Fig. 5
Cold-restraint stress effects on sucrose preference in Swiss and C57BL/6 female mice. Swiss (white bars) and C57BL/6 (grey bars) mice were exposed to 21 days of cold-restraint stress (30 min daily, 4 °C) and tested in the sucrose preference over water. CTL: control group (clear bars); STD: stressed group (streaked bars). Results are expressed as mean + S.E.M and analyzed by a two-way ANOVA. *p < 0.05 (n = 9–12/group for Swiss mice and n = 15/group for C57BL/6 mice).
Fig. 6
Fig. 6
Cold-restraint stress effects on GR and GFAP protein expression in the cortex and hippocampus of Swiss and C57BL/6 female mice. Swiss (white bars) and C57BL/6 (grey bars) mice were exposed to 21 days of cold-restraint stress (30 min daily, 4 °C) and euthanized after behavioral testing. Frontal cortex and hippocampus were collected and prepared for Western blotting analysis. GR expression in the (A) frontal cortex and in the (B) hippocampus. GFAP expression in the (C) frontal cortex and in the (D) hippocampus. The western lanes aligned bellow the bars graph show one representative animal of each group. GR (90 KDa) and GFAP (50 KDA) expression were normalized to β-actin (43 KDa) expression of the same samples. CTL: control group (clear bars); STD: stressed group (streaked bars); A.U.: Arbitrary units. Results are expressed as mean + S.E.M. and analyzed by two-way ANOVA followed by Newman-Keuls’ post hoc test. *p< 0.05 (n = 5/group).

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References

    1. Araya-Callís C. Chronic psychosocial stress and citalopram modulate the expression of the glial proteins GFAP and NDRG2 in the hippocampus. Psychopharmacology (Berl) 2012;224(1):209–222. - PMC - PubMed
    1. Baab J.A. Habituation of hypothalamic-pituitary-adrenocortical axis hormones to repeated homotypic stress and subsequent heterotypic stressor exposure in male and female rats. Stress. 2014;17(3):224–234. - PubMed
    1. Bangasser D.A., Valentino R.J. Sex differences in molecular and cellular substrates of stress. Cell. Mol. Neurobiol. 2012;32:709–723. - PMC - PubMed
    1. Belzung C. Innovative drugs to treat depression: did animal models fail to Be predictive or did clinical trials fail to detect effects? Neuropsychopharmacology. 2014;39(5):1041–1051. - PMC - PubMed
    1. Bhatnagar S. Lesions of the posterior paraventricular thalamus block habituation of hypothalamic-pituitary-adrenal responses to repeated restraint. J. Neuroendocrinol. 2002;14:403–410. - PubMed
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