Chronic social instability stress enhances vulnerability of BDNF response to LPS in the limbic structures of female rats: A protective role of antidepressants

The aim of the present study was to estimate the influence of antidepressants given chronically on brain-derived neurotrophic factor (BDNF) alterations induced by lipopolysaccharide (LPS) in the amygdala and hippocampus of female rats subjected to chronic social instability stress (CSIS) for 29-30 days. CSIS was used as a paradigm known to be more stressful for females because stress induces affective disorders more frequently in women than men. An increased relative adrenal weight and a tendency towards the enhanced plasma corticosterone concentration were found in the stressed rats. Sucrose preference was not changed. On the last experimental day, the rats in the estrus phase were injected ip with LPS (1 mg/kg). In the stressed rats, LPS administration decreased BDNF mRNA levels in both limbic structures. Desipramine (10 mg/kg), fluoxetine (5 mg/kg) or tianeptine (10 mg/kg) given ip once daily reversed the effect of the combined stress and LPS, and tianeptine induced the strongest effects. These results indicate that chronic stress enhances vulnerability of BDNF response to deleterious influence of neuroinflammation in the examined limbic structures, what may account for its role in triggering neuropsychiatric diseases. The observed effect of antidepressants may be of significance for their therapeutic effects in the stress-induced affective disorders in females.