Social stress alters gene expression in a transgenerational rodent model of postnatal depression

Taliefar, Mohammad (2014) Social stress alters gene expression in a transgenerational rodent model of postnatal depression. Masters by Research thesis (MSc), Manchester Metropolitan University.

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Abstract

Maternal mood disorders such as depression and chronic anxiety can be severely detrimental to the health and wellbeing of both the affected mother and her offspring. Despite a prevalence rate of 12-15% in the UK (Segre et al. 2007), there are few animal models of postnatal depression. In this rodent model of postnatal depression and anxiety, chronic social stress exposure during lactation induces deficits in maternal care, and this stress exposure also alters the behaviour of subsequent generations. It was hypothesised that chronic social stress is an ethologically relevant form of early life stress for the developing female offspring and may have effects on subsequent adult stress related gene expression. In this study, I extend the previous findings (Nephew and Bridges, 2011) by examining several neural systems within amygdala, hypothalamic and supraoptic nucleus regions involved in the control of the stress response and expression of maternal care that may be mediating the behavioural changes in the stressed model. This research was done in collaboration with Tuft University (USA), by providing brain tissue samples from a rodent model exposed to chronic social stress during lactation and a control model (F0 generation) and their female pups were then grown (F1 generation). Using mRNA extracted from a specific region for the expression of key genes involved in regulating maternal behaviours, I analysed my research findings through Reverse transcription polymerase chain reaction. I discovered that the behavioural changes were correlated with increased corticosteroid, releasing hormone mRNA expression in the F0 central nucleus of the amygdala, increases in the expression of mineralocorticoid receptor mRNA in the F1 paraventricular nucleus, and in oxytocin receptor mRNA expression in the F1 central nucleus of the amygdala of stressed compared to control dams. In conclusion, my data supports the hypothesis that social stress during lactation has long-term effects on the maternally relevant neuropeptide systems.