ΔFosB Induction in D1 Versus D2 Dopamine Neurons in the Nucleus Accumbens Following a Hormone-Simulated Pregnancy: An Exploratory Study
Haverford College. Department of Psychology
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Postpartum mood disorders (PMD) are a worldwide health concern, yet the neurobiological etiology is still widely unknown. In the present study we replicated the hormone-simulated pregnancy method developed by Liisa Galea in a novel transgenic mouse model. This approach allowed us to measure long-term genomic changes in dopaminergic plasticity in medium spiny neurons (MSNs) within the nucleus accumbens (NAc) through the transcription factor ΔFosB. We used 16 ovariectomized female transgenic mice that had fluorescent reporter molecules coupled to either D1 or D2 receptor-containing neurons; this allowed us to differentially visualize the activity of ΔFosB in each of the neuronal subtypes following a hormone-simulated pregnancy. We found a significant increase in the expression of ΔFosB in D2-MSNs in the NAc core of hormone-withdrawn animals relative to hormone-sustained animals. These neurobiological changes did not correspond with measures of anxiety in either an Elevated Plus Maze or Open Field Test. Furthermore, we found no significant changes in ΔFosB expression in D2-MSNs in the NAc shell nor in D1-MSNs in the NAc core and shell. By further understanding the influence that hormonal changes throughout pregnancy have on neurological systems, we can identify the systems that may be involved in pathological cases to develop better and more direct treatment and diagnosis options for PMD.