Dopaminergic and cholinergic modulation of the amygdala is altered in female mice with oestrogen receptor β deprivation.

The amygdala is modulated by dopaminergic and cholinergic neurotransmission, and this modulation is altered in mood disorders. Therefore, this study was designed to evaluate the presence/absence of quantitative alterations in the expression of main dopaminergic and cholinergic markers in the amygdala of mice with oestrogen receptor β (ERβ) knock-out which exhibit increased anxiety, using immunohistochemistry and quantitative methods. Such alterations could either contribute to increased anxiety or be a compensatory mechanism for reducing anxiety. The results show that among dopaminergic markers, the expression of tyrosine hydroxylase (TH), dopamine transporter (DAT) and dopamine D-like receptor (DA) is significantly elevated in the amygdala of mice with ERβ deprivation when compared to matched controls, whereas the content of dopamine D-like receptor (DA) is not altered by ERβ knock-out. In the case of cholinergic markers, muscarinic acetylcholine type 1 receptor (AChR) and alpha-7 nicotinic acetylcholine receptor (AChR) display overexpression while the content of acetylcholinesterase (AChE) and vesicular acetylcholine transporter (VAChT) remains unchanged. In conclusion, in the amygdala of ERβ knock-out female the dopaminergic and cholinergic signalling is altered, however, to determine the exact role of ERβ in the anxiety-related behaviour further studies are required.