Dopaminergic and cholinergic modulation of the amygdala is altered in female mice with oestrogen receptor 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 beta (ER beta) 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-2-like receptor (DA(2)) is significantly elevated in the amygdala of mice with ER beta deprivation when compared to matched controls, whereas the content of dopamine D-1-like receptor (DA(1)) is not altered by ER beta knock-out. In the case of cholinergic markers, muscarinic acetylcholine type 1 receptor (AChR(M1)) and alpha-7 nicotinic acetylcholine receptor (AChR(alpha 7)) display overexpression while the content of acetylcholinesterase (AChE) and vesicular acetylcholine transporter (VAChT) remains unchanged. In conclusion, in the amygdala of ER beta knock-out female the dopaminergic and cholinergic signalling is altered, however, to determine the exact role of ER beta in the anxiety-related behaviour further studies are required.