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. Author manuscript; available in PMC: 2012 Apr 1.
Published in final edited form as: Front Neuroendocrinol. 2010 Oct 15;32(2):227–246. doi: 10.1016/j.yfrne.2010.10.001

Figure 1.

Figure 1

The catecholaminergic pathway is sexually differentiated TH: Tyrosine hydroxylase, L-DOPA: L-dihydroxyphenylalanine, NE: norepinephrine. (A) Chronic physical stress results in sexually dimorphic responses. Dopamine (DA) activity is upregulated exclusively in males flight blue arrow) while norepinephrine activity is upregulated exclusively in females (yellow arrow) [58]. Only males experience impaired memory. (B) Control of TH expression differs between the sexes. SRY, the testis determining gene, which is not found in females, directly regulates TH expression in males [49; 270]. 17β-estradiol increases TH expression only in males flight blue arrows) [353]. Aromatase activity is more responsive to dihydrotestosterone (DHT) in males than in females (dark blue arrow) [354]. (C) Male rats have higher NE levels than female ones in the amygdala (A) and hypothalamus (HT) early in life [62]. When the rats reach day 300, the direction of this difference is reversed.