Dopamine innervation density in four regions of the gerbil brain. Dopamine (DA) innervation density ± S.E.M. is presented in four regions of the gerbil brain, namely agranular insular and lateral orbital as well as prelimbic areas of the prefrontal cortex, the olfactory tubercle, core and shell areas of the nucleus accumbens (NAC), and the central and basolateral nuclei of the amygdala complex. Methamphetamine treatment generally tends to increase the DA innervation. However, a significant region-specific change in response to a single adult methamphetamine treatment exclusively occurs in the shell of the NAC (+11%; p = 0.0332). The difference in the core appears somewhat more pronounced but is not significant due to higher variance (+21%; p = 0.1011). Student's t-Test, significance value: * p < 0.05. Following methamphetamine treatment, ANOVA detected a significant overall increase of DA innervation in core and shell of the NAC (F(1,16) = 4.7316; p = 0.0472).