Dopamine and serotonin content in select brain regions of weanling and adult alcohol drinking rat lines

The objective of the present study was to examine innate differences in the tissue content of dopamine (DA), serotonin (5-HT) and their metabolites, 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA) in five brain regions of weanling and adult alcohol-preferring (P), alcohol-nonpreferring (NP), high-alcohol-drinking (HAD) and low-alcohol-drinking (LAD) selected rat lines. Adult male and weanling (postnatal day 25) male rats were killed by decapitation and brains were rapidly dissected for the following regions: olfactory tubercles (OTU), nucleus accumbens (ACB), septum (SEP), anterior cerebral cortex (ACTX) and amygdala (AMYG). Tissue extracts were assayed by HPLC with electrochemical detection. Due to significantly higher content levels in the adults, adult and weanling animals were analyzed separately. Significant differences were found in the ACB and OTU between the adult lines in both DA and 5-HT content, with P and HAD rats having lower levels than NP and LAD rats, respectively. Significant differences in DA content between the weanling lines were also found in the OTU, with P and HAD rats having lower DA levels than NP and LAD rats, respectively. These results confirm previous findings of an association between innate low DA content in select limbic regions and high alcohol drinking behavior.