Prenatal stress, moderate fetal alcohol, and dopamine system function in rhesus monkeys

This study examined the striatal dopamine system integrity and associated behavior in 5- to 7-year-old rhesus monkeys born from mothers that experienced stress and/or consumed moderate levels of alcohol during pregnancy. Thirty-one young adult rhesus monkeys were derived from females randomly assigned to one of four groups: (1) control group that consumed isocaloric sucrose solution throughout gestation; (2) stress group that experienced prenatal stress (10-min removal from home cage and exposure to three random loud noise bursts, gestational days 90 through 145); (3) alcohol group that consumed alcohol (0.6 g/kg/day) throughout gestation; or (4) combined alcohol plus stress group that received both treatments. The subjects were assessed for striatal dopamine system function using positron emission tomography (PET), in which the dopamine (DA)-rich striatum was evaluated in separate scans for the trapping of [(18)F]-Fallypride (FAL) and 6-[(18)F]fluoro-m-tyrosine (FMT) to assess dopamine D2 receptor binding potential (BP) and DA synthesis via dopa decarboxylase activity, respectively. Subjects were previously assessed for non-matching-to-sample (NMS) task acquisition, with ratings of behavioral inhibition, stereotypies, and activity made after each NMS testing session. Subjects from prenatal stress conditions (Groups 2 and 4) showed an increase in the ratio of striatal dopamine D2 receptor BP and DA synthesis compared to controls (Group 1). An increase in the radiotracer distribution volume ratios (DVRs), which is used to evaluate the balance between striatal DA synthesis and receptor availability, respectively, was significantly correlated with less behavioral inhibition. The latter supports a hypothesis linking striatal function to behavioral inhibitory control.