To study genetic and environmental con-tributions to cerebrospinal fluid (CSF) monoamine con-centrations, 55 young rhesus monkeys (Macaca mulatta)were reared apart from their 10 fathers to perform a pa-ternal half-sibling analysis.
To study maternal genetic contributions, 23infants were reared with their mothers, 23 infants wereremoved from their mothers at birth and fostered to un-related lactating female monkeys, and 24 infants were re-moved from their mothers at birth and reared with age-matched peers. When the monkeys reached age 6 months,CSF samples were obtained via cisternal puncture priorto and during a series of social separations.
When the results were statistically pooled ac-cording to the biological father, comparisons using anal-ysis of variance indicated that both CSF 5-hydroxyin-doleacetic acid (5-HIAA) and homovanillic acid (HVA)concentrations showed significant heritable (h2) effects(h2>0.5) for both sons and daughters, whereas 3-methoxy-4-hydroxyphenylglycol (MHPG) showed a nearly signif-icant paternal genetic effect only for sons (h2>0.5). Inaddition, there were substantial maternal genetic influ-ences on the young monkeys' CSF MHPG and 5-HIAA(h2>0.5) levels. Structural equation analyses indicated amaternal genetic contribution without a maternal envi-ronmental contribution to CSF 5-HIAA concentration; onthe other hand, there was both a maternal genetic andenvironmental contribution to MHPG.
These findings suggest that a significantportion of the variance in the turnover of the monoamineneurotransmitters is determined by genetic mechanisms.