Neuropeptide Y (NPY) is important to countering stress and is involved in neuroadaptations that drive escalated alcohol drinking following repeated alcohol exposure in rodents. In humans, haplotype-driven diminution in NPY expression is predictive of amygdala response and emotional reactivity to stress. Genetic variation that affects the NPY system could impact resilience to stress and to developing addiction with continued alcohol use.
To determine whether functional NPY variation influences CSF NPY, behavioral adaptation to stress, and alcohol consumption in a nonhuman primate model of early adversity (peer rearing).
We sequenced the rhesus macaque NPY locus (rhNPY) and performed in silico analysis to identify functional variants. We performed gel shift assays for a −1002 T>G using nuclear extract from testes, brain and hypothalamus. Levels of NPY in CSF were measured by RIA, and mRNA levels were assessed in amygdala using RT-PCR. During infancy, animals were exposed to repeated social separation stress, and tested for individual differences in alcohol consumption as young adults. Animals were genotyped for −1002 T>G, and the effects of this variant on mRNA expression, CSF NPY, behavior arousal during stress, and ethanol consumption were assessed by ANOVA.
The G allele altered binding of regulatory proteins in all nuclear extracts tested, and −1002 T>G resulted in lower levels of NPY expression in amygdala. Macaques exposed to adversity had lower CSF NPY and exhibited higher levels of arousal during stress, but only as a function of the G allele. We also found that stress-exposed G allele carriers consumed more alcohol and exhibited an escalation in intake over cycles of alcohol availability and deprivation.
Our results suggest a role for NPY promoter variation in the susceptibility to alcohol use disorders and point to NPY as a candidate for examining GxE interactions in humans.