S. G Lindell, M. L Schwandt, H Sun, J. D Sparenborg, K Bjork, J. W Kasckow, W. H Sommer, D Goldman, J. D Higley, S. J Suomi, M Heilig and C. S. Barr
Archives of General Psychiatry, 2010, 67(4), 423-431. DOI: 10.1001/archgenpsychiatry.2010.23
Context Neuropeptide Y (NPY) counters stress and is involved in neuroadaptations that drive escalated alcohol drinking in rodents. In humans, low NPY expression predicts amygdala response and emotional reactivity. Genetic variation that affects the NPY system could moderate stress resilience and susceptibility to alcohol dependence.
Objective To determine whether functional NPY variation influences behavioral adaptation to stress and alcohol consumption in a nonhuman primate model of early adversity (peer rearing).
Design We sequenced the rhesus macaque NPY locus (rhNPY) and performed in silico analysis to identify functional variants. We performed gel shift assays using nuclear extract from testes, brain, and hypothalamus. Levels of NPY in cerebrospinal fluid were measured by radioimmunoassay, and messenger RNA levels were assessed in the amygdala using real-time polymerase chain reaction. Animals were exposed to repeated social separation stress and tested for individual differences in alcohol consumption. Animals were genotyped for –1002 T > G, and the data were analyzed using analysis of variance.
Setting National Institutes of Health Animal Center.
Subjects Ninety-six rhesus macaques.
Main Outcome Measure Behavior arousal during social separation stress and ethanol consumption.
Results 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 the amygdala. Macaques exposed to adversity had lower cerebrospinal fluid NPY levels 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.
Conclusions 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 gene x environment interactions in humans.