Hedonic eating, obesity, and addiction result from increased neuropeptide Y in the nucleus accumbens during human brain evolution.

Bibliographic Collection: 
Publication Type: Journal Article
Authors: Raghanti, Mary Ann; Miller, Elaine N; Jones, Danielle N; Smith, Heather N; Munger, Emily L; Edler, Melissa K; Phillips, Kimberley A; Hopkins, William D; Hof, Patrick R; Sherwood, Chet C; Lovejoy, C Owen
Year of Publication: 2023
Journal: Proc Natl Acad Sci U S A
Volume: 120
Issue: 38
Pagination: e2311118120
Date Published: 2023 Sep 19
Publication Language: eng
ISSN: 1091-6490
Keywords: Animals, Behavior, Addictive, Brain, Dopamine, Ethanol, Humans, Neuropeptide Y, Nucleus Accumbens, Obesity

The nucleus accumbens (NAc) is central to motivation and action, exhibiting one of the highest densities of neuropeptide Y (NPY) in the brain. Within the NAc, NPY plays a role in reward and is involved in emotional behavior and in increasing alcohol and drug addiction and fat intake. Here, we examined NPY innervation and neurons of the NAc in humans and other anthropoid primates in order to determine whether there are differences among these various species that would correspond to behavioral or life history variables. We quantified NPY-immunoreactive axons and neurons in the NAc of 13 primate species, including humans, great apes, and monkeys. Our data show that the human brain is unique among primates in having denser NPY innervation within the NAc, as measured by axon length density to neuron density, even after accounting for brain size. Combined with our previous finding of increased dopaminergic innervation in the same region, our results suggest that the neurochemical profile of the human NAc appears to have rendered our species uniquely susceptible to neurophysiological conditions such as addiction. The increase in NPY specific to the NAc may represent an adaptation that favors fat intake and contributes to an increased vulnerability to eating disorders, obesity, as well as alcohol and drug dependence. Along with our findings for dopamine, these deeply rooted structural attributes of the human brain are likely to have emerged early in the human clade, laying the groundwork for later brain expansion and the development of cognitive and behavioral specializations.

DOI: 10.1073/pnas.2311118120
Alternate Journal: Proc Natl Acad Sci U S A