NPY infused into the lateral septum reduced anxiety in rats across two behavioral tests, with Y1 receptor involvement in one but not the other, suggesting multiple anxiety-reducing mechanisms.
2 of 3 tests showed anxiolysisNPY reduced anxiety in the novelty-feeding and shock-probe tests but not the elevated plus-maze, showing its anxiolytic effect in the lateral septum is context-dependent.
What the researchers found
Infusing neuropeptide Y (NPY) directly into the lateral septum — a brain region rich in NPY and involved in anxiety regulation — reduced anxiety-related behavior in rats across two of three behavioral tests.
In the novelty-induced suppression of feeding test, NPY-treated rats ate sooner in an unfamiliar environment (an anxiety measure independent of appetite changes). In the shock-probe burying test, NPY reduced defensive burying behavior. However, NPY had no effect on the elevated plus-maze.
Critically, blocking the Y1 receptor with the antagonist BIBO 3304 reversed NPY's anti-anxiety effect in the feeding test but not in the shock-probe test. This suggests NPY reduces different types of anxiety through different receptor mechanisms in the lateral septum — Y1-dependent for some anxiety behaviors and Y1-independent for others.
Why it matters
NPY is known to reduce anxiety when broadly administered to the brain, but this study pinpoints the lateral septum as a specific site of action and shows the mechanism is more complex than previously thought. Different types of anxiety appear to be regulated by different NPY receptors in the same brain region. This has implications for developing targeted anti-anxiety treatments based on neuropeptide Y pathways.
The numbers in context
1.5 μg NPY dose · BIBO 3304 at 0.15 and 0.30 μg · 3 anxiety tests · 2 of 3 tests showed anxiolysis · Y1 blockade reversed 1 of 2 effects
How the study worked
Two experiments in male Long-Evans rats. Experiment 1: NPY (1.5 μg) was infused into the lateral septum, and rats were tested on three anxiety paradigms (elevated plus-maze, novelty-induced suppression of feeding, shock-probe burying). Experiment 2: the Y1 receptor antagonist BIBO 3304 was co-infused with NPY to determine Y1 receptor involvement.
Who was studied
Male Long-Evans rats with cannulae targeting the lateral septum
What this study cannot tell us
Rat study using direct brain injection, which is not clinically practical. NPY was tested at only one dose. The elevated plus-maze showed no effect, suggesting the lateral septum's role in anxiety may be test-specific. Results may not translate directly to human anxiety disorders.
How to read the evidence
Well-designed animal study with dose-response antagonism and multiple behavioral tests. Limited by single-dose NPY testing, invasive delivery route, and incomplete receptor characterization of the non-Y1 mechanism.
When this study was published
Published in 2011, this study is part of the foundational literature on NPY and anxiety. The lateral septum's role in anxiety regulation has been further confirmed by subsequent research.
The bigger picture
This study adds anatomical precision to the well-known anti-anxiety effects of NPY. By showing that different anxiety behaviors are regulated by different NPY receptors in the same brain region, it suggests that anxiety is not a single phenomenon but involves multiple parallel neuropeptide systems. This could explain why current anti-anxiety drugs don't work for all types of anxiety and points toward more targeted peptide-based approaches.
Questions still open
- Which receptor mediates NPY's anxiolytic effect in the shock-probe test if not Y1?
- Could Y2 or Y5 receptor antagonists combined with NPY produce broader anti-anxiety effects?
- Why did NPY have no effect on the elevated plus-maze when it worked in the other two tests?
Common questions
What is the lateral septum and why does it matter for anxiety?
Why did NPY work in some anxiety tests but not others?
Read the original research
Infusions of neuropeptide Y into the lateral septum reduce anxiety-related behaviors in the rat.
Pharmacology, biochemistry, and behavior, 99(4), 580-90
Citation
Trent, Natalie L; Menard, Janet L. (2011). Infusions of neuropeptide Y into the lateral septum reduce anxiety-related behaviors in the rat.. Pharmacology, biochemistry, and behavior, 99(4), 580-90. https://doi.org/10.1016/j.pbb.2011.06.009