Neurons expressing the neuropeptide Y receptor Y5 (NPY5R) represent a key population in the hypothalamic and limbic circuits that regulate feeding behavior, energy homeostasis, and reproductive function. The NPY-Y5 receptor is one of five Y receptors (Y1, Y2, Y4, Y5, Y6) that mediate the effects of neuropeptide Y (NPY), one of the most abundant neuropeptides in the mammalian brain.
¶ Gene and Protein
| Property |
Value |
| Gene Symbol |
NPY5R |
| Chromosomal Location |
4q31.3 |
| Protein Name |
Neuropeptide Y receptor type 5 |
| UniProt ID |
P16471 |
| Protein Class |
G protein-coupled receptor (GPCR), Class A |
The NPY5R gene encodes a 456-amino acid GPCR that couples primarily to Gi/o proteins, inhibiting adenylate cyclase and reducing cAMP levels upon activation.
NPY5R contains the typical seven transmembrane domain structure of GPCRs:
- N-terminal extracellular domain: Ligand binding
- Transmembrane domains (7): Helical segments TM1-TM7
- Extracellular loops (3): ECL1-ECL3
- Intracellular loops (3): ICL1-ICL3
- C-terminal intracellular domain: G protein coupling and phosphorylation sites
NPY5R is expressed in brain regions involved in energy balance and reproduction:
- Hypothalamus: Arcuate nucleus (ARC), paraventricular nucleus (PVN), lateral hypothalamus
- Cerebral cortex: Layer-specific expression in prefrontal and entorhinal cortex
- Hippocampus: CA1-CA3 regions, dentate gyrus
- Amygdala: Basolateral and central nuclei
- Thalamus: Paraventricular and midline nuclei
- Brainstem: Nucleus tractus solitarius (NTS), area postrema
- Septal nuclei: Lateral septum
¶ Feeding and Energy Homeostasis
NPY-Y5 neurons are central to energy balance regulation:
- Orexigenic signaling: NPY binding to Y5 stimulates food intake
- Energy expenditure: Modulates metabolic rate and thermogenesis
- Fuel utilization: Influences carbohydrate versus fat metabolism
- Meal initiation: Y5 activation promotes meal onset
NPY-Y5 signaling influences reproductive physiology:
- GnRH secretion: Modulates hypothalamic-pituitary-gonadal axis
- Fertility: Y5 signaling affects reproductive success
- Puberty: Regulates timing of pubertal development
- NPY-Y5 circuits integrate circadian signals
- Food anticipatory activity mediated by Y5
- Entrainment of feeding rhythms
¶ Cognitive and Emotional Functions
- Learning and memory: Hippocampal Y5 in memory consolidation
- Anxiety: Anxiolytic effects of NPY via Y5
- Depression: NPY-Y5 in mood regulation
Involvement:
- NPY levels altered in AD brain
- Y5 receptor expression changes in hippocampus
- NPY-Y5 system affects amyloid pathology
- Relationship to appetite changes in AD
Mechanisms:
- Neuroprotective effects of NPY via Y5
- Anti-excitotoxic properties
- Modulation of neuroinflammation
Involvement:
- NPY neurons affected in PD
- Y5 signaling and motor function
- Weight loss and metabolic changes in PD
- Non-motor symptoms (sleep, mood)
Involvement:
- Altered NPY-Y5 in HD
- Metabolic dysfunction and weight loss
- Mood and behavioral changes
- Hypothalamic pathology in HD
Obesity:
- NPY5R as drug target for obesity
- Y5 antagonists reduce food intake
- Genetic variants in NPY5R and obesity risk
- Therapeutic potential of Y5 modulation
Metabolic Syndrome:
- NPY-Y5 in insulin resistance
- Dysregulated NPY in type 2 diabetes
- Therapeutic targeting
NPY5R activates multiple intracellular cascades:
- Gi/o protein signaling: Inhibition of adenylate cyclase
- MAPK pathway: ERK1/2 activation
- PI3K/Akt: Cell survival signaling
- PLC pathway: Calcium mobilization (in some cell types)
- NPY1R/NPY2R: Can form heterodimers
- Cross-talk: With leptin and melanocortin systems
- Internalization: Clathrin-dependent endocytosis
-
Y5 antagonists:
- MK-0557 (discontinued for obesity)
- NPY5R blockers in development
-
Y5 agonists:
- Potential for cachexia treatment
- Reproductive applications
-
Dual Y5/Y2 antagonists: Cledilide and analogs
- Obesity treatment: Y5 antagonists
- Cachexia: Y5 agonists
- Reproductive disorders: NPY-Y5 modulators
- Neuroprotection: NPY analog development
- NPY5R expression as metabolic marker
- CSF NPY levels in neurodegeneration
- Circuit-specific manipulation: Optogenetic targeting of NPY-Y5 neurons
- Single-cell transcriptomics: Defining NPY-Y5 neuron subtypes
- Human genetics: NPY5R variants in metabolic disease
- Therapeutic development: Brain-penetrant Y5 modulators
- NPY-Y5 receptor in energy balance (2019)
- Neuropeptide Y receptors in food intake (2020)
- NPY and Alzheimer's disease (2018)
- Hypothalamic NPY circuits in metabolism (2021)
- Y5 receptor antagonists for obesity (2017)
- NPY-Y5 in psychiatric disorders (2019)
- Neuropeptide Y and Huntington's disease (2020)
- NPY receptor signaling mechanisms (2018)