The Stress Veto
Six different signals can veto fat release by binding their own inhibitory receptors on the fat cell: lactate, short-chain fatty acids from fiber, long-chain fatty acids the cell just released, succinate, nicotinic acid, and this one. This is the one that answers to stress. It is worth knowing because the stress hormone that drives release and the peptide that vetoes it are released together — accelerator and brake, arriving at the same moment.
In depth
The receptor through which stress signaling tells the fat cell to stop releasing — the least-known of six such brakes.
What drives it
Feeding drive increases it.
The sixth and least-known veto on fat release, and the one stress opens. Alongside lactate, short-chain fatty acids, long-chain fatty acids, succinate and nicotinic acid, neuropeptide y acts through its own Gi-coupled receptor on the fat cell: 'many of lipolysis' regulators act on the pro-lipolytic PKA pathway, which is typically activated by catecholamines and can be inhibited by different factors upon binding to their respective Gi-coupled receptors' (doi 10.3389/fphys.2022.826314). Why it matters more than the other five for a real person: this ligand rises with stress, and it is released alongside the very epinephrine that is supposed to be driving release. The accelerator and this brake arrive together. doi 10.3389/fphys.2022.826314
Fullness hormone (PYY) increases it.
10.1371/journal.pone.0040038 — from a published diagram titled 'control DE LA LIPÓLISIS EN EL adipocito HUMANO' — a human-specific control map. Its legend enumerates the whole system: 'Receptores β- y α2A-Adrenérgicos (RA); Adenilato Ciclasa (AC); proteínas G heterotriméricas (Gs y Gi); Proteína Cinasa A (PKA); Lipasa Sensible a Hormona (LSH); Receptor de Insulina (IRS-1/2); Proteína Cinasa B (PKB); Cinasa (PI3-K); Fosfodiesterasa tipo 3B (PDE-3B); GUANILATO Ciclasa (GC); Receptor de Péptidos Natriuréticos (NPR-A); Proteína Cinasa G (PKG); Lipasa de Monoglicéridos (LMG); NEUROPÉPTIDO Y (NPY) Y PÉPTIDO YY (PYY); Proteínas que enlazan lípidos en adipocito (ALBP); Ácidos Grasos No Esterificados (AGNE)' (Revista de Educación Bioquímica, UNAM — 'Control de la lipólisis en el adipocito HUMANO' (ESPAÑOL)). A seventh veto ligand, named alongside the sixth in the same legend. Peptide YY shares the same receptor family as neuropeptide Y, and it is a gut hormone released after eating — particularly in response to protein and fiber. That is the third separate mechanism by which eating shuts this system down, alongside insulin and the short-chain fatty acids that fiber fermentation produces. The fasted rule keeps earning itself. doi 10.1371/journal.pone.0040038
What it drives
It reduces The cell's go-signal.
The sixth and least-known veto on fat release, and the one stress opens. Alongside lactate, short-chain fatty acids, long-chain fatty acids, succinate and nicotinic acid, neuropeptide y acts through its own Gi-coupled receptor on the fat cell: 'many of lipolysis' regulators act on the pro-lipolytic PKA pathway, which is typically activated by catecholamines and can be inhibited by different factors upon binding to their respective Gi-coupled receptors' (doi 10.3389/fphys.2022.826314). Why it matters more than the other five for a real person: this ligand rises with stress, and it is released alongside the very epinephrine that is supposed to be driving release. The accelerator and this brake arrive together. doi 10.3389/fphys.2022.826314
It reduces Releases stored fat.
The sixth and least-known veto on fat release, and the one stress opens. Alongside lactate, short-chain fatty acids, long-chain fatty acids, succinate and nicotinic acid, neuropeptide y acts through its own Gi-coupled receptor on the fat cell: 'many of lipolysis' regulators act on the pro-lipolytic PKA pathway, which is typically activated by catecholamines and can be inhibited by different factors upon binding to their respective Gi-coupled receptors' (doi 10.3389/fphys.2022.826314). Why it matters more than the other five for a real person: this ligand rises with stress, and it is released alongside the very epinephrine that is supposed to be driving release. The accelerator and this brake arrive together. doi 10.3389/fphys.2022.826314
See it on the map
Open the causal map to follow this pathway upstream and downstream, arrow by arrow, each with its study.