Repeated stress impairs endocannabinoid signaling in the paraventricular nucleus of the hypothalamus.
Endocannabinoids (eCBs) are ubiquitous retrograde signaling molecules in the nervous system that are recruited in response to robust neuronal activity or the activation of postsynaptic G-protein-coupled receptors. Physiologically, eCBs have been implicated as important mediators of the stress axis and they may contribute to the rapid feedback inhibition of the hypothalamic-pituitary-adrenal axis (HPA) by circulating corticosteroids (CORTs). Understanding the relationship between stress and eCBs, however, is complicated by observations that eCB signaling is itself sensitive to stress. The mechanisms that link stress to changes in synaptic eCB signaling and the impact of these changes on CORT-mediated negative feedback have not been resolved. Here, we show that repetitive immobilization stress, in juvenile male rats, causes a functional downregulation of CB(1) receptors in the paraventricular nucleus of the hypothalamus (PVN). This loss of CB(1) receptor signaling, which requires the activation of genomic glucocorticoid receptors, impairs both activity and receptor-dependent eCB signaling at GABA and glutamate synapses on parvocellular neuroendocrine cells in PVN. Our results provide a plausible mechanism for how stress can lead to alterations in CORT-mediated negative feedback and may contribute to the development of plasticity of HPA responses.
Wamsteeker
Jaclyn I
JI
Hotchkiss Brain Institute and Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta T2N 4N1, Canada.
Kuzmiski
J Brent
JB
Bains
Jaideep S
JS
D000818:Animals; D063385:Cannabinoid Receptor Modulators / Q000378:metabolism*; D002908:Chronic Disease; D063388:Endocannabinoids; D006624:Hippocampus / Q000503:physiopathology; D066298:In Vitro Techniques; D053444:Inhibitory Postsynaptic Potentials; D008297:Male; D009433:Neural Inhibition / Q000502:physiology; D055099:Neuroendocrine Cells / Q000502:physiology; D009474:Neurons / Q000502:physiology; D010286:Paraventricular Hypothalamic Nucleus / Q000503:physiopathology*; D017729:Presynaptic Terminals / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D043884:Receptor, Cannabinoid, CB1 / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism; D012149:Restraint, Physical; D015398:Signal Transduction; D013315:Stress, Psychological / Q000503:physiopathology*; D013569:Synapses / Q000502:physiology; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
D063385:Cannabinoid Receptor Modulators; D063388:Endocannabinoids; D043884:Receptor, Cannabinoid, CB1; D043562:Receptors, G-Protein-Coupled; D005680:gamma-Aminobutyric Acid