Stress-induced modulation of endocannabinoid signaling leads to delayed strengthening of synaptic connectivity in the amygdala.
Even a brief exposure to severe stress strengthens synaptic connectivity days later in the amygdala, a brain area implicated in the affective symptoms of stress-related psychiatric disorders. However, little is known about the synaptic signaling mechanisms during stress that eventually culminate in its delayed impact on the amygdala. Hence, we investigated early stress-induced changes in amygdalar synaptic signaling in order to prevent its delayed effects. Whole-cell recordings in basolateral amygdala (BLA) slices from rats revealed higher frequency of miniature excitatory postsynaptic currents (mEPSCs) immediately after 2-h immobilization stress. This was replicated by inhibition of cannabinoid receptors (CB1R), suggesting a role for endocannabinoid (eCB) signaling. Stress also reduced N-arachidonoylethanolamine (AEA), an endogenous ligand of CB1R. Since stress-induced activation of fatty acid amide hydrolase (FAAH) reduces AEA, we confirmed that oral administration of an FAAH inhibitor during stress prevents the increase in synaptic excitation in the BLA soon after stress. Although stress also caused an immediate reduction in synaptic inhibition, this was not prevented by FAAH inhibition. Strikingly, FAAH inhibition during the traumatic stressor was also effective 10 d later on the delayed manifestation of synaptic strengthening in BLA neurons, preventing both enhanced mEPSC frequency and increased dendritic spine-density. Thus, oral administration of an FAAH inhibitor during a brief stress prevents the early synaptic changes that eventually build up to hyperexcitability in the amygdala. This framework is of therapeutic relevance because of growing interest in targeting eCB signaling to prevent the gradual development of emotional symptoms and underlying amygdalar dysfunction triggered by traumatic stress.
['Yasmin|Farhana|F|', 'Colangeli|Roberto|R|', 'Morena|Maria|M|', 'Filipski|Sarah|S|', 'van der Stelt|Mario|M|', 'Pittman|Quentin J|QJ|', 'Hillard|Cecilia J|CJ|', 'Teskey|G Campbell|GC|', 'McEwen|Bruce S|BS|', 'Hill|Matthew N|MN|', 'Chattarji|Sumantra|S|']
D000284:Administration, Oral D000581:Amidohydrolases D000818:Animals D001095:Arachidonic Acids D066272:Basolateral Nuclear Complex D063387:Cannabinoid Receptor Antagonists D004195:Disease Models, Animal D004644:Emotions D063388:Endocannabinoids D004791:Enzyme Inhibitors D019706:Excitatory Postsynaptic Potentials D006801:Humans D008297:Male D053284:Polyunsaturated Alkamides D051381:Rats D043884:Receptor, Cannabinoid, CB1 D015398:Signal Transduction D013315:Stress, Psychological
stress BLA eCB FAAH