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Stress rapidly dysregulates the glutamatergic synapse in the prefrontal cortex of cocaine‐withdrawn adolescent rats
Author(s) -
Caffino Lucia,
Calabrese Francesca,
Giannotti Giuseppe,
Barbon Alessandro,
Verheij Michel M. M.,
Racagni Giorgio,
Fumagalli Fabio
Publication year - 2015
Publication title -
addiction biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.445
H-Index - 78
eISSN - 1369-1600
pISSN - 1355-6215
DOI - 10.1111/adb.12089
Subject(s) - glutamatergic , prefrontal cortex , neuroscience , postsynaptic potential , glutamate receptor , neurochemical , synapse , excitatory postsynaptic potential , neurotransmission , silent synapse , psychology , medicine , inhibitory postsynaptic potential , receptor , cognition
Abstract Although several lines of evidence have shown that chronic cocaine use is associated with stress system dysregulation, the underlying neurochemical mechanisms are still elusive. To investigate whether the rapid stress‐induced response of the glutamatergic synapse was influenced by a previous history of cocaine, rats were exposed to repeated cocaine injections during adolescence [from postnatal day ( PND ) 28–42], subjected to a single swim stress (5 minutes) three days later ( PND 45) and sacrificed 15 minutes after the end of this stressor. Critical determinants of glutamatergic homeostasis were measured in the medial prefrontal cortex ( mPFC ) whereas circulating corticosterone levels were measured in the plasma. Exposure to stress in saline‐treated animals did not show changes in the crucial determinants of the glutamatergic synapse. Conversely, in cocaine‐treated animals, stress dynamically altered the glutamatergic synapse by: (1) enhancing the presynaptic vesicular mediators of glutamate release; (2) reducing the transporters responsible for glutamate clearance; (3) increasing the postsynaptic responsiveness of the N ‐methyl‐ D ‐aspartate subunit GluN1; and (4) causing hyperresponsive spines as evidenced by increased activation of the postsynaptic cdc 42‐ P ak pathway. These findings indicate that exposure to cocaine during adolescence sensitizes mPFC glutamatergic synapses to stress. It is suggested that changes in glutamatergic signaling may contribute to the increased sensitivity to stress observed in cocaine users. Moreover, glutamatergic processes may play an important role in stress‐induced reinstatement of cocaine seeking.