(2R,6R)-hydroxynorketamine acts through GluA1-induced synaptic plasticity to alleviate PTSD-like effects in rat models

• Published in: Neurobiology of stress 2022-11, Vol.21, p.100503, Article 100503
• Main Authors: Li, Yu, Du, YaLin, Wang, Chen, Lu, GuoHua, Sun, HongWei, Kong, YuJia, Wang, WeiWen, Lian, Bo, Li, ChangJiang, Wang, Ling, Zhang, XianQiang, Sun, Lin
• Format: Article
• Language: English
• Subjects: (2R,6R)-Hydroxynorketamine ((2R,6R)-HNK); GluA1; Glutamatergic nervous system; Original; Post-traumatic stress disorder (PTSD); Synaptic plasticity
• ISSN: 2352-2895; 2352-2895
• DOI: 10.1016/j.ynstr.2022.100503

Post-traumatic stress disorder (PTSD) is a debilitating mental disorder with high morbidity and great social and economic relevance. However, extant pharmacotherapies of PTSD require long-term use to maintain effectiveness and have enormous side effects. The glutamatergic system, especially the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR), is an important target of current research on the mechanism of PTSD. Postsynaptic AMPAR function and expression are known to be increased by (2R, 6R)-hydronorketamine (HNK), the primary metabolite of ketamine. However, whether (2R,6R)-HNK alleviates PTSD-like effects via AMPAR upregulation is yet to be known. In the present study, rats were exposed to single prolonged stress and electric foot shock (SPS&S). Afterwards, gradient concentrations of (2R,6R)-HNK (20, 50, and 100 μM) were administered by intracerebroventricular (i.c.v.) injection. Open field, elevated plus maze, freezing behavior, and forced swimming tests were used to examine PTSD-like symptoms. In addition, the protein levels of GluA1, BDNF and PSD-95 were analyzed using western blotting and immunofluorescence, and the synaptic ultrastructure of the prefrontal cortex (PFC) was observed by transmission electron microscopy. We found that (2R,6R)-HNK changed SPS&S-induced behavioral expression, such as increasing autonomous activity and residence time in the open arm and decreasing immobility time. Likewise, (2R,6R)-HNK (50 μM) increased GluA1, BDNF, and PSD-95 protein expression in the PFC. Changes in synaptic ultrastructure induced by SPS&S were reversed by administration of (2R,6R)-HNK. Overall, we find that (2R,6R)-HNK can ameliorate SPS&S-induced fear avoidance in rats, as well as rat cognates of anxiety and depression. This may be related to GluA1-mediated synaptic plasticity in the PFC.