Hypidone Hydrochloride (YL-0919), a Sigma-1 Receptor Agonist, Improves Attention by Increasing BDNF in mPFC

<b>Background/Objectives:</b> The available treatment for attention deficit is drug therapy, but the drugs show poor adverse effect profiles and individual variability in response, especially in adults. Hypidone hydrochloride (YL-0919) is a selective sigma-1 receptor agonist that demonstrated a faster onset antidepressant effect in our previous studies. Current studies aim to study the attention-enhancing effect and mechanism of YL-0919. <b>Methods:</b> We used the five-choice serial reaction time task (5-CSRTT) to measure the attention-improving effect of YL-0919 in SD rats under a physiological state and exogenous corticosterone (CORT)-exposed state. The depression/anxiety-like behavioral experiments were used in the CORT-exposed rats. Immunofluorescence staining, western blotting, and Golgi-Cox staining were used to investigate the attention-improving mechanism of YL-0919. <b>Results:</b> The studies found that intragastric administration of 2.5 and 5 mg/kg YL-0919 for 6 days significantly improved the attention of SD rats under a physiological state. CORT exposure caused depression/anxiety-like behaviors and attention deficit in the rats. Intragastric administration of 3 mg/kg SA4503 or 2.5 and 5 mg/kg YL-0919 for 6 days significantly alleviated attention deficit in SD rats under an exogenous CORT-exposed state. In addition, YL-0919 administration obviously increased the expression of BDNF, PSD95, and synapsin1 and improved the dendritic complexity and the dendritic spine density in the medial prefrontal cortex (mPFC). <b>Conclusions:</b> These results reveal that YL-0919 as a selective sigma-1 receptor agonist can significantly improve the attention of SD rats under a physiological state and exogenous CORT-exposed state. Improving the level of BDNF and dendritic complexity in the mPFC may be the important mechanisms of YL-0919 to improve attention. The study also provides a potential novel target for the drug therapy of attention deficit.