Ketamine administration causes cognitive impairment by destroying the circulation function of the glymphatic system.

Ketamine, a drug originally used as an anesthetic and now commonly abused in China, can cause cognitive impairment by disrupting the brain's glymphatic system, which normally clears metabolic waste. In a mouse model of short-term ketamine administration, the drug increased expression of the 5-HT2c receptor in hippocampal astrocytes, leading to accumulation of the transcription factor ΔFosb. ΔFosb then bound to a specific DNA sequence in the regulatory region of the Aqp4 gene, suppressing Aqp4 expression and impairing glymphatic circulation, which resulted in cognitive deficits. This mechanism does not involve the Pten/Akt pathway and reveals a non-neuronal basis for ketamine-induced cognitive harm, informing clinical safety and withdrawal effectiveness.

Study at a glance

Abstract

Ketamine, as a non-competitive antagonist of N-methyl-D-aspartate (NMDA) receptors, was originally used in general anesthesia. Epidemiological data show that ketamine has become one of the most commonly abused drugs in China. Ketamine administration might cause cognitive impairment; however, its molecular mechanism remains unclear. The glymphatic system is a lymphoid system that plays a key role in metabolic waste removal and cognitive regulation in the central nervous system. Focusing on the glymphatic system, this study evaluated the behavioral performance and circulatory function of the glymphatic system by building a short-term ketamine administration model in mice, and detected the expression levels of the 5-HT2c receptor, ΔFosb, Pten, Akt, and Aqp4 in the hippocampus. Primary astrocytes were cultured to verify the regulatory relationships among related indexes using a 5-HT2c receptor antagonist, a 5-HT2c receptor short interfering RNA (siRNA), and a ΔFosb siRNA. Ketamine administration induced ΔFosb accumulation by increasing 5-HT2c receptor expression in mouse hippocampal astrocytes and primary astrocytes. ΔFosb acted as a transcription factor to recognize the AATGATTAAT bases in the 5' regulatory region of the Aqp4 gene (-1096 bp to -1087 bp), which inhibited Aqp4 expression, thus causing the circulatory dysfunction of the glymphatic system, leading to cognitive impairment. Although this regulatory mechanism does not involve the Pten/Akt pathway, this study revealed a new mechanism of ketamine-induced cognitive impairment in non-neuronal systems, and provided a theoretical basis for the safety of clinical treatment and the effectiveness of withdrawal.