Tongluoxingnao effervescent tablets ameliorate learning and memory impairment in a rat model of vascular dementia via the regulation of the p38 and ERK MAPK signaling pathways

Tongluoxingnao (TLXN) effervescent tablets consist of Scutellaria baicalensis Georgi, Radix Angelicae Sinensis, and Ligusticum chuanxiong Hort that can improve cognitive dysfunction in dementia. This study aimed to evaluate the effect of TLXN on learning and memory impairment in vascular dementia (VD) rats’ model, explore the effect of the MAPK signaling pathway on chronic ischemia, and determine the underlying mechanism. VD was induced in rats by permanent occlusion of the bilateral common carotid arteries. The Morris water maze and histopathological examinations were used to evaluate the effect of TLXN on learning and memory impairment, whereas real-time PCR and Western blot analysis were used to determine the levels of mRNA and phosphorylation of members of the MAPK signaling pathway, respectively. Compared to rats in the sham group, VD rats exhibited learning and memory impairments such as escape latency prolongation and decreases in the times of entrance into the first quadrant, valid region and escape platform; however, these conditions improved following TLXN administration. Moreover, TLXN may regulate the p38 MAPK and extracellular signal-regulated kinase (ERK) signaling pathways via the inhibition of the phosphorylation of p38 MAPK (p38), ERK1/2, MAP kinase kinase 6 (MKK6), and c-jun and a reduction in the mRNA levels of p38, ERK1/2, and c-jun. These results suggest that TLXN demonstrates the potential for development as a drug for vascular dementia and that the underlying mechanism involves the regulation of the p38 and ERK MAPK signaling pathways.