[Effect of venlafaxine on cognitive function and hippocampal brain-derived neurotrophic factor expression in rats...

To evaluate the effect of venlafaxine on the cognitive impairment of learning and memory in rats with post-stroke depression (PSD) and to investigate its relationship with the expression of brain-derived neurotrophic factor (BDNF) in hippocampus.

Fifty male adult SD rats were randomly divided into control group, model group and three treatment groups (5,10, 20 mg*kg(-1) venlafaxine) with ten in each group. After the procedure of selective cerebral right middle artery embolism, a paradigm of continuous 3-week chronic unpredictable mild stress (CUMS) was used to induce PSD. Along with the course of CUMS the peritoneal injection at different dose levels of venlafaxine were performed once a day in PSD rats in a fixed time interval. Morris water maze test was applied to assess the spatial learning and memory function and immunohistochemical staining was used to detect the change of BDNF expression.

The learning function decreased significantly in PSD rats compared with the control (P<0.05), as well as in spatial exploring time (14.2 s ± 4.8 s Compared with 45.9 s ± 4.5 s) and frequency of spanning platform (1.3 ± 0.3 Compared with 8.3 ± 1.1). Moreover,very fewer BDNF positive cells were found in CA3 area of hippocampus in model group in comparison with the control group (9.8 ± 3.2 Compared with 18.5 ± 4.7). After different dosage of venlafaxine treatment, the BDNF expression and cognition increased markedly.

Venlafaxine can improve PSD-induced learning and memory dysfunction, possibly through the enhancement of the BDNF level in the CA3 area of hippocampus.