ABSTRACT
OBJECTIVE Cranial radiotherapy is clinically used in the treatment of brain tumors;however, the conse?quent cognitive and emotional dysfunctions seriously impair the life quality of patients. LW-AFC, an active fraction combi?nation extracted from classical traditional Chinese medicine prescription Liuwei Dihuang decoction, can improve cogni?tive and emotional dysfunctions in many animal models;however, the protective effect of LW-AFC on cranial irradiation-induced cognitive and emotional dysfunctions has not been reported. Recent studies indicate that impairment of adult hippocampal neurogenesis (AHN) and alterations of the neurogenic microenvironment in the hippocampus constitute crit?ical factors in cognitive and emotional dysfunctions following cranial irradiation. Here, our research further investigated the potential protective effects and mechanisms of LW-AFC on cranial irradiation-induced cognitive and emotional dys?functions in mice. METHODS LW-AFC (1.6 g·kg-1) was intragastrically administered to mice for 14 d before cranial irra?diation (7 Gyγ-ray). AHN was examined by quantifying the number of proliferative neural stem cells and immature neu?rons in the dorsal and ventral hippocampus. The contextual fear conditioning test, open field test, and tail suspension test were used to assess cognitive and emotional functions in mice. To detect the change of the neurogenic microenvi?ronment, colorimetry and multiplex bead analysis were performed to measure the level of oxidative stress, neurotrophic and growth factors, and inflammation in the hippocampus. RESULTS LW-AFC exerted beneficial effects on the contex?tual fear memory, anxiety behavior, and depression behavior in irradiated mice. Moreover, LW-AFC increased the num?ber of proliferative neural stem cells and immature neurons in the dorsal hippocampus, displaying a regional specificity of neurogenic response. For the neurogenic microenvironment, LW-AFC significantly increased the contents of superox?ide dismutase, glutathione peroxidase, glutathione, and catalase and decreased the content of malondialdehyde in the hippocampus of irradiated mice, accompanied by the increase in brain-derived neurotrophic factor, insulin-like growth factor-1, and interleukin-4 content. Together, LW-AFC improved cognitive and emotional dysfunctions, promoted AHN preferentially in the dorsal hippocampus, and ameliorated disturbance in the neurogenic microenvironment in irradiated mice. CONCLUSION LW-AFC ameliorates cranial irradiation-induced cognitive and emotional dysfunctions, and the underlying mechanisms are mediated by promoting AHN in the dorsal hippocampus and improving the neurogenic micro?environment. LW-AFC might be a promising therapeutic agent to treat cognitive and emotional dysfunctions in patients receiving cranial radiotherapy.
ABSTRACT
OBJECTIVE To explore the effect and mechanisms of LW-AFC,a new formula derived from Liu Wei Di Huang Tang,on irradiation-induced reduction of mice adult hippocampal neurogenesis. METHODS C57BL/6J mice were randomly divided into seven groups (n=10): control group, LW-AFC group (1.6 g·kg-1), Liu Wei Di Huang Tang (LW) group (10 g·kg-1), brain derived neurotrophic factor (BDNF) group, irradiation group, irradiation+LW group, and irradiation+LW-AFC group. Reduction of mice adult hippocampal neurogenesis was induced by cranial irradiation.LW-AFC was administered by oral gavage for 30 d after cranial irradiation treatment. Immunofluorescence and Nissl′s staining were performed for histological morphology assessment. Bromodeoxyuridine (BrdU) staining was used in the detection of proliferation cells. The peripheral blood and hippocampal homogenate were collected to measure the content of tumor necrosis factor-α (TNF-α), interferon-gamma (INF-γ), interleukin-1β (IL-1β),IL-4 and IL-10.The hippocampal homogenate was used for Western blot to detect the BDNF-TrkB signal pathway, including extracellular regulated protein kinases1/2 (ERK1/2) and BDNF target protein. Morris water maze and new object recognition test were performed to examine the cognitive function of mice.The mice forced swimming and tail suspension test were used to assess alteration in depressive behavior. Long term potentiation was used to examine the synaptic plasticity change of mice. RESULTS Adult hippocampal neurogenesis was significantly reduced after irradiation of 20 Gray dose (10 Gray per day, total 2 d). LW-AFC treatment increased the BrdU number of irradiated mice (P<0.05). In Morris water maze test, LW-AFC group showed decreased escape latency in the learning period (P<0.05), while increased the number of crossing the platform in the memory period. LW-AFC can also reduce the immobility time of mice in the tail suspension test (P<0.01). CONCLU-SION LW-AFC modulates adult neurogenesis to ameliorate cognitive impairment and reduce depres-sive behavior in radiation injury mice.