Objective To study the mechanism of β3 adrenoceptor (β3-AR) activation underlying cholesterol efflux by activating or inhibiting the β3-AR of HepG2 cells.Methods Cultured HepG2 cells were randomly divided into control group,β3-AR agonist group and β3-AR antagonist group.Serum levels of apoA-Ⅰ,apoA-Ⅱ,and β3-AR in supernatant fluid,and cholesterol,free cholesterol,cholesterol ester in HepG2 cells were measured by ELISA.Cholesterol efflux from macrophages was tested by 3H-labled cholesterol.Expressions of ABCA1 and LXRα mRNA and protein were detected by RT-PCR and Western blot respectively.Results The efflux rate of apoA-Ⅰ,cholesterol and cholesterol ester was significantly higher while the serum levels of cholesterol and cholesterol ester were significantly lower and the expression levels of ABCA1 and LXRα mRNA and protein were significantly higher in β3 AR agonist group than in control group.The serum levels of cholesterol and cholesterol ester were significantly higher while the efflux rate of cholesterol and cholesterol ester and the expression levels of ABCA1 and LXRα mRNA and protein were significantly lower in β3-AR antagonist groupt than in β3-AR agonist group (0.49±0.10 vs 1.24±0.02,0.85±0.05 vs 1.32±0.05,0.38±0.01 vs 1.45±0.20,0.08±0.01 vs 0.76±0.02,P＜0.01).Conclusion β3 AR promotes cholesterol efflux by upregulating the expression of apoA-Ⅰin HepG2 cells.

AIM:To observe the neuritogenic actions of botulinum neurotoxin serotype A heavy chain ( BoNT/A HC) on cultured Neuro-2a cells and to investigate the related signaling mechanisms for the effect of BoNT /A HC. METHODS:Neuro-2a cells were treated with different doses of BoNT/A HC (0.01, 0.1, 1 and 10 nmol/L), and then the cells were harvested at 24 h, 48 h and 72 h of BoNT/A HC exposure for detecting the neurite length and the percen-tage of the cells with neuronal processes by immunofluorescence staining .The most efficient dose of BoNT/A HC was cho-sen for exposure to Neuro-2a cells as the above.Whole cell protein was harvested at different time points for detecting the protein levels of phosphorylated ERK 1/2 ( p-ERK1/2 ) and phosphorylated Akt ( p-Akt ) by Western blot .RESULTS:Low doses of BoNT/A HC stimulated the neurite outgrowth , and increased the percentage of the cells with neurites com-pared with the negative controls (P<0.05), especially in the group with 1 nmol/L of BoNT/A HC treatment.Meanwhile, the phosphorylation of ERK 1/2 and Akt was increased after treated with BoNT/A HC.There was an increasing tendency for the phosphorylation of ERK1/2 after the exposure of the cells to BoNT/A HC.The obvious increase in p-ERK1/2 was seen from 60 min to 5 h with 1 nmol/L of BoNT/A HC treatment ( P<0.05 ) , and the increased protein level of p-Akt was mainly observed at 15 min and 60 min ( P<0.05 ) .CONCLUSION: BoNT/A HC stimulates the neuritogenesis .The neuritogenic mechanism of BoNT/A HC on Neuro-2a cells might be realized by activation of the phosphorylation of ERK 1/2 and Akt.

Objective To investigate the effect and molecular mechanism of botulinum neurotoxin serotype A (BoNT/A) heavy chain on neuron regeneration. Methods Cell culture, rats, immunofluorescence, SDS-PAGE and western blot, etc. were adopted in this study to explore the alterations of histone-3 acetylation (acetyl-H3 ) by local treatment of BoNT/A heavy chain to spinal cord injury (SCI) in rats (in vivo) or by adding it into cell culture (in vitro). Meanwhile, the relevance of acetyl-H3 to neurite out-growth based on SCI and cell culture with BoNT/A heavy chain application was approached as well. Results The application of BoNT/A heavy chain to cultured Neuro-2a cells increased the level of H3 acetylation. The increase of H3 acetylation was paralleled with the growth of neuritogenesis. Also, the neuronal treatment of BoNT/A heavy chain to SCI promoted the re-growth of neuronal processes surrounding the lesions. The growth of neuronal processes was positively correlated to the level of H3 acetylation. During the periods of BoNT/A heavy chain treatment in vivo or in vitro, the increase of H3 acetylation showed two peaks. Conclusions BoNT/A heavy chain increased the H3 acetylation, which might be one of its neuritogenic mechanisms.