Opioid receptors have drawn highly attention to scientists since they were founded in the 1990s.As a member of G protein-coupled receptor family,opioid peptides are the endogenous ligands.It is well known to us that the basic structure consists of extracellular amino residues,seven transmembrane region and the hydroxyl residues of the cell.In recent years,the progress of science laid the foundation for further studies on the function of delta receptor.Aberrant expression of delta opioid receptor in a variety of tumors,and it plays an important role of the occurrence and development of tumors.This review describes the recent research advances on delta opioid receptor and its association with hepatocellular carcinoma.

Objective To explore the proliferation of microglia in the frontal cortex,hippocampus and amygdala of the post-stroke depression (PSD) in rats.To understand the role of microglia in the pathogenesis of PSD.Methods The adult female SD rats were divided into four groups(n=5 per group):normal control group,depression group,stroke group and PSD group.In the depression group,the depression model rat were established by chronic unpredictable mild stress (CUMS) combined with separately breeding.In the stroke group,focal cerebral ischemic rat models were established with thread embolization method.In the PSD group,focal cerebral ischemic models rat were established with thread embolization method firstly,and then PSD models rat were established with comprehensive chronic unpredictable mild stress(CUMS) and separately breeding on this basis.After the procedure,rats were subjected to sucrose preference test and open field test.At the postoperative eighth weekend,immunofluorescence technology was used to detect the proliferation changes of OX42 positive cells in the frontal lobe,hippocampus and amygdale.Results At the 29th day after CUMS,the sucrose solution consumption ((23.8±0.8) ％),horizontal movement distance of open field test ((63.0± 1.2) cm) and vertical movement distance ((25.0± 1.0) cm) in PSD group were significantly lower than those in normal group((31.2± 1.9) ％;(69.8±2.3) cm;(31.0± 1.6) cm) and depression group((31.0±1.4) ％;(70.2±2.4) cm;(30.8± 1.1) cm) (P＜0.05).The number of OX42 positive cells of frontal lobe,hippocampus and amygdale in PSD group((20.8±2.6);(20.2±1.3);(19.8±2.6))increased significantly compared with those of normal group((7.4±2.3);(8.0± 1.6);(9.4±2.1)),depression group((8.0±2.0);(7.8 ±2.2);(9.2±1.9))and stroke group((9.6±1.1);(9.4±2.2);(10.2±2.6)) (all P＜0.05).Conclusion The number of microglia in PSD group in the emotional disorders related brain areas(the frontal lobe,hippocampus and amygdale) increases obviously and the increased expression of microglia in the emotional disorders related brain areas may be responsible for the pathogenesis of PSD.

Objective To explore the expression of the CNPase positive oligodendrocytes in the frontal cortex,hippocampus and amygdala of the post-stroke depression (PSD) model rats,and to understand the role of oligodendrocytes in the pathogenesis of PSD.Methods Healthy adult SD rats were randomly divided into normal group,depression group,stroke group,and PSD group (n =5 in each group).In the stroke group,focal cerebral ischemic rat model was made with thread embolization method.In the depression group,the depression model rats were made by chronic unpredictable mild stress(CUMS) combined with separately breeding.In the PSD group,focal cerebral ischemic rat model was made with thread embolization method firstly,and then PSD rat model was established with comprehensive chronic unpredictable mild stress (CUMS) and separately breeding on this basis.After the procedure,rats were subjected to sucrose preference test (SPT) and open field test (OFT).Immunofluorescence staining was used to detect the expression of the CNPase positive oligodendrocytes in the frontal cortex,hippocampus and amygdala at day 29.Results On the 29th day after CUMS,comparing the sucrose solution consumption,horizontal movement distance of open field test and vertical movement distance of the each group,the depression((26.6± 1.1)％,(63.6±2.3)cm,(26.4±1.1)cm) and the PSD groups((23.8±0.8)％,(63.0± 1.2) cm,(25.0± 1.0) cm) were significantlylower than normal ((31.2± 1.9) ％,(69.8± 2.3) cm,(31.0 ± 1.6) cm) and the stroke groups ((31.0± 1.4) ％,(70.2±2.4) cm,(30.8 ± 1.1) cm) (P＜ 0.05).Comparing the expression of the CNPase positive oligodendrocytes in the frontal cortex,hippocampus and amygdala of the each group,the number of the stroke((16.60± 1.82),(14.60±1.82),(15.00±2.12)),depression((16.40±2.07),(14.80±2.17),(15.80±2.28)) and the PSD groups((12.40± 1.52),(11.20± 1.48),(10.80± 1.92)) were significantly less than that in normal group((20.40±3.51),(18.20±2.59),(19.00±2.55)),and the number of expression CNPase positive oligodendrocytes in the PSD group was significantly less than that in stroke and depression groups(all P＜0.05).Conclusion The number of the CNPase positive oligodendrocytes in PSD group in the emotional disorders related brain areas (the frontal lobe,hippocampus and amygdale) reduced obviously,and the oligodendrocytes may play an important role in the pathogenesis of PSD.

Objective To investigate the expressions of glial fibrilary acidic protein (GFAP) in the prefrontal cortex, hippocampus and amygdala in post-stroke depression (PSD) in rats. Methods Healthy adult SD rats w ere randomly divided into a normal group, a depression group, a stroke group, and a PSD group ( n=5 in each group). A model of focal cerebral ischemia w as induced by the intraluminal suture method in the stroke group;a rat chronic stress depression model was induced by using chronic unpredicted mild stress (CUMS) combined w ith single housing in the depression group;a model of focal cerebral ischemia w as induced by the intraluminal suture method in the PSD group. A rat PSD model w as induced by CUMS and single housing at 1 week after operation. The sucrose preference test (SPT) was performed in each group at day 1, 8, 15, and 29 after the first CUMS, and the open-field test ( OFT ) w as used to evaluate the depressive behaviors. Immunofluorescence staining was used to detect the expression of GFAP in the prefrontal cortex, and hippocampus and amygdala at day 29. Results At day 29 after CUMS, the sucrose solution consumption in SPT and the scores of horizontaland vertical movement in OFT in the depression group and PSD group w ere decreased significantly compared w ith the normal group and the stroke group (al P<0.05);the numbers of GFAP immunopositive cel s in the prefrontal cortex, hippocampus, and amygdala in the PSD group w ere significantly less than those in the normal group, depression group and stroke group (al P<0.05), and there w ere no significant differences among the normal group, depression group and stroke group (al P>0.05). Conclusion The decreased expression of GFAP in the prefrontal cortex, hippocampus, and amygdale may play a certain role in the process of PSD.

Objective To explore the expression of NT-3 and high-affinity receptors TrkC at mRNA and protein level in the prefrontal cortex of the post stroke depression(PSD)model rats.Methods Open-field method was used to evaluate the behavior.Focal cerebral ischemic rat models were made with thread em-bolization method.PSD rat models were established with comprehensive separately breeding and chronic un-predicted mild stress(CUMS)on this basis.Normal control group,depression group and stroke group were used to compare with PSD group.13 rats were used in each group.At 29th day after the CUMS RT-PCR was employed to detect gene expression of NT-3 and TrkC.The expression of NT-3 and TrkC in positive cells was detected by immunohistochemistry.Results The immunohistochemistry results showed that the number of NT-3 immunopositive cells in PSD group(10.11± 2.89)was lower than that of the normal group(19.00 ± 12.41)(P<0.05).Whereas there was no statistical difference in the other groups(P>0.05).The number of TrkC immunopositive cells in PSD group(19.56±5.66)was less than that of the normal group(25.11±3.95) and stroke group(29.67±7.38).The number of TrkC immunopositive cells in depression group(19.00±5.61)also was lower than that of the normal group(25.11±3.95)and stroke group(29.67±7.38).There was no sta-tistical difference among other groups(P>0.05).RT-PCR results showed that the GAPDH,NT-3 and TrkC mRNA in all of the groups could be detected in the prefrontal cortex of rats.The expression of NT-3 in the prefrontal cortex in the PSD group decreased significantly compared with that of normal control rats(P<0.05).There was no statistical difference in the other groups(P>0.05).The expression of TrkC in the pre-frontal cortex had no statistical difference in all of the groups(P>0.05).Conclusion The down-regulation of NT-3 and TrkC both at mRNA and protein levels in the prefrontal cortex maybe responsible for the pathogen-esis of PSD.