Effect of chronic restraint stress on the phenotypic transition of hippocampal astrocytes and depression-like behavior in mice / 解剖学报

Objective To explore the effect of chronic restraint stress (CRS) on the phenotypic transition of hippocampal astrocytes and depression-like behavior in mice. Methods Forty eight male C57BL/6 mice were randomly divided into control groups (control), model groups (CRS) and fluoxetine(FLX) drug intervention groups (CRS+FLX), 16 for each group. The mice of the CRS group were subjected to 3 weeks chronic restraint stress. The mice of CRS + FLX group were treated with fluoxetine by intraperitoneal injection 30 minutes before restraint stress from the day 8 to day 21.

Effects of transient receptor potential vanilloid 4 inhibitor HC067047 on anxiety-like behavior in mice induced by lipopolysaccharide / 解剖学报

Objective To investigate the effect of transient receptor potential vanilloid 4 (TRPV4) inhibitor HC067047 on anxiety-like behavior in mice induced by lipopolysaccharide (LPS). Methods Totally 48 male C57BL/6 mice were randomly divided into control group (NS), model group (LPS) and drug intervention group (HC + LPS). Anxiety mouse model was established by intraperitoneal injection of 0.83 mg/kg LPS. The HC + LPS group was intraperitoneally injected with HC067047 (10 mg/kg) 30 minutes before LPS injection, and the NS group and LPS group were injected with equal volume of normal saline. Open field test and social interaction experiments were used to detect anxiety-like behaviors in each group of mice; Immunohistochemical chemistry and Western blotting were used to detect the expression of TRPV4, inducible nitric oxide synthase (iNOS), neuronal nitric oxide synthase (nNOS) and endothelial nitric oxide synthase (eNOS) in the hippocampus. Results Immunohistochemical and Western blotting experiments showed that, compared with the NS group, the expression of TRPV4 in the hippocampus of the LPS group was significantly up-regulated (P<0.0001); In the open field test, compared with the NS group, the total distance (P < 0.0001), the distance in the central area (P<0.01) and the time of in the central area mice in the LPS group reduced significantly (P< 0.01). HC067047 intervention reversed the activities of LPS model mice total distance (P < 0.05), the distance of activities in the central area (P < 0.001) and the time of in the central area (P < 0.01); In the social interaction test, compared with the NS group, the interaction time the unfamiliar mice reduced significantly in LPS group (P<0.01), which was reversed by HC067047 treatment (P< 0.01); Western blotting detection revealed that the expression of hippocampal iNOS (P<0.05), nNOS (P < 0.001), and eNOS (P < 0.001) in the LPS group were significantly higher than the NS group, which reduced remarkably by HC067047 treatment (iNOS P < 0.05, nNOS P < 0.01 and eNOS P < 0.01). Conclusion Inhibiting the expression of TRPV4 can improve the anxiety-like behavior, and this process may be related to anti-oxidative stress.

Dexmedetomidine improving complete Freund's adjuvant-induced anxiety-like and depression-like behaviour by promoting the expression of brain-derived neurotrophic factor-tyrosin kinase receptor B in mice hippocampus / 解剖学报

Objective To study the effect of dexmedetomidine (DEX), an α2- adrenoceptor agonist, on the pain-related anxiety-like and depression-like behaviour induced by complete Freund' s adjuvant (CFA) injection and its possible regulatory mechanism. Methods Thirty-six ICR female mice were randomly divided into normal saline (NS) group, CFA group and DEX + CFA group, n = 12 for each group. Chronic inflammatory pain model was established by subcutaneous injection of 10 μl CFA into the right hind limb of mice. DEX + CFA group mice were injected intraperitoneally with 0.025 mg/kg DEX 30 minutes before nociceptive behavior test, and once a day for 7 days. Von-frey fiber was used to evaluate the threshold of mechanical pain in mice, n = 12 for each group. The anxiety-like behavior of mice were detected by open field test, n = 12 for each group. Sucrose preference, tail suspension test and forced swimming test were used to detected the depression-like behavior of mice, n = 12 for each group. The expression of adrenergic receptor β2 (ADRB2), Brain-derived neurotrophic factor (BDNF), tyrosine kinase B receptor (TrkB), and glutamate receptors 1 (GluR1) and GluR2 were detected by Western blotting, n = 8 for each group. Immunohistochemical staining was used to detect the expression of recombinant doublecortin(DCX), which is a marker of newborn neurons in the hippocampus, n = 4 for each group. Results Compared with the NS group, the mechanical threshold of mice on the 1st, 3rd and 7th day after CFA injection decreased significantly (P 0.05). Compared with the NS group, the time spent in the inner ares (P<0.01), number of entering the central grid area (P<0.01) and distance travelled in the inner area (P<0.01) of CFA group mice reduced significantly, while the time (P<0.01), numbers (P < 0.05) and distance (P < 0.05) of DEX + CFA group mice entering the central grid area enhanced significantly. The result of depression-like behavior tests showed that the sucrose preference percentage (P < 0.05) reduced significantly in CFA group when compared with NS group, and the immobility time increased significantly in tail suspension test (P<0.01) and forced swimming test (P< 0.001) in CFA mice when compared with NS group, while DEX intervention could significantly increase the sucrose preference scores (P<0.05) and decreased the immobility time in tail suspension test (P<0.05) and forced swimming test (P<0.05). The result of Western blotting showed that compared with the NS group, the levels of ADRB2 (P<0.0010), BDNF (P < 0.001), TrkB (P < 0.01), GluR1 (P < 0.001) and GluR2 (P < 0.001) in the hippocampus of CFA group were significantly decreased, while DEX intervention could significantly increase the expression of ADRB2 (P<0.05), BDNF (P < 0.001), TrkB (P < 0.001), GluR1 (P < 0.001) and GluR2 (P < 0.001). Immunohistochemical result showed that compared with the NS group, the average absorbance (AA) of DCX decreased significantly in hippocampus of CFA group (P<0.05), but increased significantly in DEX+CFA group (P < 0.05). Conclusion Dexmedetomidine may promote hippocampal neurogenesis through upregulated the expression of BDNF-TrkB, thus improving CFA-induced anxiety-like and depression-like behaviors in mice.

Effect and mechanism of bromodomain-containing protein 4 inhibitor JQl on formaldehyde solution induced inflammatory pain in mice / 解剖学报

Objective To explore the expression and role of bromodomain-containing protein 4(BRD4) in spinal cord of mice which suffered inflammatory pain induced by formaldelryde solution. Methods Thirty-two ICR mice were randomly divided into normal saline group and formaldehyde injection 5 minutes, 30 minutes and 60 minutes groups, with 8 mice in each group. The expression of BRD4 protein and mRNA in spinal cord of mice in each group were detected by Western blotting (n = 4/group) and Real-time PCR (n = 4/group); 66 mice were randomly divided into formaldelryde injection group, vehicle (DMSO) plus formaldelryde injection group and 6. 25, 12. 5, 25 and 50 mg/kg JQl injection plus formaldelryde solution group, with 11 mice in each group. The effect of BRD4 inhibitor JQl on spontaneous pain in each group was observed (n= 11/group); Immunohistochemistry (n= 3/group), Real-time PCR (n = 4/group) or Western blotting (n= 4/group) were used to detect the effects of 25 mg/kg JQ1 on the expression of c-fos and glutamate receptor 2 (GluR2) in the spinal cord of model mice. Results The result showed that levels of BRD4 protein (P<0. 01) and mRNA in spinal cord increased significantly 30 min and 60 min after formaldehyde solution injection (P<0. 05). The behavioral test showed that both 25 mg/kg and 50 mg/kg JQf administration could reduce the second phase spontaneous pain compared with the solvent (DMSO) group (P < 0 . 05). Furthennore, immunohistochemistry and Real-time PCR result showed that 25 mg/kg JQf injection could significantly reduce positive numbers (P<0. 01) and high mRNA expression of c-fos in mouse spinal cord induced by formaldehyde solution (P < 0 . 05), and the Western blotting result showed that 25 mg/kg JQf administration could significantly reduce the expression of glutamate receptor GluR2 (P < 0. OOf). Conclusion BRD4 may play an important role in the induction of central sensitization of inflammatory pain, and JQf may alleviate inflammatory pain behavior by inhibiting the formation of central sensitization of pain.

Voluntary wheel running prevents the formaldehyde induced negative emotion through up-regulation of hippocampal neurogenesis in mice / 解剖学报

Objective To investigate the effect of voluntary wheel running on negative affective of mice induced by formaldehyde. Methods Thirty male Kunming mice were randomly divided into three groups, including normal saline control group (NS), formaldehyde model group (F), and voluntary wheel running with formaldehyde injection group ( R+ F). The pain model was established by right hindpaw intraplantar formalin injection, the mice of R+F group experienced voluntary wheel running for three weeks before intraplantar formaldehyde injection. The spontaneous pain behavior was determined by the cumulative time of licking paw. The anxiety-like behavior of each group was determined by open field test (OFT) and elevated plus-maze test (EPM) while the depression-like behavior of each group was determined by forced swimming test (FST). The expression of doublecortin ( DCX ) in the hippocampus was determined by immunohistochemistry. Results Compared with the NS group, the typical two-phase pain response was observed in the F group, and compared with the F group, the second phase pain duration was significantly reduced in the R+F group (P<0. 01). In the open field test, the F group showed remarkably reduced time in the inner area(P<0. 001) compared with the NS group, while the R+F group increased time in the inner area (P<0. 05) compared with the F group. In the elevated plus-maze test, the F group showed remarkably reduced time (P< 0. 001) spent in the open arm compared with the NS group, however, compared with the F group, R+F group increased time spent in the open arm (P<0. 05). In the forced swimming test, the immobility time of the F group significant increased (P<0. 01) compared with the NS group, which was decreased in the R+F group (P<0. 05). The Immunohistochemistry showed that the area of DCX positive cells in the hippocampus of the F group was downregulated compared with the NS group, which was upregulated in the R+F group. Conclusion Our findings indicate that voluntary wheel running can improve anxiety and depression-like in mice induced by formaldehyde injection, which may be related to enhanced neurogenesis in the hippocampus.

Dexmedetomidine alleviates formaldehyde induced pain by inhibiting astrocytes activation in spinal cord / 解剖学报

Objective To investigate the effect of dexmedetomidine ( DEX ) on formaldehyde-induced acute inflammatory pain. Methods Thirty female ICR mice were randomly divided into three groups, including normal saline control (NS) group, formaldehyde(F)group and dexmedetomidine + formaldehyde (DEX+F) group. 0. 1% formaldehyde solution was injected into subcutaneous tissue of mice right hind paw to establish acute inflammatory pain model. An hour before formalin injection, mice were intraperitoneal injected with DEX in DEX + F group, and mice were intraperitoneal injected with equal volume saline in NS group and F group. The expression of spinal cord glial fibrillary acidic protein ( GFAP), which is a astrocytes marker, was detected by immunohistochemistry and Western blotting. Results Spontaneous pain score showed that compared with the NS group, the F group had typical biphasic pain response ; while compared with the F group, the DEX+F group showed a significant decrease in the first (P<0. 001) and second phase pain (P<0. 001). Immunohistochemical result showed that compared with the NS group, the F group had an increase number of GFAP positive cells in the posterior horn of the spinal cord (P<0. 001). However, the DEX+F group showed a decrease number of GFAP positive cells in the posterior horn of spinal cord compared with the F group (P<0. 001 ). Western blotting result showed that compared with the NS group, the F group had increased expression of GFAP in the spinal cord (P<0. 05). Compared with the F group, the DEX + F group showed decreased GFAP expression in the spinal cord ( P < 0. 05 ). Conclusion DEX may improve formaldehyde-induced acute inflammatory pain in mice by inhibiting the activation of astrocytes in the spinal cord.

Environmental enrichment ameliorates lipopolysaccharide-induced cognitive impairment by inhibiting NOD-like recepter protein 3 in fla mmasome activation in mice / 解剖学报

Objective To investigate the effect of environmental enrichment (EE) on lipopolysaccharide (LPS) induced cognitive dysfunction in mice. Methods A total of thirty six 3 weeks old Kunming mice experienced 8 weeks of EE or standard environment (SE) feeding. After 8 weeks, they were divided into three groups: standard environment+ normal saline (SE+NS) group, standard environment+lipopolysaccharide (SE+LPS) group, environmental enrichment+ lipopolysaccharide (EE+LPS) group. The open field test was used to measure the locomotive of mice, and the cognitive function was determined by novelty object recognition test. The expression of microglial marker ionized calcium binding adaptor molecule-1 (IBA-1) in hippocampus was determined by immunohistochemical staining. The expression of microglial activation marker CD68 and NOD-like receptor protein 3 (NLRP3) inflammasome related protein in the hippocampus was detected by Western blotting. Results In the open field test, there was no difference in the activity among the three groups. Compared with the SE + NS group, SE + LPS group showed decreased discrimination ratio in novelty object recognition task, with remarkably up-regulated expression of CD68 in the hippocampus (P< 0. 01) . In addition, SE+LPS group exhibited significantly enhanced expression of NLRP3, apoptosis associated speck-like protein (ASC), Caspase-1 and interleukin-1β(IL-1β) in the hippocampus compared with SE + NS group (P < 0. 05) . Compared with the SE + LPS group, EE+LPS group showed enhanced discrimination ratio in the object recognition task, with down-regulated expression of CD68, NLRP3, ASC, Caspase-1, IL-1β and IL-18 in the hippocampus (P < 0. 01) . Conclusion Environmental enrichment can alleviate LPS induced cognitive dysfunction, which might be attributed to the inhibiting of microglia and NLRP3 activation in the hippocampus.

Dynamic expression of insulin￣like growth factor 2 during critical period of visual development in lateral geniculate body of mice / 解剖学报

Objective To detect the dynamic expression of insulin-like growth factor 2 (IGF2) in lateral geniculate body (LGB) during the critical period of visual development. Methods Three groups of Kunming mice of different ages were selected for testing, which were 3 weeks old, 5 weeks old and 7 weeks old, twelve in each group. The forepaw-reaching reflex test was used to detect whether the visual function of the mice was normal in each group. Immunohistochemical technique was used to detect the expression of IGF2 protein and its receptor in the lateral geniculate body of normal mice at week 3, 5 and 7 postnatal, and to analyze the expression of the protein of IGF2 and its receptor in each part of the lateral geniculate body. Results The expression of IGF2 protein in the dorsal lateral geniculate nucleus decreased significantly at week 5 postnatal and increased significantly at week 7 postnatal, and increased gradually over time at week 5 and week 7 postnatal in the ventral geniculate nucleus. The expression of IGF2 receptor protein in the dorsal lateral geniculate nucleus and ventral nucleus increased significantly at week 5 postnatal, and at week 7 postnatal, the expression of IGF2 receptor decreased to week 3 level in lateral geniculate body of mice. Conclusion The expression of IGF2 and its receptor in lateral geniculate body of mice during critical period of visual development changed dynamically, and the expression patterns of IGF2 and its receptor in different parts of LGB were not completely consistent. The expression of IGF2 and its receptors may be related to the plasticity of visual development in mice.

Formaldehyde induced acute inflammation pain leads to enhanced expression of BRD 4 in spinal cord of mice / 基础医学与临床

Objective To investigate the expression of BRD 4 in the spinal cord and its relationship with acute in-flammation pain induced by formaldehyde in mice.Methods Thirty-six mice were randomly divided into three groups:control group,formaldehyde group and indomethacin+formaldehyde group;25 μL 1%formaldehyde was injected into the right plantar to establish the acute inflammationpain model,while the indomethacin(20 mg/kg) was injected intraperitoneally 1 hour before formaldehyde injection.Then,all the mice were video recored for 1h to observe the spontaneous pain.Then,cell localization of BRD4 in the spinal cord of normal mice was determined by immunofluorescence assasy.The expression of BRD4 in spinal cord was detected by immunohistochemistry and Western blot.Results Immunofluorescence showed that BRD 4 was mainly co-locolized with the neuronal marker NeuN in the spinal cord of normal mice.Formaldehyde injection could induce two-phase spontaneous pain, while indomethacin intervention could only decrease the second phase pain(P<0.05).Furthermore,formaldehyde injec-tion led to significantly enhanced expression of BRD 4 in bilateral spinal cord,which was remarkbly inhibited by in-domethacin(P<0.05).Conclusions Up-regulation of BRD4 in spinal dorsal horn may be involved in the acute in-flammatory pain.