GPR17 plays a role in ischemia-induced endogenous repair of immature neonatal cerebral White matter

Whether GPR17 has the same distribution and repair mechanism in immature white matter with periventricular leukomalacia (PVL) as in the adult brain remains to be determined. This study tried to explore the expression phase and site of GPR17, and to investigate the effect of silencing GPR17 on endogenous repair mechanism of immature white matter with PVL. Ischemic PVL in vivo results showed that GPR17 gene and protein expression increased more in the PVL than in the sham group at 12 h-24 h and 72h to 7 days after PVL. NG2⁺/GPR17⁺progenitor cells at 48 h-96 h and O4⁺/GPR17⁺precursor cells at 72h to 7d were also significantly increased in the PVL compared to the sham groups. Results in vitro showed that oxygen-glucose deprivation (OGD) also induced more GPR17 gene and protein expression than control at 48 h-72 h. There were more NG2⁺/GPR17⁺progenitor cells at 24 h-48 h and O4⁺/GPR17⁺precursor cells at 48 h-72 h in the OGD groups, as well. The functional role of GPR17 in the intrinsic repair response to ischemia was tested using GPR17 gene silencing. The progenitor cells and OL precursors in the OGD+GPR17 silencing group were both significantly less than those in the control, OGD and OGD+gene silencing control groups. The apoptotic percentage of cells in OGD+GPR17 silencing group was also much higher. In summary, ischemia-induced GPR17 expression was shown to contribute to glial-derived progenitor cell proliferation and differentiation into OL precursors, which may provide a therapeutic target for immature neonatal white matter injury after ischemia.

[Effect of single or combined application of UDP-glucose, GDNF and memantine on improvement of white matter injury in neonatal rats assessed with light and electron microscopy pathologically]

OBJECTIVE

To evaluate pathologically the effect of the single or combined application of UDP-glucose, GDNF and memantine on the improvement of white matter injury in neonatal rats with periventricular leukomalacia (PVL) under light and electron microscopy.

METHODS

A five-day-old neonatal rat model for PVL was established by ligation of the lateral common carotid artery following 120-minute hypoxia. Rats were randomly divided into six groups (30 rats in each group): sham-operated, PVL, UDP-glucose (UDP-glucose 2000 mg/kg intraperitoneally after PVL), GDNF (GDNF 100 μg/kg intracerebrally after PVL), tmemantine (memantine 20 mg/kg intraperitoneally after PVL), and a combination administration of three drugs (UDP-glucose, GDNF and memantine). The rats were sacrificed 7 or 21 days after PVL for assessment of pathological changes in the white matter under both light and electron microscopy. The number and thickness of the myelin sheath in the white matter were measured under electron microscopy, and both of pathological grading and scoring were undertaken under light microscopy.

RESULTS

There was rare and sparse myelinogenesis with a loose arrangement of nerve fibers in the white matter under electron microscopy in the PVL group at 7 and 21 days after PVL. The number and thickness of the myelin sheath in the PVL group were significantly less than in the sham-operated, UDP-glucose, GDNF, memantine and combination administration groups (P<0.01). The results of pathological grading of white matter under light microscopy showed that all rats in the PVL group manifested either mild injury (38%-50%) or severe injury (50%-62%) at 7 and 21 days after PVL. The majority of rats (50%-88%) in the four drug administration groups had normal white matter at 7 and 21 days after PVL. The pathological scores at 7 and 21 days after PVL in the PVL group were the highest, and they were significantly higher than in the other five groups (P<0.05).

CONCLUSIONS

The single or combined application of UDP-glucose, GDNF and memantine may significantly improve pathological changes in the white matter of rats with PVL. The favorable effect is inferred to be closely correlated with the improvement of brain microenvironment and the enhancement of nerve regeneration promoted by the three drugs.

Diphenyleneiodonium protects preoligodendrocytes against endotoxin-activated microglial NADPH oxidase-generated peroxynitrite in a neonatal rat model of periventricular leukomalacia

The contribution of microglial activation to preoligodendroglial (preOL) damage in the central nervous system (CNS) is considered to be one of the principal causes of periventricular leukomalacia (PVL) pathogenesis. The present study explores the effect of diphenyleneiodonium (DPI), a NADPH oxidase (NOX) inhibitor, on protection of preOLs from bacterial lipopolysaccharide (LPS)-induced microglial toxicity in vivo and in vitro. In vitro, preOLs co-cultured with microglia exhibited increased preOL apoptosis, accompanied by overproduction of superoxide anion (O(2)(-)) and the formation of peroxynitrite (ONOO(-)) after LPS exposure. LPS also significantly up-regulated accumulation of activated microglial NOX subunits p67-phox and gp91-phox in the plasma membrane. Diphenyleneiodonium (DPI) (10μm) was found to significantly attenuate up-regulation of this NOX activity. In vivo, DPI was administered (1mg/kg/day) by subcutaneous injection for 3 days to two-day-old neonatal Sprague-Dawley rats subjected to intracerebral injection of LPS. Treatment with DPI within 24h of LPS injection significantly ameliorated white matter injury, decreasing preOL loss, O(2)(-) generation, and ONOO(-) formation, and inhibiting p67-phox, gp91-phox synthesis and p67phox membrane translocation in microglia. These results indicated that LPS-induced preOL apoptosis may have been mediated by microglia-derived ONOO(-). DPI prevented this LPS-induced brain injury, most likely by inhibiting ONOO(-) formation via NOX, thereby preventing preOL loss and immature white matter injury.

[Endogenous self-repair in immature white matter induced by ischemia in neonatal rats]

OBJECTIVE

To study in vivo the endogenous self-repair mechanism in immature white matter induced by ischemia in neonatal rats with periventricular leukomalacia (PVL).

METHODS

Five-day-old neonatal Sprague-Dawley (SD) rats were randomly divided into sham and PVL groups. Rat model of PVL was prepared by ligation of the right common carotid artery following 2 hours of exposure to 8% oxygen. Pathological changes and myelination in the white matter were assessed under light and electron microscopy at 7 and 21 days after PVL. O4-positive OL precursor cells in the white matter were determined with immunofluorescence staining. Activation, proliferation, migration and differentiation of glial progenitor cells in SVZ were observed using immunofluorescent double labeling of either NG2 (marker of progenitor cells) and 5-bromodeoxyuridine (BrdU), or O4 (marker of OL precursor cells) and BrdU.

RESULTS

All rats in the PVL group manifested either mild or severe white matter injury under light microscopy, and had higher pathological scores of white matter compared with the sham group at 7 and 21 days after PVL (P<0.05). Electron microscopy showed that the number and thickness of myelin sheath in the PVL group were significantly reduced compared with the sham group (P<0.01). O4-positive OL precursor cells in the white matter observed under fluorescence microscopy were significantly reduced in the PVL group compared with the sham group (P<0.05). BrdU/NG2-positive cells in the SVZ increased significantly in the PVL group 48 hours after PVL and migrated into the periventricular area, reaching a peak on day 7 after PVL. BrdU/O4-positive newborn cells began to appear in the periventricular area 72 hours after PVL, and the number of BrdU/O4-positive cells in the PVL group was statistically more than in the sham group on day 21 after PVL (P<0.05).

CONCLUSIONS

Ischemia may induce brain self-repair in neonatal rats, resulting in activation and proliferation of NG2 glial progenitor cells in the SVZ migration and differentiation into OL precursor cells in periventricular white matter.

[Effects of glial cell line-derived neurotrophic factor and memantine on long-term prognosis in neonatal rats with periventricular leukomalacia]

OBJECTIVE

To evaluate the effects of glial cell line-derived neurotrophic factor (GDNF) and memantine on the long-term prognosis in neonatal rats with ischemia-induced periventricular leukomalacia (PVL).

METHODS

Thirty-two 5-day-old neonatal rats were randomly divided into 4 groups: sham-operated, PVL, GDNF-treated and memantine-treated. PVL was induced by right carotid artery ligation and hypoxia in the PVL, GDNF-treated and memantine-treated groups. GDNF (100 μg/kg) or memantine (20 mg/kg) was injected in the two treatment groups immediately after PVL inducement. The weight of the rats was measured immediately before and after hypoxia ischemia (HI). Both of Morris water maze test and Rivlin inclined plane test were performed at 26 days old (21 days after HI). The values of the escape latency (EL) and swimming distance, and the maximum inclined plane degree which the rats could stand at least 5 seconds were compared among the four groups.

RESULTS

The lower weight, the prolonged mean values of EL and swimming distance and the reduced maximum inclined plane degree were observed in the PVL group compared to those in the sham-operated, GDNF-treated and memantine-treated groups. There were no significant differences in the weight, the values of EI and swimming distance and the maximum inclined plane degree between the two treatment groups and the sham-operated group.

CONCLUSIONS

The administration of either GDNF or memantine can markedly increase the abilities of spatial discrimination,learning and memory, and motor coordination, promote weight gain, and improve long-term prognosis in rats with PVL.

[1400W blocks death pathway of LPS-induced activated-microglia to preOLs]

OBJECTIVE

To explore the efficacy of inductible nitric oxide synthase (iNOS) inhibitor 1400W in vivo in blocking the death pathway of lipopolysaccharide (LPS)-induced activated-microglia to preoligodendrocytes (preOLs) in neonatal rats with infective-type periventricular leukomalacia (PVL) induced by LPS.

METHODS

Two-day-old neonatal rats were randomly divided into: a sham-operated group, an untreated PVL group, and four 1400W-treated PVL groups that were subcutaneously administrated with 20 mg/kg of 1400W at 0 h, 8 hrs, 16 hrs, and 24 hrs after LPS induction, respectively. The brain specimens were obtained 5 days after LPS induction. The pathological assessment of cerebral white matter was performed under a light microscope. Concentrations of nitric oxide (NO) were measured by nitric acid-deoxidize colorimetry. Synthesis of iNOS was determined by Western blot analysis. Peroxynitrite (ONOO(-)) level and the amount of preOLs were determined by immunocytochemistry. RETHODS: The obvious injuries of periventricular white matter, massive loss of positive O4-labelled preOLs, and increased levels of NO, ONOO(-) and iNOS were observed in neonatal rats with PVL. Compared to the untreated PVL group, the use of 1400W at 0 h, 8 hrs and 16 hrs after LPS induction significantly improved white matter injuries, reduced the levels of NO, ONOO(-) and iNOS, and increased the amount of O4-labelled preOLs. However, the use of 1400W at 24 hrs after LPS induction did not result in the improvements.

CONCLUSIONS

iNOS inhibitor 1400W can effectively block the toxicity of LPS-activated microglia to preOLs and protect cerebral white matter through inhibiting iNOS and reducing the production of NO and ONOO(-). The use of 1400W within 16 hrs after LPS induction may provide cerebral protections in neonatal rats with PVL.

[Effect of 1400W, an inhibitor of inducible nitric oxide synthetase, on blocking the toxicity of lipopolysaccharide-induced activated microglia to preoligodendrocytes]

OBJECTIVE

To explore the toxicity of LPS-induced activated microglia to preoligodendrocytes (preOLs) and the effect of 1400W, a selective inhibitor of inducible nitric oxide synthetase (iNOS), on the blockage of the toxicity.

METHODS

Co-cultured microglia and preOLs obtained from two-day-old Sprague-Dawley (SD) rats were divided into three groups: co-culture control group, co-culture LPS group and co-culture LPS plus 1400W group. After cultured cells were induced by LPS (100 ng/ml) for 48 hours, the concentration of nitric oxide (NO) was measured by nitric acid-oeoxidize-colorimetry, the level of peroxynitrite (ONOO(-)) was determined by immunocytochemistry, and the synthetic level of iNOS was detected by Western blotting, respectively. The morphologic observation of apoptotic preOLs stained with Hoechst 33342/PI and the apoptotic rate of preOLs detected by flow cytometry were processed simultaneously. Data were analyzed with SPSS 11.0 software.

RESULTS

Compared to co-culture control group, there was significant increase in levels of NO [(82.27+/-3.41) micromol/L vs. (167.86+/-9.87) micromol/L, t=8.593, P<0.01], ONOO(-)[(6.14+/-1.27) x 10(7)/L vs. (34.38+/-7.75) x 10(7)/L, t=5.892, P<0.01], and iNOS [(0.18+/-0.027) vs. (0.79+/-0.068), t=9.26, P<0.01] induced by LPS in co-culture LPS group, and with a higher apoptotic rate of preOLs [(6.73+/-1.39)% vs. (24.77+/-2.05)%, t=12.619, P<0.01]. However, all levels of NO [(69.55+/-5.07) micromol/L, t=8.896, P<0.01], ONOO(-) [(10.33+/-3.47) x 10(7)/L, t=14.96, P<0.01] and iNOS (0.35+/-0.042, t=5.506, P<0.01) decreased significantly with the use of 1400W at a dose of 10 micromol/L in co-culture LPS plus 1400W group, and the apoptotic rate of preOLs [(11.8+/-2.06)%, t=7.715, P<0.01] was also reduced evidently.

CONCLUSIONS

NO, ONOO(-) and iNOS, etc. play important roles in the death pathway of preOLs induced by LPS. 1400W can block effectively the toxicity of LPS-activated microglia toxicity to preOLs through inhibiting iNOS selectively and reducing the production of NO and ONOO(-), and improve the survival rate of preOLs.

[Cerebral pathological evaluation following neural stem cells intraventricular transplantation in neonatal rats with periventricular leukomalacia]

OBJECTIVE

To evaluate the brain pathological changes following exdogenous neural stem cells (NSCs) intraventricular transplantation in neonatal rats with periventricular leukomalacia (PVL), and to explore the feasibility of NSCs transplantation for the treatment of PVL in premature infants.

METHODS

NSCs were prepared from E14 embryonic rat brain. Two-day-old neonatal rats were randomly divided into six groups: PVL, PVL+culture medium, PVL+NSCs, sham operation, sham operation+culture medium, and sham operation+NSCs (18-21 rats each group). Intraventricular transplantation of exdogenous NSCs was performed 72 hrs after PVL induction or sham operation. The cerebral pathological evaluation was undertaken by light microscopy 7, 14 and 21 days after transplantation.

RESULTS

The pathological changes in the cerebral white matter were gradually improved with the prolonged time after transplantation. After 21 days of transplantation, 50% of the cerebral white matter showed mild pathological changes and 50% of that showed severe pathological changes, with neuronal pathological scores of 1.28+/-0.86, in the untreated PVL group. In the PVL+NSCs group, 30% of normal white matter, 40% of mild and 30% of severe pathological changes in the white matter were observed, with neuronal pathological scores of 0.32+/-0.16, 21 days after transplantation. There were very significant differences in both of pathological changes in the cerebral white matter and neuronal pathological scores between the PVL and PVL+NSCs groups (x2=10.7, P<0.01; F=29.664, P<0.01).

CONCLUSIONS

Intraventricular transplantation of exdogenous NSCs can apparently improve cerebral white matter damage. It is suggested that intraventricular transplantation of NSCs is of a great potential feasibility for the treatment of PVL in premature infants.

[Establishment of a neonatal rat model of periventricular leukomalacia and its concomitant cataract]

OBJECTIVE

To establish a reliable neonatal rat model of periventricular leukomalacia (PVL) which is expected to be similar to PVL of human preterm infants pathologically, and to explore the concomitant eye lesions in the PVL model.

METHODS

Two-old-day neonatal rats were randomly divided into a PVL group and a sham-operated group (n=19 each). The PVL model was established by the ligation of bilateral common carotid arteries, followed by a 30-min exposure to 8% oxygen. The cerebral infarction area was assessed with TTC staining 1 day after operation. Cerebral pathology was examined under a light micsrocope 2 and 21 days after operation. The examinations of eyes under a slip lamp and the pathology of eyeballs under a light microscope were performed 21 days after operation.

RESULTS

The TTC staining cerebral slices showed there were extensive white areas of infarction in the brain of the PVL group, with an infarction area of 53.45 +/- 33.90 mm3 and a percentage of infarction of (24.98 +/- 15.44)% . Significant cystic necrosis and apoptosis around the periventricular and subcortical white matter and mild damage in cortical neurons were observed in the PVL group 2 days after operation. The more obvious cystic necrosis around the periventricular area was found in the PVL group 21 days after operation. There were no pathological changes in the brain of the sham-operated group. All of rats in the PVL group had bilateral cataracts, however, no pathological changes were observed in their postbulbar tissues. The sham-operated group did not show eye abnormal.

CONCLUSIONS

The PVL animal model that was similar to PVL of human preterm infants pathologically was successfully established by the ligation of bilateral common carotid arteries, followed by 30-min hypoxia exposure, with a positive effect and a good repeatability. Cataract can also be induced by the method.

[Effect of different blood glucose levels on the expression of cerebral GLUT3 mRNA in neonatal rats with hypoxia-ischemia]

OBJECTIVE

Concerns of the effect of glucose on perinatal hypoxic-ischemic brain damage are increasing. It was previously considered that the glucose transporter (GLUT) genes and their productions played an important role in the regulation of cerebral energy metabolism. The present study aimed to explore the effect of different blood glucose levels on the expression of cerebral GLUT3 mRNA in neonatal rats with hypoxia-ischemia (HI), and to evaluate the neuroprotective effect of glucose against HI insults.

METHODS

A total of 250 7-day-old neonatal SD rats were randomly divided into 10 groups (n=25 each): Normal control, Sham-operated, HI, Hypoglycemia, Hypoglycemia pre- and post-HI, Mild hyperglycemia pre- and post-HI, Severe hyperglycemia pre- and post-HI. Blood glucose levels of normal, hypoglycemia, mild hyperglycemia and severe hyperglycemia were defined as 5-7 mmol/L, 3-4 mmol/L, 10-15 mmol/L and 16-25 mmol/L, respectively. The expression of GLUT3 mRNA was detected with RT-PCT technique at 2, 24, 48 and 72 hrs and at 7 days after HI.

RESULTS

There was a correlation between increases in GLUT3 mRNA expression and postnatal age in the Normal control group. HI significantly enhanced the expression of GLUT3 mRNA from 2 hrs, peaking at 24 hrs after HI, and then significantly decreased at 72 hrs and 7 days after HI when compared with the Normal Control group (P < 0.01). GLUT3 mRNA expression in the Hypoglycemia pre-HI group was the lowest among all groups with HI at each time point after HI, and a statistically significant difference was found at 72 hrs after HI when compared with the HI group (P < 0.05). The expressional levels of GLUT3 mRNA in the Severe hyperglycemia pre-HI group were strikingly higher than those in any other groups with HI (P < 0.05 or 0.01). The GLUT3 mRNA expression patterns in the Mild and Severe hyperglycemia post-HI and the Hypoglycemia post-HI groups were similar to the Hypoglycemia pre-HI group.

CONCLUSIONS

GLUT3 mRNA expression and the synthesis of GLUT3 can be down-regulated by hypoglycemia pre-HI, coupled with aggravation of cerebral pathology, but up-regulated by higher hyperglycemia pre-HI, coupled with improvement of cerebral pathology. This suggested that adequate glucose supplement before HI can improve the cerebral function against HI insults in neonatal rats.

[Long-term effects of memantine therapy on neonatal rats with hypoxic-ischemic brain damage]

OBJECTIVE

Animal trials have demonstrated that memantine has neuroprotective effects on hypoxic-ischemic (HI) brain damage. Whether memantine can improve the long-term prognosis of rats with HI brain damage has not been reported. This study was designed to investigate the long-term effect of memantine therapy on neonatal rats with HI brain damage.

METHODS

Sixty postnatal 7-day-old newborn rats were randomly assigned into Normal control, HI and Memantine treated groups. Memantine (20 mg/kg) was administered immediately after HI in the Memantine-treated group. All subjects received a 5-day training of Morris water maze test from 23 days old. The escape latency (EL) was recorded at 28 and 35 days old.

RESULTS

The EL values of the Normal control, HI and Memantine-treated groups at 28 days old were 23.1 +/- 21.8, 35.1 +/- 5.3, and 20.6 +/- 3.4 seconds, respectively. There was a significant difference in the EL value between the HI and the Normal control groups (P < 0.05). The EL value of the Normal control, HI and Memantine-treated groups at 35 days old were 19.7 +/- 16.7, 35.6 +/- 32.3, and 16.3 +/- 13.2 seconds, respectively. A prolonged EL induced by HI still existed (P < 0.05 vs Normal controls) but memantine treatment shortened the EL (P < 0.01 vs HI group) at 35 days old.

CONCLUSIONS

Administering memantine immediately after HI can markedly increase the abilities of spatial discrimination, learning and memory and improve the long-term prognosis in rats with HI brain damage.

Inhibition of regrowth of prostatic glandular cells by epristeride

AIM

To evaluate the ability of epristeride to inhibit the prostatic glandular regrowth.

METHODS

Normal rats were castrated. Testosterone was injected to induce the regrowth of glandular cells. HE staining was performed. The height of the glandular epithelium and the acinar luminal areas were determined, and dihydrotestosterone (DHT) was detected by immunohistochemistry.

RESULTS

Both the height and the acinar luminal areas were reduced by 48 % and 55 % in epristeride-treated group compared with control group respectively. The staining of DHT was comparatively strong in the control group. After 30-d of treatment, it turned much weaker.

CONCLUSION

The regrowth of glandular cells was inhibited by epristeride via declining of the DHT concentration in the rat prostate.

Intravenous pyogenic granuloma: immunohistochemical consideration--a case report

Intravenous pyogenic granuloma is a rare form of pyogenic granuloma in which the whole lesion appears as a single polypoid mass projecting into the lumen of a vein. Histologically, this benign lesion is similar to pyogenic granuloma of other locations and is characterized by lobular proliferation of capillaries embedded in a fibromyxoid stroma. The following report illustrated the classic findings associated with an intravenous pyogenic granuloma in a young woman. A brief review of this rare entity follows the case report. Although the history and physical findings were approximately the same in each patient, they do not seem characteristic enough to allow for a definite preoperative diagnosis. The clinical differential diagnosis of intravenous pyogenic granuloma is varied and requires careful pathologic attention if excised. Complete local excision with a small portion of the vein is the treatment of choice.

Atrophy and apoptosis in ventral prostate of rats induced by 5alpha-reductase inhibitor, epristeride

AIM

To study molecular mechanism of epristeride in the treatment of benign prostatic hyperplasia and discuss the possibility of using prostate acid phosphatase (ACP) as a marker of the atrophy of prostatic gland in vivo.

METHODS

Morphological changes in cells were observed by light microscope. TdT-mediated dUTP-biotin nick end labeling (TUNEL) technique and agarose gel electrophoresis were performed to detect the nucleosomal DNA fragmentation. The activity of pACP was also assayed.

RESULTS

Apoptosis occurred in both castration- and epristeride- treatment group. Both the degree and extent of apoptosis are much larger in the group of castration than that of epristeride-treated group. Both epristeride and castration decreased the prostate wet weight and DNA content but increased the prostate DNA concentration. Maximal or near maximal decreases were seen by d 10 in both groups. The activity of ACP was decreased by both castration and epristeride treatment. Changes in the ACP activity during treatment were coincide with other changes such as the prostate wet weight and DNA content.

CONCLUSION

Apoptosis induced by epristeride was one of mechanisms in the treatment of benign prostatic hyperplasia and the activity of ACP could be used as a marker of prostate atrophy.

Inhibitory effect of nomegestrol acetate on steroidogenesis of cultured granulosa cells from rat ovary in vitro

AIM

To study the effect of nomegestrol acetate, a new synthetic progesterone on granulosa cells' viability and steroidogenesis function.

METHODS

Granulosa cells were cultured in McCoy's 5A medium. Trypan blue stain was used to measure viable cells. FSH and testosterone were added to stimulate the steroid secretion. Specific RIA assay was used to evaluate the estrogen and progesterone secretion respectively.

RESULTS

IC50 of nomegestrol acetate to damage cells is 6.85 mg/L (95 % confidence limits 5.36-8.75 mg/L). Nomegestrol acetate 0.45, 0.9, and 1.8 mg/L greatly inhibited the estrogen secretion from granulosa cells by 7.6 %, 12.5 %, 28.3 % in the presence of testosterone 0.5 micromol/L and FSH 10 U/L without affecting the number of viable cells. The secretion of progesteron were markedly decreased by 44.5 %, 53.3 %, and 62.0 % concurrently.

CONCLUSION

Nomegestrol acetate directly inhibited the steroidogenesis of granulosa cells.