Subventricular Zone Of Neonatal Rats Research Articles

NMDA receptors promote neurogenesis in the neonatal rat subventricular zone following hypoxic‑ischemic injury.

Evidence suggests the involvement of N-methyl-D-aspartate receptors (NMDAR) in the regulation of neurogenesis. Functional properties of NMDAR are strongly influenced by the type of NR2 subunits in the receptor complex. NR2A- and NR2B-containing receptors are expressed in neonatal fore-brain regions, such as the subventricular zone (SVZ). The aim of the present study was to examine the effect of the protein expression of hypoxic-ischemic injury NMDAR subunits 2A and 2B in the SVZ of neonatal rats. Expression of these and other proteins of interest was performed using immunohistochemistry. The results showed that NR2A expression was decreased at 6 h after hypoxic-ischemic injury. By contrast, a significant increase in NR2B expression was observed at 24 h after hypoxic-ischemic injury, induced by the clamping of the right common carotid artery. The functional effect of NMDAR subunits on neurogenesis was also examined by quantifying Nestin and doublecortin (DCX), the microtubule-associated protein expressed only in immature neurons. In addition, the effects of selective non-competitive NMDAR antagonist MK-801 (0.5 mg/kg), NR2B antagonist Ro25-6981 (5 mg/kg), and NR2A antagonist NVP-AAM077 (5 mg/kg) administered 30 min prior to the hypoxic-ischemic injury were examined. The number of Nestin- and DCX-positive cells increased significantly 48 h after hypoxic-ischemic injury, which was reverted by the MK-801 and Ro25-6981 antagonists. Notably, NVP-AAM077 had no significant effect on the expression of Nestin and DCX. In conclusion, the results of the present study demonstrate that hypoxia-ischemia inhibited the expression of NR2A, but promoted the expression of NR2B. Furthermore, NMDAR promoted neurogenesis in the SVZ of neonatal brains.

Effects of NMDA-Receptor Antagonist on the Expressions of Bcl-2 and Bax in the Subventricular Zone of Neonatal Rats with Hypoxia-Ischemia Brain Damage.

Neonatal hypoxia-ischemia brain damage is an important cause of death by affecting prognosis of neural diseases. It is difficult to find effective methods of prevention and treatment due to the complexity of its pathogenesis. N-methyl-D-aspartate (NMDA), as an excitotoxicity amino acids, has proven to play an important role in hypoxic-ischemic. However, the exact effects of the NMDA subunits, NR2A and NR2B, during hypoxic-ischemic have not been investigated in detail. Therefore, we sought to study whether the NMDA receptor antagonist could confer neuroprotective effects in a neonatal rat hypoxia-ischemia model. The effects of intraperitoneal injections of different drugs, namely MK-801 (0.5mg/kg), NVP-AAM077 (5mg/kg), and Ro25-6981 (5mg/kg), on the expressions of anti-apoptotic protein Bcl-2 and apoptosis protein Bax in the subventricular zone were analyzed by immunohistochemical staining to explore the roles of NMDA subunits (NR2A and NR2B) in hypoxic-ischemic. We found that the NR2B antagonist (Ro25-6981) could inhibit hypoxic-ischemic with the increasing Bcl-2 expression. NR2A antagonists (NVP-AAM077) can increase cerebral hypoxia-ischemia in neonatal rats, promoting the expression of apoptotic protein Bax.

Ketamine Interferes with the Proliferation and Differentiation of Neural Stem Cells in the Subventricular Zone of Neonatal Rats

Background: Previous studies have shown ketamine can alter the proliferation and differentiation of neural stem cells (NSCs) in vitro. However, these effects have not been entirely clarified in vivo in the subventricular zone (SVZ) of neonatal rats. The present study was designed to investigate the effects of ketamine on the proliferation and differentiation of NSCs in the SVZ of neonatal rats in vivo. Methods: Postnatal day 7 (PND-7) male Sprague-Dawley rats were administered four injections of 40 mg/kg ketamine at 1-h intervals, and then 5-bromodeoxyuridine (BrdU) was injected intraperitoneally at PND-7, 9 and 13. NSC proliferation was assessed with Nestin/BrdU double-labeling immunostaining. Neuronal and astrocytic differentiation was evaluated with β-tubulin III/BrdU and GFAP/BrdU double-labeling immunostaining, respectively. The expressions of nestin, β-tubulin III and GFAP were measured using Western blot analysis. The apoptosis of NSCs and astrocytes in the SVZ of neonatal rats was evaluated using nestin/caspase-3 and GFAP/caspase-3 double-labeling immunostaining. Results: Neonatal ketamine exposure significantly reduced the number of nestin/BrdU and GFAP/BrdU double-positive cells in the SVZ. Meanwhile, the expressions of nestin and GFAP in the SVZ from the ketamine group were significantly decreased compared those in the control group. Still, no double-positive cells for nestin/caspase-3 and GFAP/caspase-3 were found after ketamine exposure. In addition, the neuronal differentiation of NSCs in the SVZ was markedly promoted by ketamine with an increased number of β-tubulin III/BrdU double-positive cells and enhanced expression of β-tubulin III. These effects of ketamine on the NSCs in the SVZ often lasted at least 1 week after ketamine anesthesia. Conclusion: In the present study, it was demonstrated that ketamine could alter neurogenesis by inhibiting the proliferation of NSCs, suppressing their differentiation into astrocytes and promoting the neuronal differentiation of the NSCs in the SVZ of neonatal rats during a critical period of their neurodevelopment.

Gypenosides protected the neural stem cells in the subventricular zone of neonatal rats that were prenatally exposed to ethanol.

Fetal alcohol spectrum disorder (FASD) can cause severe mental retardation in children who are prenatally exposed to ethanol. The effects of prenatal and early postnatal ethanol exposure on adult hippocampal neurogenesis have been investigated; however, the effects of prenatal ethanol exposure on the subventricular zone (SVZ) have not. Gypenosides (GPs) have been reported to have neuroprotective effects in addition to other bioactivities. The effects of GPs on neural stem cells (NSCs) in the FASD model are unknown. Here, we test the effect of prenatal ethanol exposure on the neonatal SVZ, and the protection potential of GPs on NSCs in FASD rats. Our results show that prenatal ethanol exposure can suppress the cell proliferation and differentiation of neural stem cells in the neonatal SVZ and that GPs (400 mg/kg/day) can significantly increase the cell proliferation and differentiation of neural stem cells inhibited by ethanol. Our data indicate that GPs have neuroprotective effects on the NSCs and can enhance the neurogenesis inhibited by ethanol within the SVZ of neonatal rats. These findings provide new evidence for a potential therapy involving GPs for the treatment of FASD.

Hyperbaric oxygen treatment promotes neural stem cell proliferation in the subventricular zone of neonatal rats with hypoxic-ischemic brain damage.

Hyperbaric oxygen therapy for the treatment of neonatal hypoxic-ischemic brain damage has been used clinically for many years, but its effectiveness remains controversial. In addition, the mechanism of this potential neuroprotective effect remains unclear. This study aimed to investigate the influence of hyperbaric oxygen on the proliferation of neural stem cells in the subventricular zone of neonatal Sprague-Dawley rats (7 days old) subjected to hypoxic-ischemic brain damage. Six hours after modeling, rats were treated with hyperbaric oxygen once daily for 7 days. Immunohistochemistry revealed that the number of 5-bromo-2’-deoxyuridine positive and nestin positive cells in the subventricular zone of neonatal rats increased at day 3 after hypoxic-ischemic brain damage and peaked at day 5. After hyperbaric oxygen treatment, the number of 5-bromo-2’-deoxyuridine positive and nestin positive cells began to increase at day 1, and was significantly higher than that in normal rats and model rats until day 21. Hematoxylin-eosin staining showed that hyperbaric oxygen treatment could attenuate pathological changes to brain tissue in neonatal rats, and reduce the number of degenerating and necrotic nerve cells. Our experimental findings indicate that hyperbaric oxygen treatment enhances the proliferation of neural stem cells in the subventricular zone of neonatal rats with hypoxic-ischemic brain damage, and has therapeutic potential for promoting neurological recovery following brain injury.

Lithium Suppresses Astrogliogenesis by Neural Stem and Progenitor Cells by Inhibiting STAT3 Pathway Independently of Glycogen Synthase Kinase 3 Beta

Transplanted neural stem and progenitor cells (NSCs) produce mostly astrocytes in injured spinal cords. Lithium stimulates neurogenesis by inhibiting GSK3b (glycogen synthetase kinase 3-beta) and increasing WNT/beta catenin. Lithium suppresses astrogliogenesis but the mechanisms were unclear. We cultured NSCs from subventricular zone of neonatal rats and showed that lithium reduced NSC production of astrocytes as well as proliferation of glia restricted progenitor (GRP) cells. Lithium strongly inhibited STAT3 (signal transducer and activator of transcription 3) activation, a messenger system known to promote astrogliogenesis and cancer. Lithium abolished STAT3 activation and astrogliogenesis induced by a STAT3 agonist AICAR (5-aminoimidazole-4-carboxamide 1-beta-D-ribofuranoside), suggesting that lithium suppresses astrogliogenesis by inhibiting STAT3. GSK3β inhibition either by a specific GSK3β inhibitor SB216763 or overexpression of GID5-6 (GSK3β Interaction Domain aa380 to 404) did not suppress astrogliogenesis and GRP proliferation. GSK3β inhibition also did not suppress STAT3 activation. Together, these results indicate that lithium inhibits astrogliogenesis through non-GSK3β-mediated inhibition of STAT. Lithium may increase efficacy of NSC transplants by increasing neurogenesis and reducing astrogliogenesis. Our results also may explain the strong safety record of lithium treatment of manic depression. Millions of people take high-dose (>1 gram/day) lithium carbonate for a lifetime. GSK3b inhibition increases WNT/beta catenin, associated with colon and other cancers. STAT3 inhibition may reduce risk for cancer.

Effects of basic fibroblast growth factor on mRNA expression of transforming growth factor-β1 and its receptor in neonatal rats after brain ischemia

Objective To address the neuroprotective mechanism of basic fibroblast growth factor(bFGF)on ischemic brain injury in neonatal rats.Methods Sixty-six brain ischemia models of 3-day-old Sprague-Dawley rats were made by occluding bilateral common carotid artery.The models were randomly divided into two groups:trial group and control group with 33 rats in each group.The rats of trial group were administrated bFGF 5μg/d through intraperitoneal injection,3 days consecutively.The other thirty-three rats were taken into the sham operation group.The number of gtial fibrillary acidic protein(GFAP)positive cells in the subventricular zone of rata'brain was observed with immunofluorescence assays at the 4th,7th and 14th days after the operation.The mRNA expression of transforming growth factor-β1(TGF-β1)and its receptor Smad2 in the subventricular zone were examined by real-time PCR assays at the above mentioned time points respectively.Results (1)The number of GFAP positive cells in the subventricular zone of the sham operation group was highest at the 7th day(325.4±52.5),and it reached peak at the 14th day in the control group(533.5±75.7)and the trial group(727.2±104.5),there was a significant difference in three groups at each time point(P＜0.01).(2)TGF-β1 and Smad2 mRNA expression peaked at the 7th dayin control group(7.67±1.22,6.22±1.92,respectively),and it reached peak at the 14th day in the trial group(8.65±1.02,7.67±1.41,respectively),there was a significant difference in three groups at each time point(P＜0.01).Conchtsions Exogenous bFlGF could increase the number of astrocytes by inducing the expression of TGF-81 in the subventricular zone of neonatal rats after brain ischemia. Key words: Fibroblast growth factor 2; Brain ischemia; Transforming growth factor beta; As-trocytes; Rats