Minmin Ma

Intranasal delivery of transforming growth factor-beta1 in mice after stroke reduces infarct volume and increases neurogenesis in the subventricular zone

BackgroundThe effect of neurotrophic factors in enhancing stroke-induced neurogenesis in the adult subventricular zone (SVZ) is limited by their poor blood-brain barrier (BBB) permeability.Intranasal administration is a noninvasive and valid method for delivery of neuropeptides into the brain, to bypass the BBB. We investigated the effect of treatment with intranasal transforming growth factor-β1 (TGF-β1) on neurogenesis in the adult mouse SVZ following focal ischemia. The modified Neurological Severity Scores (NSS) test was used to evaluate neurological function, and infarct volumes were determined from hematoxylin-stained sections. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) labeling was performed at 7 days after middle cerebral artery occlusion (MCAO). Immunohistochemistry was used to detect bromodeoxyuridine (BrdU) and neuron- or glia-specific markers for identifying neurogenesis in the SVZ at 7, 14, 21, 28 days after MCAO.ResultsIntranasal treatment of TGF-β1 shows significant improvement in neurological function and reduction of infarct volume compared with control animals. TGF-β1 treated mice had significantly less TUNEL-positive cells in the ipsilateral striatum than that in control groups. The number of BrdU-incorporated cells in the SVZ and striatum was significantly increased in the TGF-β1 treated group compared with control animals at each time point. In addition, numbers of BrdU- labeled cells coexpressed with the migrating neuroblast marker doublecortin (DCX) and the mature neuronal marker neuronal nuclei (NeuN) were significantly increased after intranasal delivery of TGF-β1, while only a few BrdU labeled cells co-stained with glial fibrillary acidic protein (GFAP).ConclusionIntranasal administration of TGF-β1 reduces infarct volume, improves functional recovery and enhances neurogenesis in mice after stroke. Intranasal TGF-β1 may have therapeutic potential for cerebrovascular disorders.

Is There a Stroke Belt in China and Why

Background and Purpose— In 1960s, a stroke belt with high stroke mortality was discovered in the southeast United States. In China, where stroke is the leading cause of death, we aimed to determine whether a focal region of high stroke incidence (stroke belt) exits and, if so, the possible causal and modifiable factors. Methods— We systematically reviewed all studies of stroke incidence in China between 1980 and 2010, and included those which met our criteria for a high-quality study. Criteria for a provincial region of high stroke incidence were ranking in the top one third of all provinces for stroke incidence and ranking of more than one third of prefectural regions within the province in the top two sevenths of all prefectural regions for stroke incidence. We also reviewed regional distribution of major vascular risk factors, socioeconomic status, and demographic profiles in China. Results— Nine eligible studies provided data on the incidence of stroke in 32 of 34 provincial regions of China (with Hong Kong and Macao as exceptions) and 52% of the 347 prefectural regions. Nine provincial regions (Heilongjiang, Tibet, Jilin, Liaoning, Xinjiang, Hebei, Inner Mongolia, Beijing, and Ningxia) met our criteria for a region of high stroke incidence and constitute a stroke belt in north and west China. The incidence of stroke in the stroke belt was 236.2 per 100 000 population compared with 109.7 in regions outside the belt (rate ratio, 2.16; 95% confidence interval, 2.10–2.22). The mean population prevalence of hypertension and overweight (body mass index, >25) was greater in the stroke belt than that in other regions (15.3% versus 10.3%, P<0.001; 21.1% versus 12.3%, P=0.013, respectively). The prevalence of hypertension and overweight also correlated significantly with regional stroke incidence (R=0.642, P<0.001; R=0.438, P=0.014, respectively, by Spearman rank correlation). Conclusions— A stroke belt of high stroke incidence exists in 9 provincial regions of north and west China. The stroke belt may be caused, at least in part, by a higher population prevalence of hypertension and excess body weight. Lowering blood pressure and body weight in the stroke belt may reduce the geographic disparity in stroke risk and incidence in China.

Intranasally delivered bFGF enhances neurogenesis in adult rats following cerebral ischemia

Basic fibroblast growth factor (bFGF) is a very important mitogenic factor with proved neurogenesis effects in the central nervous system. Intranasal administration can bypass blood-brain barrier and deliver drugs into the brain directly. We investigated whether intranasal administration of bFGF at later time points after ischemia could promote adult neurogenesis and improve neurologic functions. Rats received bFGF or saline intranasally once daily for 6 consecutive days, starting at 1 day after transient middle cerebral artery occlusion (MCAO). Bromodeoxyuridine (BrdU) was injected at 5 and 6 days after MCAO. Rats were killed at 7 or 28 days after MCAO. Neurogenesis was assessed by immunostaining for BrdU and cell type-specific markers. Neurological functions were evaluated by the modified Neurological Severity Scores. Compared with the control animals, intranasal administration of bFGF improved behavioral recovery without affecting infarct size, and enhanced proliferation of progenitor cells in the subventricular zone and the subgranular zone of the dentate gyrus (DG). Furthermore, the new proliferated cells could differentiate into neurons (BrdU+NeuN+ cells) in the striatum and DG at 28 days after MCAO. Intranasal administration of bFGF offers a non-invasive alternative for the treatment of stroke.

Decreased serum brain-derived neurotrophic factor (BDNF) is associated with post-stroke depression but not with BDNF gene Val66Met polymorphism.

Abstract Background: Decreased brain-derived neurotrophic factor (BDNF) has been demonstrated in animal models and patients with depression. However, little is known about changes in BDNF in post-stroke depression (PSD). This study investigated the changes in serum BDNF in patients with PSD, and evaluated whether serum concentrations of BDNF were associated with BDNF gene Val66Met polymorphism. Methods: PSD patients were diagnosed in accordance with DSM-IV criteria, and the severity of depression was evaluated with the Hamilton Rating Scale for depression. Serum BDNF was measured twice, first at 7 days after the onset of stroke and then at 3–6 months after stroke. Val66Met polymorphisms of the BDNF gene were determined using the polymerase chain reaction-restriction fragment length polymorphism method. BDNF concentrations and Val66Met polymorphisms were also measured in 30 healthly controls. Results: A total of 93 patients admitted as a result of first time acute ischemic stroke were included. During the 6-month follow-up, 35 patients (37.6%) were diagnosed with PSD. Serum BDNF concentrations were decreased in PSD patients at 3–6 months after stroke (p<0.05). The serum BDNF concentrations were not associated with BDNF gene Val66Met polymorphisms in either patients or healthy controls. Conclusions: Serum concentrations of BDNF decrease in PSD patients and BDNF may play an important role in the pathogenesis of PSD. However, Val66Met polymorphisms are not associated with serum concentrations of BDNF. The mechanism of decreased serum BDNF requires further study.

Intranasal nerve growth factor enhances striatal neurogenesis in adult rats with focal cerebral ischemia

Nerve growth factor (NGF) has been proved with the potential of promoting neurogenesis in adult mammalians. This study was aimed to investigate the effect of intranasal (IN) NGF on striatal neurogenesis and functional recovery in adult rats with focal cerebral ischemia. Rats were subjected to middle cerebral artery occlusion (MCAO) for 2 h, and then reperfused. NGF or vehicle was intranasally administered 24 h after cerebral reperfusion, and the treatments continued for 6 consecutive days there after. All animals were injected with 5-bromodeoxyuridine (BrdU) twice daily for 5–7 days after MCAO, and sacrificed 1 day and 28 days, respectively, after the last BrdU injection. Neural cell proliferation and survival in different brain regions were analyzed. Functional tests and immunohistochemical staining were also performed. The results showed that treatment with IN NGF failed to increase cell proliferation but improved survival of newly generated cells in ipsilateral striatum and subventricular zones (SVZ). Double immunofluorescence with BrdU and neuronal nuclei protein, a mature neuronal marker, were increased in striatum and SVZ in rats treated with IN NGF. The functional recovery was also observed at time of neurogenesis enhancement in striate. In conclusion, IN NGF may enhance neurogenesis and survival of newly generated cells, which may result in improved functional recovery after cerebral ischemia.

Intranasal bFGF-induced progenitor cell proliferation and neuroprotection after transient focal cerebral ischemia.

Basic fibroblast growth factor (bFGF) is a neurotrophic and vasoactive factor, and has therapeutic potential for some central nervous system (CNS) disorders. In this study, we used the intranasal pathway to administer bFGF in adult rats, and evaluated its neuroprotective benefits and effects on endogenous neural stem cells. The bFGF levels after intranasal administration in normal rats were determined by western blot. Transient focal ischemia was achieved by occlusion of the right middle cerebral artery for 2 h. bFGF was given intranasally 2 h after reperfusion and daily thereafter on 3 successive days. Dividing progenitor cells were labeled with bromodeoxyuridine (BrdU) on day 3 of reperfusion. Rats were killed the next day after BrdU labeling. bFGF levels were significantly raised in the olfactory bulb (OB) and striatum following intranasal administration. Intranasal bFGF treatment improved neurological function and reduced infarct volume after cerebral ischemia/reperfusion, while no influence was observed on the blood pressure. And the BrdU incorporation was enhanced in the ipsilateral subventricular zone (SVZ) and striatum following intranasal administration of bFGF. These results demonstrated that bFGF can be directly delivered into brain following intranasal administration, and protects against cerebral ischemia/reperfusion. The protective effects may be attributed to the reduction of infarct volume and enhancement of endogenous progenitors in brain. Therefore, intranasal administration of bFGF may provide an alternative treatment for brain ischemia and some other CNS disorders.

Intranasally delivered TGF-β1 enters brain and regulates gene expressions of its receptors in rats

This study is aimed to evaluate the brain distribution of transforming growth factor-beta1 (TGF-beta1) following intranasal administration and the subsequent biological effects of TGF-beta1. Adult rats were given recombinant human TGF-beta1 (rhTGF-beta1) or vehicle solution intranasally. TGF-beta1 concentrations were significantly raised in several brain regions and the trigeminal nerve following intranasal delivery. The elevation appeared within 30 min and was sustained for at least 6 h, reaching its greatest level at 60 min. A concentration gradient in the central nervous system (CNS) regions was produced during the first 2 h after intranasal administration, with the OB presenting a significantly higher concentration than any other CNS regions. The nasally administered TGF-beta1 subsequently regulated gene expressions of its two receptors (TGF-beta receptor types I and II) in vivo, but did not affect mRNA level of TGF-beta1 itself. Our results suggest that TGF-beta1 can be transported into the CNS via the olfactory and trigeminal pathways, and may consequently exert its biological effects by regulating gene expressions of its receptors. Intranasal administration of neurotrophic factors may offer a potential strategy for treating some CNS disorders.

Combination therapy with intranasal NGF and electroacupuncture enhanced cell proliferation and survival in rats after stroke

Abstract Objective: This work was designed to investigate the effects of the combination therapy with intranasal (IN) administration of nerve growth factor (NGF) and electroacupuncture (EA) on neural progenitors and neurological functional recovery in adult rats after focal ischemia. Methods: Rats subjected to 2 hours of middle cerebral artery occlusion (MCAO) were randomly assigned to four groups: Group 1, IN administration of phosphate-buffered saline (PBS) for control; Group 2, IN administration of NGF alone; Group 3, EA with IN administration of PBS; Group 4, IN administration of NGF with EA. Treatments were initiated at 2 hours after MCAO and continued for three consecutive days. All animals received daily injections of 5-bromodeoxyuridine (BrdU) intraperitoneally for 7 days starting at 24 hours after reperfusion and were killed at 2 hours or 21 days after the last BrdU injection. Neurological function and infarct volume were evaluated. Immunohistochemistry for BrdU was performed to identify newborn cells in the ipsilateral subventricular zone and striatum. Results: The combination treatment led to significant improvement in neurological function and reduction in infarct volume. Cell proliferation and survival of progenitors were enhanced in rats treated with the combination treatment. Conclusion: These results suggest that IN administration of NGF and EA may have a synergistic effect in preventing ischemic injury and enhancing functional recovery after focal cerebral ischemia, which may be attributed to enhanced cell proliferation and survival.

Down-regulation of IGF-1/IGF-1R in hippocampus of rats with vascular dementia

Insulin-like growth factor-1 (IGF-1) has been demonstrated to have neuroprotective effects, but little is known concerning its role in vascular dementia (VaD). This study aimed to evaluate expression of IGF-1 signaling in hippocampus in rat model of VaD, and probe the underlying mechanisms. Permanent occlusion of bilateral common carotid arteries (2-VO) was used as VaD model. Learning and memory functions were declined significantly in 2-VO rats, and these impairments were further deteriorated with the prolongation of 2-VO treatment. IGF-1, IGF-1 receptor (IGF-1R), total Akt and phosphorylated Akt (p-Akt) were all measured at 1, 2 and 4 months following 2-VO injury. Compared with controls, IGF-1, IGF-1 mRNA and p-Akt expression were significantly decreased in hippocampus of 2-VO rats. However, changes of IGF-1R and total Akt levels were not significant. These results suggest that down-regulation of IGF-1 and p-Akt may contribute to the impairments of learning and memory functions after 2-VO. IGF-1/IGF-1R signaling system may involved in the onset and development of VaD.

Intranasal nerve growth factor attenuates tau phosphorylation in brain after traumatic brain injury in rats.

Traumatic brain injury (TBI) is a considerable cause of mild cognitive impairment and dementia. Intranasal administration of nerve growth factor (NGF) has previously been found to improve cognitive function after TBI, but the mechanism remains unclear. This study aimed to investigate the effects of intranasal NGF on the tau hyperphosphorylation following TBI. A modified Feeneys weight-drop model was used to induce TBI. Rats were randomly divided into control group, TBI group, TBI+NGF group, TBI+PDTC group and TBI+IL-1ra group. Rats in TBI+NGF group were administered with NGF (5 μg/d) for 3d before surgery. Hyperphosphorylated tau protein was remarkable in the peri-contusional cortex area with TBI. Both western blotting and immunostaining results displayed intranasal pretreatment of NGF significantly reduced tau phosphorylation. To evaluate the underlying mechanism, the levels of glycogen synthase kinase 3β (GSK-3β), interleukin-1β (IL-1β), and the DNA binding activity of nuclear factor-κB (NF-κB) were assayed. NGF markedly inhibited GSK-3β. NGF also reduced TBI-induced elevation of IL-1β and NF-κB DNA binding activity. Furthermore, PDTC and IL-1ra were injected to prove a potential signaling pathway among NF-κB, IL-1β and GSK-3β. Taken together, these findings demonstrated that intranasal NGF could effectively attenuate the hyperphosphorylation of tau after TBI, which might involve an integrated signaling pathway related to NF-κB.