Fimbria-fornix Transection Research Articles

CircRNA Acbd6 promotes neural stem cell differentiation into cholinergic neurons via the miR-320-5p-Osbpl2 axis

Neural stem cells (NSCs) persist in the dentate gyrus of the hippocampus into adulthood and are essential for both neurogenesis and neural circuit integration. Exosomes have also been shown to play vital roles in regulating biological processes of receptor cells as a medium for cell-to-cell communication signaling molecules. The precise molecular mechanisms of exosome-mediated signaling, however, remain largely unknown. Here, we found that exosomes produced by denervated hippocampi following fimbria–fornix transection could promote the differentiation of hippocampal neural precursor cells into cholinergic neurons in coculture with NSCs. Furthermore, we found that 14 circular RNAs (circRNAs) were upregulated in hippocampal exosomes after fimbria–fornix transection using high-throughput RNA-Seq technology. We further characterized the function and mechanism by which the upregulated circRNA Acbd6 (acyl-CoA-binding domain–containing 6) promoted the differentiation of NSCs into cholinergic neurons using RT–quantitative PCR, Western blot, ELISA, flow cytometry, immunohistochemistry, and immunofluorescence assay. By luciferase reporter assay, we demonstrated that circAcbd6 functioned as an endogenous miR-320-5p sponge to inhibit miR-320-5p activity, resulting in increased oxysterol-binding protein–related protein 2 expression with subsequent facilitation of NSC differentiation. Taken together, our results suggest that circAcbd6 promotes differentiation of NSCs into cholinergic neurons via miR-320-5p/oxysterol-binding protein–related protein 2 axis, which contribute important insights to our understanding of how circRNAs regulate neurogenesis.

Icariin Promotes Survival, Proliferation, and Differentiation of Neural Stem Cells In Vitro and in a Rat Model of Alzheimer's Disease.

Alzheimer's disease (AD) involves the degeneration of cholinergic neurons in the basal forebrain. Neural stem cell (NSC) transplantation has emerged as a promising therapeutic approach for treating AD. Icariin (ICA) is the main active component in Epimedium, a traditional Chinese herb. The purpose of the present study was to investigate the effects and mechanisms of ICA on the proliferation and differentiation of NSCs in the basal forebrain of a fimbria-fornix transection (FFT) rat model. In the present study, ICA promoted the survival, proliferation, and migration of NSCs in vitro. In FFT rats, ICA promoted the proliferation and differentiation of NSCs into neurons and increased the number of cholinergic neurons in the MS and VDB of the basal forebrain. These results suggest that combination therapy of ICA oral administration and NSC transplantation may provide a new potential and effective approach for AD therapy.

Expression and function of Ndel1 during the differentiation of neural stem cells induced by hippocampal exosomesticle

BackgroundIn the brain of adult mammals, neural stem cells persist in the subventricular zone of the lateral ventricle and the subgranular zone of the dentate gyrus, which are specialized niches with proliferative capacity. Most neural stem cells are in a quiescent state, but in response to extrinsic stimuli, they can exit from quiescence and become reactivated to produce new neurons, so neural stem cells are considered to be a potential source for cell replacement therapy of many nervous system diseases. We characterized the expression of Ndel1 during the differentiation of neural stem cells induced by hippocampus exosomes, and assessed the effect of Ndel1 on neural stem cells differentiation.MethodsHippocampal exosomes were isolated and extracted, and co-cultured exosomes with neural stem cells. Western blot, flow cytometry, and immunofluorescence analyses were used to analyze expression of neuronal markers. Further, utilizing high-throughput RNA sequencing technology, we found that nudE neurodevelopment protein 1-like 1 was significantly upregulated in exosomes derived from denervated hippocampus, and then characterized its mechanism and function during neural stem cells differentiation by qRT-PCR, western blot, flow cytometry, and immunofluorescence analyses.ResultsOur results revealed that exosomes of denervated hippocampus promoted the differentiation of neural stem cells into neuron. Hence, we identified that nudE neurodevelopment protein 1-like 1 was significantly upregulated and highly expressed in the nervous system. In addition, we found that miR-107-3p may regulate neural stem cell differentiation by targeting Ndel1.ConclusionsOur results revealed that deafferentation of the hippocampal exosomes co-cultured with neural stem cells could promote them to differentiate into neurons. Hence, we found that miR-107-3p may regulate neural stem cells differentiation by targeting Ndel1. Importantly, Ndel1 enhanced spatial learning and hippocampal neurogenesis in rats after fimbria fornix transection in vivo. These findings set the stage for a better understanding of neurogenesis, a process that 1 day may inspire new treatments for central nervous system diseases.

The role of hippocampal niche exosomes in rat hippocampal neurogenesis after fimbria–fornix transection

Exosomes transfer signaling molecules such as proteins, lipids, and RNAs to facilitate cell–cell communication and play an important role in the stem cell microenvironment. In previous work, we demonstrated that rat fimbria–fornix transection (FFT) enhances neurogenesis from neural stem cells (NSCs) in the subgranular zone (SGZ). However, how neurogenesis is modulated after denervation remains unknown. Here, we investigated whether exosomes in a denervated hippocampal niche may affect neurogenesis. Using the FFT rat model, we extracted hippocampal exosomes and identified them using western blots, transmission electron microscopy (TEM), and nanoparticle size measurement. We also used RNA sequencing and bioinformatic analysis of exosomes to identify noncoding RNA expression profiles and neurogenesis-related miRNAs, respectively. RNA sequencing analysis demonstrated 9 upregulated and 15 downregulated miRNAs. miR-3559-3P and miR-6324 increased gradually after FFT. Thus, we investigated the function of miR-3559-3P and miR-6324 with NSC proliferation and differentiation assays. Transfection of miR-3559-3p and miR-6324 mimics inhibited the proliferation of NSCs and promoted the differentiation of NSCs into neurons, while miR-3559-3p and miR-6324 inhibitors promoted NSC proliferation and inhibited neuronal differentiation. Additionally, the exosome marker molecules CD9, CD63, and Alix were expressed in exosomes extracted from the hippocampal niche. Finally, TEM showed that exosomes were ∼100 nm in diameter and had a “saucer-like” bilayer membrane structure. Taken together, these findings suggest that differentially expressed exosomes and their related miRNAs in the denervated hippocampal niche can promote differentiation of NSCs into neurons.

Effects of the dimeric PSD-95 inhibitor UCCB01-144 on functional recovery after fimbria-fornix transection in rats

Pharmacological inhibition of PSD-95 is a promising therapeutic strategy in the treatment of stroke, and positive effects of monomeric and dimeric PSD-95 inhibitors have been reported in numerous studies. However, whether therapeutic effects will generalize to other types of acute brain injury such as traumatic brain injury (TBI), which has pathophysiological mechanisms in common with stroke, is currently uncertain. We have previously found a lack of neuroprotective effects of dimeric PSD-95 inhibitors in the controlled cortical impact model of TBI in rats. However, as no single animal model is currently able to mimic the complex and heterogeneous pathophysiology of TBI, it is necessary to assess treatment effects across a range of models. In this preliminary study we investigated the neuroprotective abilities of the dimeric PSD-95 inhibitor UCCB01-144 after fimbria-fornix (FF) transection in rats. UCCB01-144 or saline was injected into the lateral tail vein of rats immediately after sham surgery or FF-transection, and effects on spatial delayed alternation in a T-maze were assessed over a 28-day period. Task acquisition was significantly impaired in FF-transected animals, but there were no significant effects of UCCB01-144 on spatial delayed alternation after FF-transection or sham surgery, although decelerated learning curves were seen after treatment with UCCB01-144 in FF-transected animals. The results of the present study are consistent with previous research showing a lack of neuroprotective effects of PSD-95 inhibition in experimental models of TBI.

Exercise-induced improvement in cognitive performance after fimbria-fornix transection depends on the timing of exercise administration.

Exercise after brain injury holds major therapeutic potentials, but it is still uncertain whether such an intervention should take place during the critical time window of intrinsic repair mechanisms. To assess the effects of acute or delayed voluntary exercise in running wheels on post-injury allocentric place learning in an 8-arm radial maze. Forty-eight pre-shaped male rats underwent fimbria-fornix transection (FF) or control surgery (Sham). The animals were divided into six groups: FF group with no access to exercise (FF/NE); FF group starting exercise 1day post-surgery (FF/E+1); FF group starting exercise 8days post-surgery (FF/E+8); FF group starting exercise 21days post-surgery (FF/E+21); Sham group with no access to exercise (Sham/NE), and Sham group starting exercise 1day post-surgery (Sham/E+1). After 7days of exercise 6h/day, all animals underwent 28 place learning acquisition sessions. The FF/E+21 group showed an enhanced acquisition of the task compared to FF/NE. The FF/E+1 and FF/E+8 groups also showed an enhanced task acquisition relative to FF/NE, however with a slower acquisition than the FF/E+21 group. The data underscores the link between exercise and functional recovery after brain injury and emphasizes the importance of optimal timing of this intervention.

Denervated hippocampus provides a favorable microenvironment for neuronal differentiation of endogenous neural stem cells.

Fimbria-fornix transection induces both exogenous and endogenous neural stem cells to differentiate into neurons in the hippocampus. This indicates that the denervated hippocampus provides an environment for neuronal differentiation of neural stem cells. However, the pathways and mechanisms in this process are still unclear. Seven days after fimbria fornix transection, our reverse transcription polymerase chain reaction, western blot assay, and enzyme linked immunosorbent assay results show a significant increase in ciliary neurotrophic factor mRNA and protein expression in the denervated hippocampus. Moreover, neural stem cells derived from hippocampi of fetal (embryonic day 17) Sprague-Dawley rats were treated with ciliary neurotrophic factor for 7 days, with an increased number of microtubule associated protein-2-positive cells and decreased number of glial fibrillary acidic protein-positive cells detected. Our results show that ciliary neurotrophic factor expression is up-regulated in the denervated hippocampus, which may promote neuronal differentiation of neural stem cells in the denervated hippocampus.

Delayed restraint procedure enhances cognitive recovery of spatial function afterfimbria-fornix transection.

To i) evaluate the effect of a restraint procedure (7 days, 2 h/day) on place learning after fimbria-fornix transection (FF), ii) investigate effects of early vs. late administration of restraint, and iii) establish effects of the restraint procedure on expression of brain derived neurotrophic factor (BDNF) in prefrontal cortex and hippocampus. Fifty rats subjected to FF or sham surgery and divided into groups exposed to restraint immediately (early restraint) or 21 days (late restraint) after surgery were trained to acquire an allocentric place learning task. In parallel, 29 animals were subjected to FF or sham surgery and an identical restraint procedure in order to measure concentrations of BDNF and corticosterone. The performance of the sham operated rats was positively affected by the late restraint. In FF-lesioned animals, the late restraint significantly improved task performance compared to the lesioned group with no restraint, while the early restraint was associated with a negative impact on task acquisition. Biochemical analysis after restraint procedure revealed a lesion-induced upregulation of BDNF in FF animals. The improved task performance of lesioned animals suggests a therapeutic effect of this manipulation, independent of BDNF. This effect is sensitive to the temporal administration of treatment.

Equal effects of typical environmental and specific social enrichment on posttraumatic cognitive functioning after fimbria-fornix transection in rats

Enriched environment (EE) has been shown to have beneficial effects on cognitive recovery after brain injury. Typical EE comprises three components: (i) enlarged living area providing physical activation, (ii) sensory stimulation, and (iii) social stimulation. The present study assessed the specific contribution of the social stimulation. Animals were randomly divided into groups of (1) a typical EE, (2) pure social enrichment (SE), or (3) standard housing (SH) and subjected to either a sham operation or transection of the fimbria-fornix (FF). The effect of these conditions on acquisition of a delayed alternation task in a T-maze was assessed. The sham control groups were not affected by housing conditions. In the lesioned groups, both typical EE and SE improved the task acquisition, compared to SH. A baseline one-hour activity measurement confirmed an equal level of physical activity in the EE and SE groups. After delayed alternation testing, pharmacological challenges (muscarinergic antagonist scopolamine and dopaminergic antagonist SKF-83566) were used to assess cholinergic and dopaminergic contributions to task solution. Scopolamine led to a marked impairment in all groups. SKF-83566 significantly enhanced the performance of the lesioned group subjected to SE. The results demonstrate that housing in a typical as well as atypical EE can enhance cognitive recovery after mechanical injury to the hippocampus. The scopolamine challenge revealed a cholinergic dependency during task performance in all groups, regardless of lesion and housing conditions. The dopaminergic challenge revealed a difference in the neural substrates mediating recovery in the lesioned groups exposed to different types of housing.

Stromal derived factor-1α in hippocampus radial glial cells in vitro regulates the migration of neural progenitor cells.

Stromal derived factor-1α (SDF-1α), a critical chemokine that promotes cell homing to target tissues, was presumed to be involved in the traumatic brain injury cortex. In this study, we determined the expression of SDF-1α in the hippocampus after transection of the fimbria fornix (FF). Realtime PCR and ELISA showed that mRNA transcription and SDF-1α proteins increased significantly after FF transection. In vitro, the expression of SDF-1α in radial glial cells (RGCs) incubated with deafferented hippocampus extracts was observed to be greater than in those incubated with normal hippocampus extracts. The co-culture of neural progenitor cells (NPCs) and RGCs indicated that the extracts of deafferented hippocampus induced more NPCs migrating toward RGCs than the normal extracts. Suppression or overexpression of SDF-1α in RGCs markedly either decreased or increased, respectively, the migration of NPCs. These results suggest that after FF transection, SDF-1α in the deafferented hippocampus was upregulated and might play an important role in RGC induction of NPC migration; therefore, SDF-1α is a target for additional research for determining new therapy for brain injuries.

IGF2 Regulates Neuronal Differentiation of Hippocampal Radial Glial Cells In Vitro

We previously observed that radial glial(RG)-like cells showed larger soma, thicker and longer neuritis in vivo(i.e., in rats) after fimbria-fornix (FF) transection, and in vitro RG-like cells showed the same results after the application of the extract from FF-transected hippocampus. In the present study, RG-like cells cultured in 24-well plates supplemented with 5% extract from FF-transected hippocampus were more likely to differentiate into neurons, compared with a normal group. After receiving the insulin-like growth factor 2 (IGF2) gene and knockdown or over expression viruses, the influence of IGF2 on the differentiation of RG-like cells into neurons and the expression of IGF2 were measured. Then, real-time polymerase chain reaction (real-time PCR), enzyme-linked immunosorbent assay (ELISA), and immunofluorescence were used to detect the differentiation of the RG-like cells into neurons. ELISA and real-time PCR showed that the expression of IGF2 in the IGF2 over expression (IGF2 OE) group was significantly higher compared to the normal group. However, the expression of IGF2 in the FF+IGF2 knockdown (FF+IGF2 KD) group was significantly lower than in the FF group. Moreover, the number of MAP2-positive neurons produced in the FF+IGF2 KD group, which expressed less IGF2, was significantly lower compared with the FF group, but the number of MAP2-positive neurons was significantly higher in the IGF2 OE group. The differentiation of RG-like cells into neurons was correlated with a significant increase in the expression of IGF2, indicating that IGF2 was an important regulatory factor for the extract to stimulate the differentiation of RG-like cells into neurons.

Only repeated administration of the serotonergic agonist 8-OH-DPAT improves place learning of rats subjected to fimbria-fornix transection

Serotonergic agonists may act neuroprotectively against brain injury. This study addressed the therapeutic potential of 8-hydroxy-2-di-n-propylamino-tetralin (8-OH-DPAT), a selective 5-HT1A/7 receptor agonist, after mechanical brain injury, and evaluated its effects in terms of acquisition of an allocentric place learning task in a water maze. Rats were divided into 6 experimental groups, three of which were subjected to bilateral transection of fimbria-fornix (FF), while three groups were given control surgery (Sham). After surgery, within both the lesioned, and sham-operated animals, respectively, one group was administered a single dose of saline, one group was given a single dose (0.5mg/kg/b.w.) of 8-OH-DPAT, and one group was treated with daily administration of 8-OH-DPAT (0.5mg/kg/b.w.) for eight days. The acquisition of the water maze based place learning task started on the 8th day post-surgery and continued for 20days. The results show that the lesioned group subjected to repeated administration of 8-OH-DPAT demonstrated a significantly improved acquisition of the place learning task compared to the vehicle injected lesion group. In contrast, the lesioned group treated with a single administration displayed impaired performance compared to the baseline lesion group. There were no significant effects of the 8-OH-DPAT administration in the sham control groups. We conclude that only the repeated stimulation of the 5-HT1A/7 system was associated with beneficial, recovery enhancing effects.

The dynamic expression of Mash1 in the hippocampal subgranular zone after fimbria-fornix transection

Mash1, a member of the basic helix-loop-helix (bHLH) transcription factor family, has previously been considered essential for neuronal differentiation and specification in the nervous system. In this study, we investigated the expression of Mash1 in the hippocampus after fimbria-fornix (FF) transection. Western blot showed that protein of Mash1 increased significantly and peaked at day 7 after FF transection. Immunofluorescence indicated that after FF transection, more newborn cells differentiated into Mash1 positive cells in the deafferented side than that in the normal side, and we investigated that in the neurogenic area, subgranular zone (SGZ), a part of Mash1 positive cells were NeuN positive, and more Mash1/NeuN double positive neurons were identified in the deafferented side than that in the normal side. Additionally, the number of Mash1/NeuN double positive neurons in SGZ increased significantly and peaked at day 7 after FF transection. In vitro, immunofluorescence revealed that extracts of the deafferented hippocampus promoted neuronal differentiation to a greater extent than extracts from normal hippocampus. Deafferented extracts also enhanced Mash1 expression in MAP-2 positive neurons. This study concludes that after FF transection, Mash1 expression in the deafferented hippocampus increased and might play an important role in inducing local progenitors to differentiate into neurons.

Delayed intensive acquisition training alleviates the lesion-induced place learning deficits after fimbria–fornix transection in the rat

This study evaluates the effects of two learning paradigms, intensive vs. baseline, on the posttraumatic acquisition of a water maze based place learning task. Rats were subjected either to a control operation (Sham) or to a fimbria–fornix (FF) transection, which renders the hippocampus dysfunctional and disrupts the acquisition of allocentric place learning. All animals were administered 30 post-lesion acquisition sessions, which spanned either 10 or 30days. The acquisition period was followed by a 7day pause after which a retention probe was administered. The lesioned animals were divided into 3 groups: i) Baseline Acquisition Paradigm (BAP) once daily for 30days starting 1week post-surgery; ii) Early Intensive Acquisition Paradigm (EIAP) 3 times daily for 10days starting 1week post-surgery; and iii) Late Intensive Acquisition Paradigm (LIAP) 3 times daily for 10days starting 3weeks post-surgery. Within the control animals, one group followed the schedule of BAP, and one group followed the schedule of Intensive Acquisition Paradigm (IAP). All lesioned animals showed an impaired task acquisition. LIAP was beneficial in FF animals, in that it led to a better acquisition of the place learning task than the two other acquisition paradigms. The FF/EIAP group did not show improved acquisition compared to the FF/BAP group. The control animals were not differentially affected by the two learning schedules. The findings have implications for cognitive rehabilitation after brain injury and support the assumption that intensive treatment can lead to an improved learning, even when the neural structures underlying such a process are compromised. However, the timing of intensive treatment needs to be considered further.

BMP9 Protects Septal Neurons from Axotomy-Evoked Loss of Cholinergic Phenotype

BackgroundCholinergic projection from the septum to the hippocampus is crucial for normal cognitive function and degeneration of cells and nerve fibers within the septohippocampal pathway contributes to the pathophysiology of Alzheimer's disease. Bone morphogenetic protein (BMP) 9 is a cholinergic differentiating factor during development both in vivo and in vitro.Methodology/Principal FindingsTo determine whether BMP9 could protect the adult cholinergic septohippocampal pathway from axotomy-evoked loss of the cholinergic phenotype, we performed unilateral fimbria-fornix transection in mice and treated them with a continuous intracerebroventricular infusion of BMP9 for six days. The number of choline acetyltransferase (CHAT)-positive cells was reduced by 50% in the medial septal nucleus ipsilateral to the lesion as compared to the intact, contralateral side, and BMP9 infusion prevented this loss in a dose-dependent manner. Moreover, BMP9 prevented most of the decline of hippocampal acetylcholine levels ipsilateral to the lesion, and markedly increased CHAT, choline transporter CHT, NGF receptors p75 (NGFR-p75) and TrkA (NTRK1), and NGF protein content in both the lesioned and unlesioned hippocampi. In addition, BMP9 infusion reduced bilaterally hippocampal levels of basic FGF (FGF2) protein.Conclusions/SignificanceThese data indicate that BMP9 administration can prevent lesion-evoked impairment of the cholinergic septohippocampal neurons in adult mice and, by inducing NGF, establishes a trophic environment for these cells.

Cornel iridoid glycoside improves memory ability and promotes neuronal survival in fimbria–fornix transected rats

Cornel iridoid glycoside (CIG) is a main component extracted from a traditional Chinese herb Cornus officinalis. Our previous study found that CIG improved neurological function in cerebral ischemic rats. The aim of this study was to investigate the therapeutic benefit of CIG in rats with fimbria–fornix transection (FFT) and explore the underlying molecular mechanisms. CIG (20, 60 and 180 mg/kg) or vehicle was intragastrically administered once daily to rats, starting immediately after the surgery and lasting for 4 weeks. Morris water maze and step-through tests showed that the memory deficits seen in FFT rats were significantly improved by CIG treatment. Immunohistochemical analysis showed that CIG treatment attenuated the loss of neurons in hippocampus. To elucidate the memory-improving mechanism of CIG, the neurotrophic factors, synaptic proteins and Bcl-2 family proteins in hippocampus were measured by Western blot analysis. FFT reduced hippocampal protein levels of nerve growth factor (NGF), tyrosine receptor kinase A (Trk A), brain-derived neurotrophic factor (BDNF), synaptophysin (SYP) and B-cell lymphoma-2 (Bcl-2), but not levels of tyrosine receptor kinase B (Trk B) and growth-associated protein 43 (GAP-43). FFT also elevated cytochorome C (Cyt c) and bcl-2-associated X protein (Bax). Administration of CIG to FFT rats significantly elevated the expression of NGF, TrkA, BDNF, SYP, GAP-43 and Bcl-2, and decreased the expression of Cyt c and Bax. These results indicated that CIG effectively counteracted cognitive impairments caused by fimbria–fornix lesions, and the mechanisms might be related to promoting neuronal survival and providing a beneficial environment for brain repair.

Activity‐dependent localization in spines of the F‐actin capping protein CapZ screened in a rat model of dementia

Actin reorganization in dendritic spines is hypothesized to underlie neuronal plasticity. Actin-related proteins, therefore, might serve as useful markers of plastic changes in dendritic spines. Here, we utilized memory deficits induced by fimbria-fornix transection (FFT) in rats as a dementia model to screen candidate memory-associated molecules by using a two-dimensional gel method. Comparison of protein profiles between the transected and control sides of hippocampi after unilateral FFT revealed a reduction in the F-actin capping protein (CapZ) signal on the FFT side. Subsequent immunostaining of brain sections and cultured hippocampal neurons revealed that CapZ localized in dendritic spines and the signal intensity in each spine varied widely. The CapZ content decreased after suppression of neuronal firing by tetrodotoxin treatment in cultured neurons, indicating rapid and activity-dependent regulation of CapZ accumulation in spines. To test input specificity of CapZ accumulation in vivo, we delivered high-frequency stimuli to the medial perforant path unilaterally in awake rats. This path selectively inputs to the middle molecular layer of the dentate gyrus, where CapZ immunoreactivity increased. We conclude that activity-dependent, synapse-specific regulation of CapZ redistribution might be important in both maintenance and remodeling of synaptic connections in neurons receiving specific spatial and temporal patterns of inputs.

Proliferation, Migration, and Neuronal Differentiation of the Endogenous Neural Progenitors in Hippocampus after Fimbria Fornix Transection

ABSTRACTNeurogenesis in the hippocampus continues throughout adult life and can be regulated by the local microenvironment. To determine whether denervation stimulates neurogenesis in hippocampus, proliferation, migration, and differentiation of local neural stem cells (NSCs) in dentate gyrus was investigated after fimbria fornix transection. In the denervated hippocampus, NSCs proliferated markedly and migrated along the subgranular layer, and more newborn cells differentiated into neurons or astrocytes. After denervation, more newborn cells in the deafferented hippocampus expressed Brn-4 and differentiated into β-Tubulin III positive neurons. It is concluded that the local NSCs in hippocampus may proliferate and migrate into granule cell layer, in which changes in the deafferented hippocampus provided a suitable microenvironment for hippocampal neurogenesis and the increased Brn-4 in denervated hippocampus may be involved in this process.

Effects of NT-4 gene modified fibroblasts transplanted into AD rats

It is well known that fibroblasts can act as a cell vector to express functional protein, like neurotrophin-4 (NT-4). The present study evaluated the effect of NT-4 gene modified fibroblasts grafted into the hippocampus of AD rat model. AD rats were reproduced by bilateral transection of the hippocampal fimbria-fornix. The transplanted fibroblasts steadily expressed NT-4 proteins at least 2 months after transplantation. This correlated with a significant rescue in the number of cholinergic neurons in the host hippocampus. Morris water maze tests demonstrated significant improvements in learning and memory, especially in rats receiving NT-4-modified fibroblasts. The present results showed that NT-4 gene modified fibroblasts could provide a long-term and steady expression of NT-4, and it significantly improved the behavior of AD rats. These findings should have important clinical applications in providing a long-term NT-4 Secretion for the treatment of AD.

Therapeutic effects of a restraint procedure on posttraumatic place learning in fimbria-fornix transected rats

Restraint procedures have been shown to influence the neural processes in the brain (dendritic changes or changes in the expression of neurotrophines, etc.) as well as to alter the behavioural performance. While many report deleterious effects of this procedure in normal animals, there are also indications of positive effects in the context of brain injury. In order to address the issue from the perspective of functional posttraumatic recovery, we studied 6 experimental groups of rats—3 groups undergoing a fimbria-fornix transection, and 3 groups remaining neurally intact. Within the lesioned and intact groups, respectively, one group of animals was subjected to an 8-day long restraint procedure (2 h daily) that ended immediately prior to the infliction of trauma; another group was subjected to the same procedure starting immediately after the infliction of trauma; and one group was not subjected to the restraint procedure at all. After a brief period of postoperative pause, the animals were tested on their acquisition of an 8-arm radial maze based place learning task and the effects of the restraint procedure on the task acquisition were evaluated. The results show that within the neurally intact groups, the administration of this procedure had no effect at all. However, the lesioned groups that were subjected to the restraint procedure showed significantly improved acquisition of the studied task compared to the lesioned animals that did not undergo the restraint procedure. The improved task performance suggests a therapeutic effect of this manipulation on the functional recovery after a mechanical trauma.