Two peptidergic drugs increase the synaptophysin immunoreactivity in brains of 24-month-old rats

Synergistic effects of combined therapy with cerebrolysin and enriched environment on anxiety-like behavior and spatial cognitive deficits in posttraumatic stress disorder-like mouse model

Posttraumatic stress disorder (PTSD) is a serious neuropsychiatric disorder that occurs after exposure to stressful, fearful, or troubling events. Cerebrolysin (CBL), consists of low molecular weights neurotrophic factors and amino acids obtained from purified porcine brain proteins. This study aimed to evaluate the possible therapeutic effects of enriched environment (EE) and CBL alone or combined for reducing anxiety and cognitive deficits in PTSD-like mouse models. For this purpose, inescapable electric foot shocks were delivered to Balb/c mice for two consecutive days. Then mice were treated with CBL (2.5 mL/kg) and/or were kept in EE (2 h per day) or received their combination for 14 consecutive days. The hole-board test and Lashley III paradigm were used to assess anxiety and spatial learning and memory, respectively. Changes in the serum corticosterone level and expression of synaptic elements, including; growth-associated protein 43, post-synaptic density 95, and synaptophysin were assessed in the hippocampus. This model caused anxiety and spatial memory impairment associated with increased serum corticosterone levels and decreased synaptic elements. Nevertheless, CBL and/or combination treatment could reverse behavioral and molecular alterations. Our findings indicated that CBL, separately or in combination with EE, is effective in reducing anxiety and spatial memory impairment in PTSD-like mice.

Ryanodine receptors drive neuronal loss and regulate synaptic proteins during epileptogenesis

Status epilepticus (SE) is a clinical emergency that can lead to the development of temporal lobe epilepsy (TLE). The development and maintenance of spontaneous seizures in TLE are linked to calcium (Ca⁺²)-dependent processes such as neuronal cell loss and pathological synaptic plasticity. It has been shown that SE produces an increase in ryanodine receptor-dependent intracellular Ca⁺² levels in hippocampal neurons, which remain elevated during the progression of the disease. However, the participation of ryanodine receptors (RyRs) in the neuronal loss and circuitry rewiring that take place in the hippocampus after SE remains unknown. In this context, we first investigated the functional role of RyRs on the expression of synaptic and plasticity-related proteins during epileptogenesis induced by pilocarpine in Wistar rats. Intrahippocampal injection of dantrolene, a selective pharmacological blocker of RyRs, caused the increase of the presynaptic protein synapsin I (SYN) and synaptophysin (SYP) 48 h after SE induction. Specifically, we observed that SYN and SYP were regulated in hippocampal regions known to receive synaptic inputs, revealing that RyRs could be involved in network changes and/or neuronal protection after SE induction. In order to investigate whether the changes in SYN and SYP were related to neuroplastic changes that could contribute to pathological processes that occur after SE, we evaluated the levels of activity-regulated cytoskeleton-associated protein (ARC) and mossy fiber sprouting in the dentate gyrus (DG). Interestingly, we observed that although SE induced the appearance of intense ARC-positive cells, dantrolene treatment did not change the levels of ARC in both western blot and immunofluorescence analyses. Accordingly, in the same experimental conditions, we were not able to detect changes in the levels of both pre- and post-synaptic plasticity-related proteins, growth associated protein-43 (GAP-43) and postsynaptic density protein-95 (PSD-95), respectively. Additionally, the density of mossy fiber sprouting in the DG was not increased by dantrolene treatment. We next examined the effects of intrahippocampal injection of dantrolene on neurodegeneration. Notably, dantrolene promoted neuroprotective effects by decreasing neuronal cell loss in CA1 and CA3, which explains the increased levels of synaptic proteins, and the apparent lack of positive effect on pathological plasticity. Taken together, our results revealed that RyRs may have a major role in the hippocampal neurodegeneration associated to the development of acquired epilepsy.

Excitotoxicity, neuroinflammation and oxidant stress as molecular bases of epileptogenesis and epilepsy-derived neurodegeneration: The role of vitamin E

Glutamate-mediated excitotoxicity, neuroinflammation, and oxidative stress are common underlying events in neurodegeneration. This pathogenic "triad" characterizes the neurobiology of epilepsy, leading to seizure-induced cell death, increased susceptibility to neuronal synchronization and network alterations. Along with other maladaptive changes, these events pave the way to spontaneous recurrent seizures and progressive degeneration of the interested brain areas. In vivo models of epilepsy are available to explore such epileptogenic mechanisms, also assessing the efficacy of chemoprevention and therapy strategies at the pre-clinical level. The kainic acid model of pharmacological excitotoxicity and epileptogenesis is one of the most investigated mimicking the chronicization profile of temporal lobe epilepsy in humans. Its pathogenic cues include inflammatory and neuronal death pathway activation, mitochondrial disturbances and lipid peroxidation of several regions of the brain, the most vulnerable being the hippocampus. The importance of neuroinflammation and lipid peroxidation as underlying molecular events of brain damage was demonstrated in this model by the possibility to counteract the related maladaptive morphological and functional changes of this organ with vitamin E, the main fat-soluble cellular antioxidant and "conditional" co-factor of enzymatic pathways involved in polyunsaturated lipid metabolism and inflammatory signaling. The present review paper provides an overview of the literature supporting the potential for a timely intervention with vitamin E therapy in clinical management of seizures and epileptogenic processes associated with excitotoxicity, neuroinflammation and lipid peroxidation, i.e. the pathogenic "triad".

Prospective, double blinded, comparative assessment of the pharmacological activity of Cerebrolysin and distinct peptide preparations for the treatment of embolic stroke

BACKGROUND

Our previous work in acute ischemic stroke and TBI models focused on efficacy and pharmacological parameters of Cerebrolysin®. In this prospective, randomized, blinded, placebo-controlled study we compared efficacy of neuropeptide preparations with putative neurotrophic potential to the reference product Cerebrolysin® by assessing functional outcome and lesion volumes after embolic stroke in a rodent model.

METHODS

Male Wistar rats were subjected to embolic right middle cerebral artery occlusion and were treated with: 1) Cognistar® (Cerebroprotein Hydrolysate) 2.5 ml/kg, 2) Cerebrolysat® 2.5 ml/kg, 3) Cortexin® 1.7 mg/kg, 4) Cerebrolysin® 2.5 ml/kg, or 5) 1 ml of saline according to a pre-generated randomization plan. Dosages were defined according to the packet leaflet of the corresponding preparation and were adapted to the animal model as previously described. All enrolled rats received intraperitoneal injections once daily for 10 consecutive days, starting 4 h after occlusion. Functional outcome was assessed once weekly over four weeks by using a battery of behavioral tests. Infarct volume was measured four weeks after occlusion. Generalized Estimation Equations (GEE) was performed to study the treatment effect on overall functional recovery at day 28 (primary outcome), compared to saline controls.

RESULTS

Similar functional outcome was observed for saline control, Cognistar®, Cerebrolysat® and Cortexin®; in contrast, a significantly improved neurological outcome was observed with Cerebrolysin® treatment in comparison to saline as well as to the comparator drug treatment (p < .002). However, there was no significant difference in lesion volumes between rats treated with either Cortexin® (33.5 ± 1.9%), Cerebrolysat® (28.5 ± 2.4%), Cognistar® (34.7 ± 2.0%), or Cerebrolysin® (26.5 ± 2.3%) compared to saline-treated rats (30.8 ± 2.1%).

CONCLUSION

Among all tested neuropeptide preparations, Cerebrolysin® was the only agent that was associated with a significant improvement of neurological outcome after stroke.

Intranasal cerebrolysin improves cognitive function and structural synaptic plasticity in photothrombotic mouse model of medial prefrontal cortex ischemia

Medial prefrontal cortex (mPFC) ischemia affects post-stroke cognitive outcomes. We aimed to investigate the effects of different doses and routes of cerebrolysin (CBL) on the structural synaptic plasticity and cognitive function after mPFC ischemia in mice. Thence, CBL (1, 2.5 ml/kg/i.p./daily) or (1 ml/kg/i.n./daily), were administrated in photothrombotic mouse model of mPFC ischemia for two weeks. Episodic and spatial memories were assessed by the What-Where-Which (WWWhich) and Barnes tasks. Growth-associated protein 43 (GAP-43), postsynaptic density-95 (PSD-95), and synaptophysin (SYN) levels were measured in the lesioned area using western blot analysis. Dendritic arbors, spine densities, and morphology were assessed via Golgi-Cox staining. Treatment with 2.5 ml/kg/i.p. and 1 ml/kg/i.n. doses attenuated mPFC ischemia-induced episodic and spatial memories impairment. Results showed an obvious increase in the GAP-43, PSD-95 and SYN levels and improvement in the structural synaptic indexes in lesioned area induced by the same doses and routes of CBL. In conclusion, we found that specific doses/routes of CBL have positive effects on the structural synaptic plasticity and cognitive outcomes after mPFC ischemia.

Cerebrolysin: a multi-target drug for recovery after stroke

INTRODUCTION

Cerebrolysin is a neuropeptide preparation with neurotrophic effects and promotes recovery after brain injury. Its preclinical profile promises wide applications due to its multi-target effects. Currently, Cerebrolysin is used for treatment of cerebral ischemia and neurodegeneration. Areas covered: In stroke, earlier clinical trials with Cerebrolysin were performed mostly in mildly affected stroke populations, which usually have a favorable prognosis. Due to this selection, a floor or ceiling effect of recovery measures in the mild cases may have prevented to show a clear benefit between treatment groups. In contrast, subgroup analyses of more severely affected patients reveal a strikingly positive effect for enhanced recovery. Based on the findings from several studies, it became evident that the effect size of Cerebrolysin was increasing with stroke severity. Other controlled studies showed that Cerebrolysin can be safely used in combination with thrombolysis. More recently, Cerebrolysin has been tested not only for neuroprotection but also for its neurorecovery potential and also showed efficacy in patients with moderate to severe strokes. Expert commentary: Cerebrolysin shows a benefit mostly in moderate to severe ischemic stroke patients and an overall significant effect for functional recovery when combined with neurorehabilitation versus neurorehabilitation alone. This gives lead to the planning of a more rigorous study design in the future.

Effects of cerebrolysin on nerve growth factor system in the aging rat brain

BACKGROUND

Aging is associated with some cognitive decline and enhanced risk of development of neurodegenerative diseases. It is assumed that altered metabolism and functions of neurotrophin systems may underlie these age-related functional and structural modifications. CerebrolysinTM (CBL) is a neuropeptide mixture with neurotrophic effects, which is widely used for the treatment of stroke and traumatic brain injury patients. It is also evident that CBL has an overall beneficial effect and a favorable benefit-risk ratio in patients with dementia. However, the effects of CBL on cognition and brain neurotrophin system in normal aging remain obscure.

OBJECTIVE

The aim of the present study was to examine the age-related modifications of endogenous neurotrophin systems in the brain of male Wistar rats and the effects of CBL on learning and memory as well as the levels neurotrophins and their receptors.

METHODS

Old (23-24 months) and young (2-3 months) male Wistar rats were used for the study. A half of animals were subjected to CBL course (2.5 ml/kg, 20 i.p. injections). Behavior of rats was studied using the open field test and simple water maze training. The contents of NGF and BDNF were studied using enzyme-linked immunosorbent assay; the expression of neurotrophin receptors was estimated by Western-blot analysis.

RESULTS

CBL treatment did not affect general status, age-related weight changes, general locomotor activity as well as general brain histology. In a water maze task, a minor effect of CBL was observed in old rats at the start of training and no effect on memory retention was found. Aging induced a decrease in neurotrophin receptors TrkA, TrkB, and p75NTR in the neocortex. CBL counteracted effects of aging on neocortical TrkA and p75NTR receptors and decreased expression of proNGF without influencing overall NGF levels. BDNF system was not significantly affected by CBL.

CONCLUSION

The pro-neuroplastic "antiaging" effects of CBL in the neocortex of old animals were generally related to the NGF rather than the BDNF system.

Cerebrolysin combined with rehabilitation promotes motor recovery in patients with severe motor impairment after stroke

BACKGROUND

Cerebrolysin is a neuropeptide preparation with neuroprotective and neurorestorative effects. Combining Cerebrolysin treatment with a standardized rehabilitation program may have a potential synergistic effect in the subacute stage of stroke. This study aims to evaluate whether Cerebrolysin provides additional motor recovery on top of rehabilitation therapy in the subacute stroke patients with moderate to severe motor impairment.

METHODS

This phase IV trial was designed as a prospective, multicenter, randomized, double-blind, placebo-controlled, parallel-group study. A total of 70 patients (Cerebrolysin n = 35, placebo n = 35) with moderate to severe motor function impairment were included within 7 days after stroke onset and were randomized to receive a 21-day treatment course of either Cerebrolysin or placebo, given in addition to standardized rehabilitation therapy. Assessments were performed at baseline, immediately after treatment as well as 2 and 3 months after stroke onset. The plasticity of motor system was assessed by diffusion tensor imaging and with resting state functional magnetic resonance imaging.

RESULTS

Both groups demonstrated significant improvement in motor function (p < 0.05); however, no significant difference was found between the two groups. In the stroke patients with severe motor impairment, the Cerebrolysin group exhibited significantly more improvement in motor function compared with the placebo group (p < 0.05). Effects of Cerebrolysin were demonstrated as restricted increments of corticospinal diffusivity and as recovery of the sensorimotor connectivity.

CONCLUSION

The combination of standard rehabilitation therapy with Cerebrolysin treatment in the subacute stroke has shown additional benefit on motor recovery and plastic changes of the corticospinal tract in patients with severe motor impairment.

TRIAL REGISTRATION

NCT01996761 (November 5, 2013).

Stereological investigation of the age-related changes of the myelinated fibers in the hippocampus of male rats

The decline of hippocampus-dependent learning and memory during normal aging is not associated with neuron death and synapse loss. Until now, age-related changes in the myelinated fibers of the hippocampus have not been investigated. Therefore, in this study, the myelinated fibers in the hippocampi of young (6 months), middle-aged (18 months), and old-aged (28 months) male Sprague-Dawley rats were studied with transmission electron microscope and stereological methods, following spatial learning tests in a Morris water maze. The results showed that hippocampus-dependent spatial learning was impaired in old-aged rats but that the total volume, length, and mean diameter of the myelinated fibers in the hippocampus, as well as the hippocampal volume, remained constant during the normal aging process. Our results suggest that the age-related decline in hippocampus-dependent spatial learning is not attributable to myelinated fiber changes in the hippocampus and that other, undetermined factors are responsible.

Post-seizure α-tocopherol treatment decreases neuroinflammation and neuronal degeneration induced by status epilepticus in rat hippocampus

Vitamin E (as α-tocopherol, α-T) was shown to have beneficial effects in epilepsy, mainly ascribed to its antioxidant properties. Besides radical-induced neurotoxicity, neuroinflammation is also involved in the pathophysiology of epilepsy, since neuroglial activation and cytokine production exacerbate seizure-induced neurotoxicity and contribute to epileptogenesis. We previously showed that α-T oral supplementation before inducing status epilepticus, markedly reduces astrocytic and microglial activation, neuronal cell death and oxidative stress in the hippocampus, as observed 4 days after seizure. In order to evaluate the possibility that such a neuroprotective and anti-inflammatory effect may also provide a strategy for an acute intervention in epilepsy, in this study, seizures were induced by single intaperitoneal injection of kainic acid and, starting from 3 h after status epilepticus, rats were treated with an intraperitoneal bolus of α-T (250 mg/kg b.w.; once a day) for 4 days, that was the time after which morphological and biochemical analyses were performed on hippocampus. Post-seizure α-T administration significantly reduced astrocytosis and microglia activation, and decreased neuron degeneration and spine loss; these effects were associated with the presence of a lowered lipid peroxidation in hippocampus. These results confirm and further emphasize the anti-inflammatory and neuroprotective role of α-T in kainic acid-induced epilepsy. Moreover, the findings show that post-seizure treatment with α-T provides an effective secondary prevention against post-seizure inflammation-induced brain damages and possibly against their epileptogenic effects.

Peptidergic drugs for the treatment of traumatic brain injury

Traumatic brain injury (TBI) is a devastating medical condition that has an enormous socioeconomic impact because it affects more than 10 million people annually worldwide and is associated with high rates of hospitalization, mortality and disability. Although TBI survival has improved continuously for decades, particularly in developing countries, implementation of an effective drug therapy for TBI represents an unmet clinical need. All confirmatory trials conducted to date with drugs targeting a single TBI pathological pathway failed to show clinical efficacy, probably because TBI pathophysiology involves multiple cellular and molecular mechanisms of secondary brain damage. According to current scientific evidence of the participation of peptide-mediated mechanisms in the processes of brain injury and repair after TBI, peptidergic drugs represent a multimodal therapy alternative to improve acute outcome and long-term recovery in TBI patients. Preliminary randomized-controlled clinical trials and open-label studies conducted to date with the peptidergic drug Cerebrolysin® (Ever Neuro Pharma GmbH, Unterach, Austria) and with the endogenous neuropeptides progesterone and erythropoietin, showed positive clinical results. Cerebrolysin-treated patients had a faster clinical recovery, a shorter hospitalization time and a better long-term outcome. Treatment with progesterone showed advantages over placebo regarding TBI mortality and clinical outcome, whereas erythropoietin only reduced mortality. Further validation of these promising findings in confirmatory randomized-controlled clinical trials is warranted. This article reviews the scientific basis and clinical evidence on the development of multimodal peptidergic drugs as a therapeutic option for the effective treatment of TBI patients.

Beneficial effects of a neurotrophic peptidergic mixture persist for a prolonged period following treatment interruption in a transgenic model of Alzheimer's disease

Neurodegenerative disorders such as Alzheimer's disease (AD) are characterized by the loss of neurotrophic factors, and experimental therapeutical approaches to AD have investigated the efficacy of replacing or augmenting neurotrophic factor activity. Cerebrolysin, a peptide mixture with neurotrophic-like effects, has been shown to improve cognition in patients with AD and to reduce synaptic and behavioral deficits in transgenic (tg) mice overexpressing the amyloid precursor protein (APP). However, it is unclear how long-lasting the beneficial effects of Cerebrolysin are and whether or not behavioral and neuropathological alterations will reappear following treatment interruption. The objective of the present study was to investigate the consequences of interrupting Cerebrolysin treatment (washout effect) 3 and 6 months after the completion of a 3-month treatment period in APP tg mice. We demonstrate that, in APP tg mice, Cerebrolysin-induced amelioration of memory deficits in the water maze and reduction of neurodegenerative pathology persist for 3 months after treatment interruption; however, these effects dissipate 6 months following treatment termination. Immunohistochemical analysis demonstrated that the decrease in neocortical and hippocampal amyloid plaque load observed in Cerebrolysin-treated APP tg mice immediately after treatment was no longer apparent at 3 months after treatment interruption, indicating that the beneficial effects of Cerebrolysin at this time point were independent of its effect on amyloid-β deposition. In conclusion, the results demonstrate that the effects of Cerebrolysin persist for a significant period of time following treatment termination and suggest that this prolonged effect may involve the neurotrophic factor-like activity of Cerebrolysin.

Efficacy and safety of Cerebrolysin in moderate to moderately severe Alzheimer's disease: results of a randomized, double-blind, controlled trial investigating three dosages of Cerebrolysin

BACKGROUND

cerebrolysin is a neuropeptide preparation mimicking the effects of neurotrophic factors. This subgroup analysis assessed safety and efficacy of Cerebrolysin in patients with moderate to moderately severe Alzheimer's disease (AD) (ITT data set: N = 133; MMSE: 14-20) included in a dose-finding study (ITT data set: N = 51; MMSE: 14-25). Results of the mild AD subgroup (ITT data set: N = 118; MMSE: 21-25) are also presented.

METHODS

patients with AD received 100 ml IV infusions of Cerebrolysin (10, 30 or 60 ml diluted in saline; N = 32, 34 and 35, respectively) or placebo (saline; N = 32) over twelve weeks (5 days per week for 4 weeks and 2 days per week for another 8 weeks). Primary efficacy criteria ADAS-cog+ (Alzheimer's Disease Assessment Scale Cognitive Subpart Modified) and CIBIC+ (Clinical Interview-based Impression of Change with Caregiver Input) were assessed 24 weeks after baseline.

RESULTS

at week 24, Cerebrolysin improved the global clinical function significantly with all three dosages and induced significant improvements in cognition, initiation of activities of daily living (ADL) and neuropsychiatric symptoms at 10-, 30- and 60-ml doses, respectively. Treatment effects on total ADL and other secondary parameters (MMSE, Trail-making test) were not significant. Cerebrolysin was safe and well tolerated.

CONCLUSIONS

these results demonstrate the efficacy of Cerebrolysin in moderate to moderately severe AD, showing dose-specific effects similar to those reported for patients with mild to moderate AD. The benefits of Cerebrolysin in advanced AD need to be confirmed in larger trials.

Cerebrolysin: a review of its use in dementia

Cerebrolysin is a parenterally administered, porcine brain-derived peptide preparation that has pharmacodynamic properties similar to those of endogenous neurotrophic factors. In several randomized, double-blind trials of up to 28 weeks' duration in patients with Alzheimer's disease, Cerebrolysin was superior to placebo in improving global outcome measures and cognitive ability. A large, randomized comparison of Cerebrolysin, donepezil or combination therapy showed beneficial effects on global measures and cognition for all three treatment groups compared with baseline. Although not as extensively studied in patients with vascular dementia, Cerebrolysin has also shown beneficial effects on global measures and cognition in this patient population. Cerebrolysin was generally well tolerated in clinical trials, with dizziness (or vertigo) being the most frequently reported adverse event. Although further studies with Cerebrolysin, including longer term trials and further exploration of its use in combination with cholinesterase inhibitors, are needed to more clearly determine its place in the management of Alzheimer's disease and vascular dementia, available data suggest that Cerebrolysin is a useful addition to the treatment options available for dementia.

Neurotrophic effects of Cerebrolysin in the Mecp2(308/Y) transgenic model of Rett syndrome

Rett syndrome is a childhood neurodevelopmental disorder caused by mutations in the gene encoding for methyl-CpG-binding protein (MeCP2). Neuropathological studies in patients with Rett syndrome and in MeCP2 mutant models have shown reduced dendritic arborization and abnormal neuronal packing. We have previously shown that Cerebrolysin (CBL), a neurotrophic peptide mixture, ameliorates the synaptic and dendritic pathology in models of aging and neurodegeneration. This study aimed to determine whether CBL was capable of reducing behavioral and neuronal alterations in Mecp2(308/Y) mutant mice. Two sets of experiments were performed, the first with 4-month-old male Mecp2(308/Y) mutant mice treated with CBL or vehicle for 3 months (Group A) and the second with 1-month-old mice treated for 6 months (Group B). Behavioral analysis showed improved motor performance with CBL in Group A and a trend toward improvement in Group B. Consistent with behavioral findings, neuropathological analysis of the basal ganglia showed amelioration of dendritic simplification in CBL-treated Mecp2(308/Y) mutant mice. CBL treatment also ameliorated dendritic pathology and neuronal loss in the hippocampus and neocortex in Mecp2(308/Y) mutant mice. In conclusion, this study demonstrates that CBL promotes recovery of dendritic and neuronal damage and behavioral improvements in young adult Mecp2(308/Y) mutant mice and suggests that CBL may have neurotrophic effects in this model. These findings support the possibility that CBL may have beneficial effects in the management of Rett syndrome.

Reductions in qEEG slowing over 1 year and after treatment with Cerebrolysin in patients with moderate-severe traumatic brain injury

Changes in quantitative EEG (qEEG) recordings over a 1-year period and the effects of Cerebrolysin (Cere) on qEEG slowing and cognitive performance were investigated in postacute moderate-severe traumatic brain injury (TBI) patients. Time-related changes in qEEG activity frequency bands (increases of alpha and beta, and reductions of theta and delta relative power) and in qEEG slowing (reduction of EEG power ratio) were statistically significant in patients with a disease progress of less than 2 years at baseline, but not in those patients having a longer disease progress time. Slowing of qEEG activity was also found to be significantly reduced in TBI patients after 1 month of treatment with Cere and 3 months later. Therefore, Cere seems to accelerate the time-related reduction of qEEG slowing occurring in untreated patients. The decrease of qEEG slowing induced by Cere correlated with the improvement of attention and working memory. Results of this exploratory study suggest that Cere might improve the functional recovery after brain injury and encourage the conduction of further controlled clinical trials.

Effects of Cerebrolysin on neurogenesis in an APP transgenic model of Alzheimer's disease

Cerebrolysin (CBL) is a peptide mixture with neurotrophic effects that might reduce the neurodegenerative alterations in Alzheimer's disease (AD). We have previously shown that in the amyloid precursor protein (APP) transgenic (tg) mouse model of AD, CBL improves synaptic plasticity and behavioral performance. However, the mechanisms are not completely clear. The neuroprotective effects of CBL might be related to its ability to promote neurogenesis in the hippocampal subgranular zone (SGZ) of the dentate gyrus (DG). To study this possibility, tg mice expressing mutant APP under the Thy-1 promoter were injected with BrdU and treated with CBL for 1 and 3 months. Compared to non-tg controls, vehicle-treated APP tg mice showed decreased numbers of BrdU-positive (+) and doublecortin+ (DCX) neural progenitor cells (NPC) in the SGZ. In contrast, APP tg mice treated with CBL showed a significant increase in BrdU+ cells, DCX+ neuroblasts and a decrease in TUNEL+ and activated caspase-3 immunoreactive NPC. CBL did not change the number of proliferating cell nuclear antigen+ (PCNA) NPC or the ratio of BrdU+ cells converting to neurons and astroglia in the SGZ cells in the APP tg mice. Taken together, these studies suggest that CBL might rescue the alterations in neurogenesis in APP tg mice by protecting NPC and decreasing the rate of apoptosis. The improved neurogenesis in the hippocampus of CBL-treated APP tg mice might play an important role in enhancing synaptic formation and memory acquisition.

MAP2 and synaptophysin protein expression following motor learning suggests dynamic regulation and distinct alterations coinciding with synaptogenesis

Learning a new motor skill can induce neuronal plasticity in rats. Within motor cortex, learning-induced plasticity includes dendritic reorganization, synaptogenesis, and changes in synapse morphology. Behavioral studies have demonstrated that learning requires protein synthesis. It is likely that some of the proteins synthesized during learning are involved in, or the result of, learning-induced structural plasticity. We predicted the expression of proteins involved in neural plasticity would be altered in a learning dependent fashion. Long-Evans rats were trained on a series of motor tasks that varied in complexity, so that the effects of activity could be teased apart from the effects of learning. The motor cortices were examined for MAP2 and synaptophysin protein using Western blotting and immunohistochemistry. Western blotting revealed that expression of MAP2 was not detectably influenced by learning, whereas synaptophysin expression increased on day 1, 3, and 5 of complex motor skill learning. Expression of MAP2 does not seem to indicate difficulty of task or duration of training time, whereas increases in synaptophysin expression, which appear diffusely across the cortex, seem to be correlated with the first 5 days of motor skill learning. Similar findings with GAP-43 suggest the change in synaptophysin may coincide with synapse formation. Immunohistochemistry did not reveal any localized changes in protein expression. These data indicate a difference in learning-induced expression in the mammalian brain compared to reports in the literature, which have often focused on stimulation to induce alterations in protein expression.

alpha-Tocopherol affects neuronal plasticity in adult rat dentate gyrus: the possible role of PKCdelta

Hippocampus dentate gyrus (DG) is characterized by neuronal plasticity processes in adulthood, and polysialylation of NCAM promotes neuronal plasticity. In previous investigations we found that alpha-tocopherol increased the PSA-NCAM-positive granule cell number in adult rat DG, suggesting that alpha-tocopherol may enhance neuronal plasticity. To verify this hypothesis, in the present study, structural remodeling in adult rat DG was investigated under alpha-tocopherol supplementation conditions. PSA-NCAM expression was evaluated by Western blotting, evaluation of PSA-NCAM-positive granule cell density, and morphometric analysis of PSA-NCAM-positive processes. In addition, the optical density of synaptophysin immunoreactivity and the synaptic profile density, examined by electron microscopy, were evaluated. Moreover, considering that PSA-NCAM expression has been found to be related to PKCdelta activity and alpha-tocopherol has been shown to inhibit PKC activity in vitro, Western blotting and immunohistochemistry followed by densitometry were used to analyze PKC. Our results demonstrated that an increase in PSA-NCAM expression and optical density of DG molecular layer synaptophysin immunoreactivity occurred in alpha-tocopherol-treated rats. Electron microscopy analysis showed that the increase in synaptophysin expression was related to an increase in synaptic profile density. In addition, Western blotting revealed a decrease in phospho-PKC Pan and phospho-PKCdelta, demonstrating that alpha-tocopherol is also able to inhibit PKC activity in vivo. Likewise, immunoreactivity for the active form of PKCdelta was lower in alpha-tocopherol-treated rats than in controls, while no changes were found in PKCdelta expression. These results demonstrate that alpha-tocopherol is an exogenous factor affecting neuronal plasticity in adult rat DG, possibly through PKCdelta inhibition.

Cerebrolysin decreases amyloid-beta production by regulating amyloid protein precursor maturation in a transgenic model of Alzheimer's disease

Cerebrolysin is a peptide mixture with neurotrophic effects that might reduce the neurodegenerative pathology in Alzheimer's disease (AD). We have previously shown in an amyloid protein precursor (APP) transgenic (tg) mouse model of AD-like neuropathology that Cerebrolysin ameliorates behavioral deficits, is neuroprotective, and decreases amyloid burden; however, the mechanisms involved are not completely clear. Cerebrolysin might reduce amyloid deposition by regulating amyloid-beta (Abeta) degradation or by modulating APP expression, maturation, or processing. To investigate these possibilities, APP tg mice were treated for 6 months with Cerebrolysin and analyzed in the water maze, followed by RNA, immunoblot, and confocal microscopy analysis of full-length (FL) APP and its fragments, beta-secretase (BACE1), and Abeta-degrading enzymes [neprilysin (Nep) and insulin-degrading enzyme (IDE)]. Consistent with previous studies, Cerebrolysin ameliorated the performance deficits in the spatial learning portion of the water maze and reduced the synaptic pathology and amyloid burden in the brains of APP tg mice. These effects were associated with reduced levels of FL APP and APP C-terminal fragments, but levels of BACE1, Notch1, Nep, and IDE were unchanged. In contrast, levels of active cyclin-dependent kinase-5 (CDK5) and glycogen synthase kinase-3beta [GSK-3beta; but not stress-activated protein kinase-1 (SAPK1)], kinases that phosphorylate APP, were reduced. Furthermore, Cerebrolysin reduced the levels of phosphorylated APP and the accumulation of APP in the neuritic processes. Taken together, these results suggest that Cerebrolysin might reduce AD-like pathology in the APP tg mice by regulating APP maturation and transport to sites where Abeta protein is generated. This study clarifies the mechanisms through which Cerebrolysin might reduce Abeta production and deposition in AD and further supports the importance of this compound in the potential treatment of early AD.

A 24-week, double-blind, placebo-controlled study of three dosages of Cerebrolysin in patients with mild to moderate Alzheimer's disease

Cerebrolysin (Cere) is a compound with neurotrophic activity shown to be effective in Alzheimer's disease in earlier trials. The efficacy and safety of three dosages of Cere were investigated in this randomized, double-blind, placebo-controlled, study. Two hundred and seventy-nine patients were enrolled (69 Cere 10 ml; 70 Cere 30 ml; 71 Cere 60 ml and 69 placebo). Patients received iv infusions of 10, 30, 60 ml Cere or placebo 5 days/week for the first 4 weeks and thereafter, two iv infusions per week for 8 weeks. Effects on cognition and clinical global impressions were evaluated 4, 12 and 24 weeks after the beginning of the infusions using the CIBIC+ and the modified Alzheimer's Disease Assessment Scale (ADAS)-cog. At week 24, significant improvement of cognitive performance on the ADAS-cog (P=0.038) and global function (CIBIC+; P>0.001) was observed for the 10 ml dose. The 30 and 60 ml doses showed significant improvement of the global outcome but failed to show significant improvement of cognition. The results are consistent with a reversed U-shaped dose-response relationship for Cere. The percentage of patients reporting adverse events was similar across all study groups. Cere treatment was well tolerated and led to significant, dose-dependent improvement of cognition and global clinical impression.

Blockade of N-methyl-D-aspartate receptors by phencyclidine causes the loss of corticostriatal neurons

Perinatal administration of the N-methyl-Dd-aspartate (NMDA) receptor antagonist phencyclidine (PCP) has been reported to produce regionally selective apoptotic cell death in the frontal cortex. The development of certain behavioral abnormalities following PCP treatment suggested that extracortical regions such as the striatum also could be affected. In this study, perinatal PCP treatment caused a marked reduction in striatal, but not hippocampal, staining for polysialic acid-neural cell adhesion molecule (PSA-NCAM), an NMDA-regulated molecule important in synaptogenesis. In order to isolate striatal influences to the cortex, this investigation was continued in vitro using corticostriatal slices. For these experiments we cultured coronal corticostriatal slices from postnatal day 7 rats. After 4 days in vitro, PCP was added for 48 h and then washed out for 24 h before harvesting the tissue. Similar to what was observed in vivo, we found that PCP treatment results in a marked reduction in striatal staining for PSA-NCAM. No change was observed in the mature form of NCAM. In striatal synaptoneurosomes, immunoblot analysis confirmed that the levels of PSA-NCAM and synaptophysin, a molecule often used as a marker of synaptogenesis, were substantially down-regulated by PCP. These effects were prevented by M40403, a superoxide dismutase mimetic that also prevented the PCP-induced terminal dUTP nick-end labeling of DNA fragments that was observed selectively in the cortex. These data suggest that PCP causes cell death by apoptosis selectively in the cortex, but not in the striatum, following either in vivo treatment of perinatal rat pups or in vitro treatment of corticostriatal slices. Further, cortical apoptosis induced by PCP negatively impacts striatal synaptogenesis, a process important in normal neural development. This deficit is probably caused by a reduction in corticostriatal neurotransmission. It is possible that the dysregulation of striatal synaptogenesis contributes to the behavioral abnormalities observed following perinatal PCP administration in vivo.

Activity-dependent changes in synaptophysin immunoreactivity in hippocampus, piriform cortex, and entorhinal cortex of the rat

Synaptophysin, an integral membrane glycoprotein of synaptic vesicles, has been widely used to investigate synaptogenesis in both animal models and human patients. Kindling is an experimental model of complex partial seizures with secondary generalization, and a useful model for studying activation-induced neural growth in adult systems. Many studies using Timm staining have shown that kindling promotes sprouting in the mossy fiber pathway of the dentate gyrus. In the present study, we used synaptophysin immunohistochemistry to demonstrate activation-induced neural sprouting in non-mossy fiber cortical pathways in the adult rat. We found a significant kindling-induced increase in synaptophysin immunoreactivity in the stratum radiatum of CA1 and stratum lucidum/radiatum of CA3, the hilus, the inner molecular layer of the dentate gyrus, and layer II/III of the piriform cortex, but no significant change in layer II/III of the entorhinal cortex, 4 weeks after the last kindling stimulation. We also found that synaptophysin immunoreactivity was lowest in CA3 near the hilus and increased with increasing distance from the hilus, a reverse pattern to that seen with Timm stains in stratum oriens following kindling. Furthermore, synaptophysin immunoreactivity was lowest in dorsal and greatest in ventral sections of both CA3 and dentate gyrus in both kindled and non-kindled animals. This demonstrates that different populations of sprouting axons are labeled by these two techniques, and suggests that activation-induced sprouting extends well beyond the hippocampal mossy fiber system.

Sustained improvement of cognition and global function in patients with moderately severe Alzheimer's disease: a double-blind, placebo-controlled study with the neurotrophic agent Cerebrolysin

BACKGROUND

In a recent study, Cerebrolysin (Cere), a compound with neurotrophic activity, has been shown to be effective in the treatment of mild to moderate Alzheimer's disease (AD). A subgroup analysis of this double-blind, placebo-controlled study was performed to assess the effects of Cere in cases with more advanced forms of AD.

PATIENTS AND METHODS

Patients received infusions of 30 ml Cere or placebo five days/week for four weeks. This treatment was repeated after a two-months therapy-free interval. Effects on cognition, global function, behavioural symptoms and activities of daily living were evaluated 4, 12, 16, and 28 weeks after the beginning of the infusions. 109 patients with MMSE scores <20 were included in this analysis.

RESULTS

The responder rate of the Cere group was 65% on the CGI, compared to 24.5% in the placebo group (p < 0.004). In the ADAS-cog, a score difference of 4.1 points in favour of Cere was observed (p < 0.0001). Notably, improvements were largely maintained in the Cere group up to the week 28 visit.

CONCLUSION

The data clearly demonstrate the efficacy of Cere treatment in moderate to severe forms of AD with sustained treatment effects on cognition and global function even after discontinuation of treatment.

Improved global function and activities of daily living in patients with AD: a placebo-controlled clinical study with the neurotrophic agent Cerebrolysin

BACKGROUND

Cerebrolysin (Cere) is a peptidergic, neurotrophic drug which has been shown to improve cognitive performance and global function of Alzheimer's disease (AD) patients in earlier trials. In this study, we have attempted to replicate this findings with particular emphasis on functional improvement of the patients.

PATIENTS AND METHODS

Patients received infusions of 30 ml Cere or placebo five days/week for six consecutive weeks. Patients had to have a diagnosis of AD and a MMSE score of 14-25 inclusive. Effects on cognition, global function, and activities of daily living were evaluated 3, 6, and 18 weeks after the beginning of the infusions.

RESULTS

Significant improvement of cognitive function, clinical global impression and activities of daily living were seen after the end of the therapy. The effects were most pronounced in the DAD score, a measure for the capability to perform activities of daily living. Interestingly, and in line with the findings of earlier studies, the treatment effect of Cere was maintained after cessation of treatment up to the week 18 assessment.

CONCLUSION

The data confirm the findings of earlier trials and clearly demonstrates that Cere leads to functional improvement of patients with AD. The sustained treatment effect of Cere after withdrawal has been confirmed.

Increased density of glutamate receptor subunit 1 due to Cerebrolysin treatment: an immunohistochemical study on aged rats

Glutamate receptor subunit 1 (GluR1) is one of the four possible subunits of the AMPA-type glutamate receptor. The integrity of this receptor is crucial for learning processes. However, reductions of GluR1 are noticeable in the hippocampal formation of patients suffering from Alzheimer's disease. Such degradations presumably result in an impaired synaptic communication and might be causally linked to the neurodegenerative process in this cognitive disorder. The peptidergic drug Cerebrolysin counteracts cognitive deficits of patients affected by Alzheimer's disease. These findings are supported by experiments revealing neuroprotective and neurotrophic capacities of the drug. In order to examine the effect of the drug on the density of GluR1 in hippocampal formation 24-month-old rats were treated with either Cerebrolysin or its peptide fraction E021, or saline as a control. Spatial navigation of the animals was tested in the Morris water maze. Rat brain slices were stained immunohistochemically with a GluR1-specific antibody. GluR1 immunoreactivity was quantified using light microscopy and a computerised image analysis system. Cerebrolysin and E021 increased GluR1 density in most measured regions of the hippocampal formation in a highly significant way. These results correlate with the behavioural outcome, revealing an improvement in learning and memory of these rats after treatment with Cerebrolysin and E021.

A 28-week, double-blind, placebo-controlled study with Cerebrolysin in patients with mild to moderate Alzheimer's disease

Cerebrolysin (Cere) is a compound with neurotrophic activity which has been shown to be effective in the treatment of Alzheimer's disease (AD) in earlier trials. The efficacy and safety of repeated treatments with Cere were investigated in this randomized, double-blind, placebo-controlled, parallel-group study. One hundred and forty-nine patients were enrolled (76 Cere; 73 placebo). Patients received i.v. infusions of 30 ml Cere or placebo 5 days per week for 4 weeks. This treatment was repeated after a 2-month therapy-free interval. Effects on cognition and clinical global impressions were evaluated 4, 12, 16, and 28 weeks after the beginning of the infusions using the Clinical Global Impression (CGI) and the Alzheimer's Disease Assessment Scale-cognitive subpart (ADAS-cog). All assessments, including the 28-week follow-up visit were performed under double-blind conditions. At week 16, the responder rate of the Cere group was 63.5% on the CGI, compared to 41.4% in the placebo group (P < 0.004). In the ADAS-cog, an efficacy difference of 3.2 points in favour of Cere was observed (P < 0.0001). Notably, improvements were largely maintained in the Cere group until week 28, 3 months after the end of treatment. Adverse events were recorded in 43% of Cere and 38% of placebo patients. Cere treatment was well tolerated and led to significant improvement in cognition and global clinical impression. A sustained benefit was still evident 3 months after drug withdrawal.

Two peptidergic drugs increase the synaptophysin immunoreactivity in brains of 6-week-old rats

An increase of synaptic density has been found in the hippocampus, the dendate gyrus and in the entorhinal cortex of 6-week-old rats after 7 days of treatment with the peptidergic drug Cerebrolysin, its peptide preparation E021 and the diluted peptide preparation E021dil. Rats received drugs on postnatal days 1-7 (2.5 ml/kg, each day). Controls received saline. The animals were sacrificed on days 42-48 of their life, after they had undergone behavioural testing in a Morris water maze. Slices of brain were stained immunohistochemically with anti-synaptophysin, a specific marker of presynaptic terminals. The synaptophysin-immunoreactivity of presynaptic terminals was quantified using light microscopy and a computerised image analysis system. Our results showed that rats benefit from the treatment with both drugs. A significant increase in the number of synaptophysin-immunoreactive presynaptic terminals was found in the entorhinal cortex and the hippocampal subfields CA1, CA2, CA3 stratum radiatum and CA3 stratum lucidum. The increased immunoreactive presynaptic terminals found in the present study are in accordance with the positive effects of the drugs on spatial learning and memory in young rats (Gschanes & Windisch 1999).

The drug cerebrolysin and its peptide fraction E021 increase the abundance of the blood-brain barrier GLUT1 glucose transporter in brains of young and old rats

The brain-derived peptidergic drug Cerebrolysin has been found to support the survival of neurons in vitro and in vivo. In the present study, we investigated the effects of Cerebrolysin and its peptide preparation E021 on spatial learning and memory, as well as on the abundance of the blood-brain barrier GLUT1 glucose transporter (GLUT1) in 2-month-old and 24-month-old rats. Young rats were treated with the drugs or saline (2.5 ml/kg/day) daily on postnatal days 1-7, and old rats for 19 consecutive days. For behavioural testing the Morris water maze was used. The abundance of GLUT1 was determined in brain slices by immunocytochemistry. Quantification of the density of the GLUT1 immunostaining was performed using light microscopy and a computerised image analysing system. All drug-treated rats, young and old, exhibit shorter escape latencies in the water maze, on all testing days (p < 0.01), indicating improved cognitive performance. Immunohistochemical data show an age-related decrease of the density of GLUTI (p < 0.05). In young animals, the administration of the drugs led to an increase of the abundance of GLUT1 in all experimental groups (p < 0.01). In old rats, the treatment with Cerebrolysin, but not with E021, resulted in an increase in the immunoreactive GLUT1 (p < 0.01). The elevated abundance of GLUT1 after the administration of both peptidergic substances might be supportive for the cognitive effects of this drug, by causing an improved nutritional supply of glucose to the neurons.