Effects of nicergoline on age-related decrements in radial maze performance and acetylcholine levels

Dihydroergotamine protects against ischemic stroke by modulating microglial/macrophage polarization and inhibiting inflammation in mice

OBJECTIVES

The search for drugs that can protect the brain tissue and reduce nerve damage in acute ischemic stroke has emerged as a research hotspot. We investigated the potential protective effects and mechanisms of action of dihydroergotamine against ischemic stroke.

METHODS

C57BL/6 mice were subjected to middle cerebral artery occlusion (MCAO), and dihydroergotamine at a dose of 10 mg/kg/day was intraperitoneally injected for 14 days. Adhesive removal and beam walking tests were conducted 1, 3, 5, 7, 10, and 14 days after MCAO surgery. Thereafter, the mechanism by which dihydroergotamine regulates microglia/macrophage polarization and inflammation and imparts ischemic stroke protection was studied using enzyme-linked immunosorbent assay, immunofluorescence staining, and western blotting.

RESULTS

From the perspective of a drug repurposing strategy, dihydroergotamine was found to inhibit oxygen-glucose deprivation damage to neurons, significantly improve cell survival rate, and likely exert a protective effect on ischemic brain injury. Dihydroergotamine significantly improved neural function scores and survival rates and reduced brain injury severity in mice. Furthermore, dihydroergotamine manifests its protective effect on ischemic brain injury by reducing the expression of TNF-α and IL-1β in mouse ischemic brain tissue, inhibiting the polarization of microglia/macrophage toward the M1 phenotype and promoting polarization toward the M2 phenotype.

CONCLUSION

This study is the first to demonstrate the protective effect of dihydroergotamine, a first-line treatment for migraine, against ischemic nerve injury in vitro and in vivo.

A clinical trial of nicergoline to prevent temporary threshold shift

Objective

To evaluate the effectiveness of nicergoline to prevent temporary threshold shift (TTS) in military personnel.

Study Design

A randomized control trial.

Methods

Two hundred and twenty‐four participants were enrolled. Nicergoline 30 mg twice daily intake was prescribed to the study group (n = 119) for 3 weeks. The placebo was prescribed to the control group (n = 105) for 3 weeks, as well. Audiometric thresholds were measured at baseline and within 24 h after the participants attended a 1‐day weapons firing practice. During the firing practice, all participants had to wear foam earplugs. The TTS was assessed by using a variety of published significant threshold shift (STS) definitions. Additionally, the effects of the treatment group on the magnitude of pre‐ to postexposure threshold shifts were estimated. Tinnitus and other adverse effects of the medication were recorded.

Results

The incidence of STS was 65.4% from the study group and 75% from the control group. The negative STS (thresholds improved) was 68.6% from the study group and 44.7% from the control group. The positive STS (thresholds worsened) from the study group and the control group was 31.4% and 55.3%, respectively. The effect of treatment in participants receiving nicergoline demonstrated significant coefficients (change in dB) in both ears (p = .001). The mean different threshold of participants receiving nicergoline showed negative STS in all tested frequencies without statistical significance. However, the mean different threshold of participants receiving a placebo showed positive STS with statistical significance. Additionally, there were 16 ears detecting a warning sign of permanent hearing loss. These participants from the control group presented a longer duration of tinnitus (p = .042). Moreover, the serious adverse effects of nicergoline were considerably low.

Conclusion

The study results suggest that nicergoline may attenuate noise‐related TTS and tinnitus, and justify further investigation on the effectiveness of this drug as an otoprotectant.

Level of Evidence

2

Phosphodiesterase Inhibitors for Alzheimer's Disease: A Systematic Review of Clinical Trials and Epidemiology with a Mechanistic Rationale

BACKGROUND

Preclinical studies, clinical trials, and reviews suggest increasing 3',5'-cyclic adenosine monophosphate (cAMP) and 3',5'-cyclic guanosine monophosphate (cGMP) with phosphodiesterase inhibitors is disease-modifying in Alzheimer's disease (AD). cAMP/protein kinase A (PKA) and cGMP/protein kinase G (PKG) signaling are disrupted in AD. cAMP/PKA and cGMP/PKG activate cAMP response element binding protein (CREB). CREB binds mitochondrial and nuclear DNA, inducing synaptogenesis, memory, and neuronal survival gene (e.g., brain-derived neurotrophic factor) and peroxisome proliferator-activated receptor-γ coactivator-1α (PGC1α). cAMP/PKA and cGMP/PKG activate Sirtuin-1, which activates PGC1α. PGC1α induces mitochondrial biogenesis and antioxidant genes (e.g.,Nrf2) and represses BACE1. cAMP and cGMP inhibit BACE1-inducing NFκB and tau-phosphorylating GSK3β.

OBJECTIVE AND METHODS

We review efficacy-testing clinical trials, epidemiology, and meta-analyses to critically investigate whether phosphodiesteraseinhibitors prevent or treat AD.

RESULTS

Caffeine and cilostazol may lower AD risk. Denbufylline and sildenafil clinical trials are promising but preliminary and inconclusive. PF-04447943 and BI 409,306 are ineffective. Vinpocetine, cilostazol, and nicergoline trials are mixed. Deprenyl/selegiline trials show only short-term benefits. Broad-spectrum phosphodiesterase inhibitor propentofylline has been shown in five phase III trials to improve cognition, dementia severity, activities of daily living, and global assessment in mild-to-moderate AD patients on multiple scales, including the ADAS-Cogand the CIBIC-Plus in an 18-month phase III clinical trial. However, two books claimed based on a MedScape article an 18-month phase III trial failed, so propentofylline was discontinued. Now, propentofylline is used to treat canine cognitive dysfunction, which, like AD, involves age-associated wild-type Aβ deposition.

CONCLUSION

Phosphodiesterase inhibitors may prevent and treat AD.

Changes in Regional Cerebral Perfusion after Nicergoline Treatment in Early Alzheimer's Disease: A Pilot Study

Background and Purpose

Nicergoline is an ergoline derivative that is used to treat cognitive deficits in cerebrovascular disease and various forms of dementia. Although therapeutic effects of nicergoline have been established, little is known about its effects on cerebral perfusion in Alzheimer's disease (AD). The aim of this study was to examine the role of nicergoline in regional cerebral blood flow (rCBF) of AD patients using technetium-99m hexa-methyl-propylene-amine-oxime single photon emission computed tomography (SPECT).

Methods

Sixteen patients with early AD underwent a comprehensive clinical assessment including cognitive testing and SPECT scans before and after nicergoline treatment. Nicergoline (30 mg twice daily) was administered for an average duration of 1.5 years. Clinical and cognitive functioning was assessed using the Mini-Mental State Examination, Clinical Dementia Rating (CDR), CDR-Sum of Boxes, Global Deterioration Scale, Barthel Activities of Daily Living Index, Instrumental Activities of Daily Living, and Geriatric Depression Scale.

Results

Nicergoline treatment induced changes in the severity of dementia, cognitive function, activities of daily living, and depressive symptoms, which were not statistically significant. During the follow-up, the patients showed significant increases in their relative rCBF in the superior frontal gyrus, precentral gyrus, and postcentral gyrus.

Conclusions

Nicergoline treatment improves perfusion of the frontal and parietal regions in early AD patients. It is possible that the increased perfusion in the superior frontal gyrus may be related to the mechanisms that delay or prevent progressive deterioration of cognitive functions in AD.

Neurotransmitter signaling pathways required for normal development in Xenopus laevis embryos: a pharmacological survey screen

Neurotransmitters are not only involved in brain function but are also important signaling molecules for many diverse cell types. Neurotransmitters are widely conserved, from evolutionarily ancient organisms lacking nervous systems through man. Here, results are reported from a loss- and gain-of-function survey, using pharmacological modulators of several neurotransmitter pathways to examine possible roles for these pathways in normal embryogenesis. Applying reagents targeting the glutamatergic, adrenergic and dopaminergic pathways to embryos of Xenopus laevis from gastrulation to organogenesis stages, we observed and quantified numerous malformations, including craniofacial defects, hyperpigmentation, muscle mispatterning and miscoiling of the gut. These data implicate several key neurotransmitters in new embryonic patterning roles, reveal novel earlier stages for processes involved in eye development, suggest new targets for subsequent molecular-genetic investigation, and highlight the necessity for in-depth toxicology studies of psychoactive compounds to which human embryos might be exposed during pregnancy.

Therapeutic use of nicergoline

The ergot alkaloid derivative nicergoline became clinically available about 35 years ago in the 1970s. Nicergoline has a broad spectrum of action: (i) as an alpha(1)-adrenoceptor antagonist, it induces vasodilation and increases arterial blood flow; (ii) it enhances cholinergic and catecholaminergic neurotransmitter function; (iii) it inhibits platelet aggregation; (iv) it promotes metabolic activity, resulting in increased utilization of oxygen and glucose; and (v) it has neurotrophic and antioxidant properties. Acting on several basic pathophysiological mechanisms, nicergoline has therapeutic potential in a number of disorders. This article provides an overview of the published clinical evidence relating to the efficacy and safety of nicergoline (30 mg twice daily) in the treatment of dementia (including Alzheimer's disease and vascular dementia) and vascular and balance disorders. For dementia of different aetiologies, the therapeutic benefit of nicergoline has been established, with up to 89% of patients showing improvements in cognition and behaviour. After as little as 2 months of treatment, symptom improvement is apparent compared with placebo, and most patients are still improved or stable after 12 months. Concomitant neurophysiological changes in the brain indicate (after only 4-8 weeks' treatment) improved vigilance and information processing. In patients with balance disorders, mean improvements of 44-78% in symptom severity and quality of life have been observed with nicergoline. Although clinical experience with nicergoline in vascular disorders is limited to relatively short-term, small-scale studies, it has been successfully used in rehabilitation therapy of patients with chronic ischaemic stroke. Open-label evaluations suggest that nicergoline may also be valuable in glaucoma, depression and peripheral arterio-pathy. Adverse events of nicergoline, if any, are related to the central nervous system, the metabolic system and the overall body. Most are considered typical symptoms of ergot derivatives. Because of their generally mild and transient nature, treatment discontinuations occur relatively infrequently. The efficacy of nicergoline combined with a favourable safety and tolerability profile at commonly applied doses (60 mg/day) make this agent a valuable therapy in patients with mild to moderate dementia, vascular diseases and balance disorders.

Spatial reference- (not working- or procedural-) memory performance of aged rats in the water maze predicts the magnitude of sulpiride-induced facilitation of acetylcholine release by striatal slices

Cluster analysis of water-maze reference-memory performance distinguished subpopulations of young adult (3-5 months), aged (25-27 months) unimpaired (AU) and aged impaired (AI) rats. Working-memory performances of AU and AI rats were close to normal (though young and aged rats differed in exploration strategies). All aged rats showed impaired procedural-memory. Electrically evoked release of tritium was assessed in striatal slices (preloaded with [(3)H]choline) in the presence of oxotremorine, physostigmine, atropine+physostigmine, quinpirole, nomifensine or sulpiride. Aged rats exhibited reduced accumulation of [(3)H]choline (-30%) and weaker transmitter release. Drug effects (highest concentration) were reductions of release by 44% (oxotremorine), 72% (physostigmine), 84% (quinpirole) and 65% (nomifensine) regardless of age. Sulpiride and atropine+physostigmine facilitated the release more efficiently in young rats versus aged rats. The sulpiride-induced facilitation was weaker in AI rats versus AU rats; it significantly correlated with reference-memory performance. The results confirm age-related alterations of cholinergic and dopaminergic striatal functions, and point to the possibility that alterations in the D(2)-mediated dopaminergic regulation of these functions contribute to age-related reference-memory deficits.

[1-13C]Glucose entry in neuronal and astrocytic intermediary metabolism of aged rats. A study of the effects of nicergoline treatment by 13C NMR spectroscopy

Age-related changes in glucose utilization through the TCA cycle were studied using [1-13C]glucose and 13C, 1H NMR spectroscopy on rat brain extracts. Significant increases in lactate levels, as well as in creatine/phosphocreatine ratios (Cr/PCr), and a decrease in N-acetyl-aspartate (NAA) and aspartate levels were observed in aged rat brains as compared to adult animals following glucose administration. The total amount of 13C from [1-13C]glucose incorporated in glutamate, glutamine, aspartate and GABA was significantly decreased in control aged rat brains as compared to adult brains. The results showed a decrease in oxidative glucose utilization of control aged rat brains. The long-term nicergoline treatment increased NAA and glutamate levels, and decreased the lactate levels as well as the Cr/PCr ratios in aged rat brains as compared to adult rats. The total amount of 13C incorporated in glutamate, glutamine, aspartate, NAA and GABA was increased by nicergoline treatment, showing an improvement in oxidative glucose metabolism in aged brains. A significant increase in pyruvate carboxylase/pyruvate dehydrogenase activity (PC/PDH) in the synthesis of glutamate in nicergoline-treated aged rats is consistent with an increase in the transport of glutamine from glia to neurons for conversion into glutamate. In adult rat brains, no effect of nicergoline on glutamate PC/PDH activity was observed, although an increase in PC/PDH activity in glutamine was, suggesting that nicergoline affects the glutamate/glutamine cycle between neurons and glia in different ways depending on the age of animals. These results provide new insights into the effects of nicergoline on the CNS.

Intrastriatal infusions of methoctramine improve memory in cognitively impaired aged rats

Alterations of striatal cholinergic markers may correlate with cognitive impairments in aged rats. M2 muscarinic receptors were found to be presynaptic inhibitory autoreceptors on striatal cholinergic interneurons. The effect of bilateral intrastriatal infusions of the M2 muscarinic receptor antagonist methoctramine was assessed, in cognitively impaired aged (24-26 months) Long-Evans female rats, on memory performances in a water maze. Compared with vehicle infusions, methoctramine injected bilaterally (1 microg/side) in the dorsolateral striatum, significantly improved procedural memory performance while having no effect on spatial working memory. Our results suggest that, in cognitively impaired aged rats, the blockade of M2 muscarinic receptors in the dorsolateral striatum improves procedural memory probably by enhancing the release of acetylcholine.

Neuroprotection and aging of the cholinergic system: a role for the ergoline derivative nicergoline (Sermion)

The aging brain is characterized by selective neurochemical changes involving several neural populations. A deficit in the cholinergic system of the basal forebrain is thought to contribute to the development of cognitive symptoms of dementia. Attempts to prevent age-associated cholinergic vulnerability and deterioration therefore represent a crucial point for pharmacotherapy in the elderly. In this paper we provide evidence for the protective effect of nicergoline (Sermion) on the degeneration of cholinergic neurons induced by nerve growth factor deprivation. Nerve growth factor deprivation was induced by colchicine administration in rats 13 and 18 months old. Colchicine induces a rapid and substantial down-regulation of choline acetyltransferase messenger RNA level in the basal forebrain in untreated adult, middle-aged and old rats. Colchicine failed to cause these effects in old rats treated for 120 days with nicergoline 10 mg/kg/day, orally. Moreover, a concomitant increase of both nerve growth factor and brain-derived neurotrophic factor content was measured in the basal forebrain of old, nicergoline-treated rats. Additionally, the level of messenger RNA for the brain isoform of nitric oxide synthase in neurons of the basal forebrain was also increased in these animals. Based on the present findings, nicergoline proved to be an effective drug for preventing neuronal vulnerability due to experimentally induced nerve growth factor deprivation.

Plasticity of GABA(a) system during ageing: focus on vestibular compensation and possible pharmacological intervention

The lesion of the vestibular end organ evokes static and dynamic symptoms, which spontaneously regress during a complex process known as 'vestibular compensation'. Vestibular compensation is age-dependent and involves several transmitter-identified pathways in the central nervous system. In this paper we studied the time course of vestibular compensation in adult (3 months) and old (24 months) rats and correlated behavioral recovery with modifications of glutamic acid decarboxylase (GAD) mRNA expression and benzodiazepine receptor density in different brain areas. Compensation in adult rats was complete 28 days after hemilabyrinthectomy, whereas old rats still showed significant behavioral impairment. A higher GABAergic tone was found in old rats, as indicated by higher benzodiazepine receptor density in lateral vestibular nucleus and higher mRNA level for glutamic acid decarboxylase in cerebral cortex and medial vestibular nucleus. In adult, compensated rats, benzodiazepine receptor density in the vestibular nuclei was normal 28 days after lesion, whereas GAD mRNA level was higher in anterior cingulate cortex, only. On the contrary, these parameters were still altered in anterior cingulate and somatosensory cortex, basal ganglia, vestibular nuclei and cerebellum in old rats 28 days after vestibular lesion. We also evaluated the effect of the ergoline derivative nicergoline on behavioral and neurochemical correlates of vestibular compensation in old rats. Nicergoline treatment attenuated the severity of oculomotor and postural symptoms after vestibular lesion and reversed most of these age- and lesion-induced alterations in GAD mRNA expression. Thus, lesion-related alterations of the GABAergic transmission and behavioral profile after vestibular lesion are age-dependent.

Efficacy of nicergoline in dementia and other age associated forms of cognitive impairment

BACKGROUND

Nicergoline is an ergot derivative currently in use in over fifty countries for more than three decades, for the treatment of cognitive, affective, and behavioral disorders of older people. It was initially considered as a vasoactive drug and mainly prescribed for cerebrovascular disorders. Recent findings suggest other actions which has provided a rationale for the use of nicergoline for the treatment of various forms of dementia, including Alzheimer's Disease.

OBJECTIVES

To determine whether there is evidence of efficacy of nicergoline in the treatment of dementia and other age-associated forms of cognitive decline,and to assess the safety and tolerability of the drug.

SEARCH STRATEGY

1. Electronic databases search. The Cochrane Controlled Trials Register (which contains citations from the MEDLINE, EMBASE, Psych LIT, and hand searches of geriatric, dementia, psychogeriatric journals, and conference abstracts) was searched using the following terms: 'Nicergoline', 'Sermion'. 2. Reference search. The reference lists of all obtained studies was checked. 3. Pharmaceutical company Pharmacia & Upjohn, owners of the rights to produce and market nicergoline in various different countries, was asked to provide data and reports of clinical trials. In case of unavailability of numerical data in published studies, the authors of each paper, were asked for any published or unpublished data.

SELECTION CRITERIA

- All unconfounded, double-blind, randomized, placebo-controlled, published and unpublished trials were sought. Non-randomized trials were excluded. Open trials were considered for inclusion if patients were randomized to the different treatment groups. - All patients diagnosed as having dementia or other cognitive disorder defined according to classification criteria accepted at the time of each study. - Nicergoline given at any dose for more than one day with placebo control. Type of outcome variables: 1. Cognitive function (as measured by psychometric tests). 2. Clinical impression (such as CIBIC or other clinical global measures of change). 3. Functional performance including dependency. 4. Behavioural disturbance. 5. Safety and acceptability as measured by the incidence of adverse effects (including side-effects) leading to withdrawal. 6. Death 7. Effect on carer 8. Use of services 9. Quality of life.

DATA COLLECTION AND ANALYSIS

A comprehensive search of the international literature and the producing company archives has been performed to identify all possible sources of data for this review. Only those trials fulfilling the inclusion criteria of belonging to either category A or B of allocation concealment, as defined by the Cochrane Organisation, were examined for data extraction by one reviewer. If there was doubt then the other reviewer was consulted. Data availability restricted analyses to 'completers' analyses for the outcome measures. Outcomes able to be assessed included: Behaviour, Cognition, Clinical Judgment, Tolerability, EEG.

MAIN RESULTS

The Sandoz Clinical Assessment Geriatric Scale (SCAG) was the outcome used in the largest number of patients (814 patients). The results from these studies were homogeneous in nature despite including patients observed for periods of time ranging from 2 months to 12 months. There was a difference in favour of the active treatment in reducing the behavioural symptoms described by this scale, -5.18 points [-8.03, -2.33]. This scale has a maximum of 133 points. The therapeutic effects of nicergoline seem to be evident by 2 months of treatment and maintained for 6 months. In general other behavioural outcome measures which include the GRS, the IADL, and the MACC and were episodically used in few studies, failed to demonstrate statistically significant results although there was a trend favouring treatment. Cognitive assessment has been performed in a moderate number of patients with the MMSE (261 patients) and the ADAS-Cog (342 patients). No significant heterogeneity was found for these trials, despite the trials extending over periods of treatment of 3 to 12 months. There was a difference between treatment and control groups on the MMSE favouring nicergoline treatment. At 12 months the effect size was 2.86 [0.98, 4.74] The effect size for the ADAS-Cog, used exclusively with Alzheimer's disease patients, did not reveal a significant benefit. At 12 months the trend favoured treatment (-1.64 [-4.62, 1.34]). The other results from various cognitive measures tended to favour nicergoline but this was based on a small number of cases. The clinical impression of change obtained from a total of 921 patients was homogeneous across the studies, despite reflecting changes over periods of time ranging from 2 to 12 months. The Peto odd ratio for improvement in the subjects treated with nicergoline over these varying time periods was 3.33 [2.50, 4.43]. Tolerability assessed in 1427 patients was homogeneous across all studies and demonstrated a mildly increased risk of adverse events on treatment, OR 1.51[1.10, 2.07].

REVIEWER'S CONCLUSIONS

The clinical studies on nicergoline were carried out with diverse criteria and modalities of evaluation. Despite this, the 14 studies included in this review, have presented generally consistent results. Results of this meta-analysis provide some evidence of positive effects of nicergoline on cognition and behaviour and these effects are supported by an effect on clinical global impression. There was some evidence that there were increased risk of adverse effects associated with nicergoline. These results were obtained on older patients with mild to moderate cognitive and behavioural impairment of various clinical origins, including chronic cerebrovascular disorders and Alzheimer's dementia. The few studies specifically performed on patients with Alzheimer's disease were performed with too few people to give a definitive answer to the questions concerning the use of nicergoline for this form of dementia. This drug has not been evaluated using current diagnostic categories such as MCI or in association with therapeutic agents of different nature such as cholinesterase or antioxidant drugs.

Comparison of the effects of adrafinil, propentofylline, and nicergoline on behavior in aged dogs

OBJECTIVE

To compare the efficacy of adrafinil, propentofylline, and nicergoline for enhancing behavior of aged dogs.

ANIMALS

36 Beagles between 9 and 16 years old.

PROCEDURE

Dogs were randomly assigned to receive adrafinil (20 mg/kg of body weight, PO, q 24 h; n = 12), propentofylline (5 mg/kg, PO, q 12 h; 12), or nicergoline (0.5 mg/kg, PO, q 24 h; 12) for 33 days. Baseline behaviors in an open field and in kennels (home cage) were recorded before treatment. After treatment, behaviors in the open field were recorded 2 hours after drug administration on days 2, 15, and 28, and 10 hours after administration on days 7, 20, and 33. Behaviors in the home cage were recorded 2 and 7 hours after drug administration on days 4, 17, and 30.

RESULTS

Treatment with adrafinil resulted in a significant increase in locomotion in each of the open-field tests and an increase in locomotion in the home cage. This latter increase was smaller and more variable than that in the open field. Locomotion was not affected by treatment with propentofylline or nicergoline. In the open field, sniffing decreased over time in all 3 groups, but the largest decline was observed in the propentofylline group.

CONCLUSIONS AND CLINICAL RELEVANCE

Treatment with adrafinil may improve the quality of life of aged dogs by increasing exploratory behavior and alertness.

Eptastigmine improves eight-arm radial maze performance in aged rats

Eptastigmine, a potent and long-lasting cholinesterase inhibitor on age-related memory deficits, was studied. Four groups of 3-, 18-, 23- and 27-month-old Wistar rats were first submitted to spontaneous motor activity evaluation and then trained in an eight-arm radial maze until they reached the criterion. The effect of introducing a 2-h delay between the fourth and fifth choices was then evaluated under the influence of acute oral dose of eptastigmine (0.5 mgkg(-1)) 120 min before the test. Eptastigmine reversed the impairment observed in vehicle-treated rats at all the tested ages. Two naive groups of 3- and 18-month-old rats were treated twice a day for 30 days with eptastigmine ( 0.25 mgkg(-1)p.o.) or vehicle and trained daily in the maze. Subchronic administration did not affect the performance in young rats, while in 18-month-old rats, the mean number of days needed to reach the criterion decreased and the percentage of animals reaching the criterion increased when compared to the vehicle group. The 18-month-old rats (ex-eptastigmine and ex-vehicle) were then allowed to age in their home cage without any further treatment for an additional 5 and 9 months, until they reached 23 and 27 months. The ex-eptastigmine rats tested at 23 months, without any treatment, showed better performance than that observed in ex-vehicle rats. When the same rats were tested again at 27 months of age, no difference was seen in comparison with ex-vehicle rats. Eptastigmine might, therefore, be helpful for correcting age-related memory impairment attributed to cholinergic hypofunction.

Immunohistochemical and neurochemical correlates of learning deficits in aged rats

This study examined whether cholinergic and monoaminergic dysfunctions in the brain could be related to spatial learning capabilities in 26-month-old, as compared to three-month-old, Long-Evans female rats. Performances were evaluated in the water maze task and used to constitute subgroups with a cluster analysis statistical procedure. In the first experiment (histological approach), the first cluster contained young rats and aged unimpaired rats, the second one aged rats with moderate impairment and the third one aged rats with severe impairment. Aged rats showed a reduced number of choline acetyltransferase- and p75(NTR)-positive neurons in the nucleus basalis magnocellularis, and choline acetyltransferase-positive neurons in the striatum. In the second experiment (neurochemical approach), the three clusters comprised young rats, aged rats with moderate impairment and aged rats with severe impairment. Alterations related to aging consisted of reduced concentration of acetylcholine, norepinephrine and serotonin in the striatum, serotonin in the occipital cortex, dopamine and norepinephrine in the dorsal hippocampus, and norepinephrine in the ventral hippocampus. In the first experiment, there were significant correlations between water maze performance and the number of; (i) choline acetyltransferase- and p75(NTR)-positive neurons in the nucleus basalis magnocellularis; (ii) choline acetyltransferase-positive neurons in the striatum and; (iii) p75(NTR)-positive neurons in the medial septum. In the second experiment, water maze performance was correlated with the concentration of; (i) acetylcholine and serotonin in the striatum; (ii) serotonin and norepinephrine in the dorsal hippocampus; (iii) norepinephrine in the frontoparietal cortex and; (iv) with other functional markers such as the 5-hydroxyindoleacetic acid/serotonin ratio in the striatum, 3,4-dihydroxyphenylacetic acid/dopamine ratio in the dorsal hippocampus, 5-hydroxyindoleacetic acid/serotonin and homovanillic acid/dopamine ratios in the frontoparietal cortex, and 3,4-dihydroxyphenylacetic acid/dopamine ratio in the occipital cortex. The results indicate that cognitive deficits related to aging might involve concomitant alterations of various neurochemical systems in several brain regions such as the striatum, the hippocampus or the cortex. It also seems that these alterations occur in a complex way which, in addition to the loss of cholinergic neurons in the basal forebrain, affects dopaminergic, noradrenergic and serotonergic processes.

Nicergoline stimulates protein kinase C mediated alpha-secretase processing of the amyloid precursor protein in cultured human neuroblastoma SH-SY5Y cells

We investigated the ability of the antidementia agents, nicergoline, aniracetam and hydergine to stimulate PKC mediated alpha-secretase amyloid precursor protein (APP) processing in cultured human neuroblastoma SH-SY5Y cells. Western immunoblotting of cell conditioned media using the Mabs 22C11 and 6E10 revealed the presence of 2 bands with molecular mass of 90 and 120 kDa, corresponding to possible alternatively glycosylated forms of secreted APP (APPs). Short-term (30 min and 2 h) treatment of cells with nicergoline gave an increased intensity of both bands, compared to non-treated cells. Maximal nicergoline effects, of the order of 150-200% over basal APPs release, were seen at concentrations between 1 and 10 microM. Under the same condition, 1 microM PdBu, used as a positive control, gave 500-1000% increases of basal APPs release. In contrast, aniracetam and hydergine, did not show any effect on APPs secretion. 2 h treatment with nicergoline had no effect on cellular full-length APP levels, as determined by immunoblotting of cell extracts with 22C11 and CT15 antibodies. Immunoblotting with PKC isoform specific antibodies of soluble and membrane fractions prepared from 2 h treated cells, showed that nicergoline (50 microM) and PdBu (1 microM) both induced translocation of PKC alpha, gamma and epsilon, but not PKC beta. The involvement of PKC in mediating nicergoline stimulated APPs release was also studied using specific inhibitors. 1 microM calphostin C, a broad range PKC inhibitor, significantly reduced both PdBu (1 microM) and nicergoline (10 microM) induced APPs release. In contrast, Go6976 (1 microM), a selective PKC alpha and beta1 inhibitor, as well as the cAMP-dependent protein kinase inhibitor, H89 (1 microM) were without effect. These results indicate that nicergoline can modulate alpha-secretase APP processing by a PKC dependent mechanism that is likely to involve the gamma and epsilon isoforms of this enzyme.