L-deprenyl in Alzheimer's disease. Preliminary evidence for behavioral change with monoamine oxidase B inhibition

The clinical potential of Deprenyl in neurologic and psychiatric disorders

This article reviews the results of clinical studies with Deprenyl in various neurologic and psychiatric disorders except Parkinson's disease. Promising results could be observed both in narcolepsy in a dose of at least 20 mg/day in three different trials and in one study of Tourette's syndrome including attention hyperactivity disorders using an average dosis of 8.1 mg/ day. Controversial results were reported for Alzheimer's disease. On the one hand significant improvement of cognitive functions was found by various authors. On the other hand in a more recent study no effect on the progression of the disease could be observed. For depression a higher dosage of deprenyl between 30 to 60 mg/day appears to be necessary for effective treatment. No positive results were found in amyotrophic lateral sclerosis and in tardive dyskinesias.

The depressions of Alzheimer's disease: sorting, pharmacotherapy, and clinical advice

Research describing wide prevalence variation of Alzheimer's disease (AD) and comorbid depression is explained in light of subsyndromal depressions, the use of standardized diagnostic instruments and procedures, and the subcortical and cortical components of mood. There appear to be several "depressions" of AD. Against this backdrop, double-blind, placebo-controlled studies of antidepressant use in AD are reviewed and methodologic problems identified. Evidence for efficacy in controlled trials is weak, but open-label trials are, as expected, more encouraging. The potential efficacy of new agents for the depressions of AD receive comment. A heuristic model makes use of the conclusions developed, the stage of illness, and a preliminary classification scheme for the depressions of AD; this model provides a rational basis for thinking about medication selection for AD depressions. Clinical decisions are illustrated.

Anticonvulsant and other non-neuroleptic treatment of agitation in dementia

Studies have shown that the vast majority of patients with dementia experience some psychopathologic symptoms during the course of their illness. Symptoms of this nature, which can include frightening hallucinations or anxiety of phobic proportions, are subjectively distressing and can lead both to unsafe or violent situations as well as to the preventable use of inappropriate medication, physical restraint, and frequently to institutionalization. These psychopathologic manifestations of dementia often prove to be a burden on family, caregivers, and the health care system as well. This article presents an overview of the assessment and management of agitation as it relates to the severity of dementia symptoms and cognitive deterioration. Specifically, the use of anticonvulsant and other non-neuroleptic therapies is examined.

A review of the effects of dopaminergic agents on humans, animals, and drug-seeking behavior, and its implications for medication development. Focus on GBR 12909

Medication development for cocaine abuse has focused on potential mechanisms of action related to the abuse of cocaine. The hypothesis that mesolimbic dopamine (DA) is the key neurochemical mediator of cocaine's addictive and reinforcing effects is well supported by a wide variety of data from animal studies. On the other hand, medications that increase DA or block its action in humans can produce effects that appear incompatible with this hypothesis. This article reviews these incompatibilities between animal and human data with a focus on the DAergic actions of drugs, including DA reuptake inhibitors, direct DA agonists, DA increasers, and DA antagonists. Possible reasons for these discrepancies are discussed, and the potential role of high-affinity DA uptake inhibitors, such as GBR12909, for pharmacotherapies for treating cocaine addiction in humans is likely to come from understanding its mechanisms of action, it is clear that further research on the effects of cocaine in humans and animals will be critical to the medication development effort.

Lack of protective effect of R(-)-deprenyl on programmed cell death of mouse thymocytes induced by dexamethasone

R(-)-Deprenyl, an archetypical MAO-B inhibitor, has been shown to delay the onset of the disabling syndrome of Parkinson's disease and to be useful in the treatment of Alzheimer's disease. Recently, R(-)-deprenyl has been claimed to be capable of preventing apoptosis of PC12 cells, which had been primed with nerve growth factor (NGF) and followed by withdrawal of serum. We investigated the effect of R(-)-deprenyl in a non-neuronal cell model, namely, apoptosis of mouse thymocytes induced by dexamethasone. Trypan blue exclusion and lactate dehydrogenase activity were applied to assess the cell survival. R(-)-Deprenyl did not exhibit any detectable protective effect to the thymocytes from apoptosis. The result is further confirmed by examining the apoptotic DNA fragmentation using gel electrophoresis and assessing the soluble DNA released by a spectrophotometric method.

Pharmacotherapy of cognitive impairment in Alzheimer's disease: a review

Experimental pharmacotherapy of cognitive impairment in Alzheimer's disease has seen a recent proliferation of drug trials involving a wide variety of drugs. Many of the earlier studies focused on cholinergic agents. However, subsequent advances in basic and biological sciences have broadened the scope of therapeutic strategies beyond the neurotransmitter approaches to include neurotrophic, metabolic-enhancing, membrane-modifying, and antitoxic agents, and have also provided rationale for developing antiamyloid and anti-infective therapies. For the clinician, it has not been easy to keep abreast of these developments. In this article, I present an overview of the cognition-enhancing drugs that have been used in the past, of those currently under investigation, and of new drugs and strategies that are likely to receive attention in the next few years.

Rationale for (-)deprenyl (selegiline) medication in Parkinson's disease and in prevention of age-related nigral changes

(-)Deprenyl (selegiline, jumex, eldepryl, movergan), a close structural relative to phenylethylamine (PEA), is a drug with a unique pharmacological spectrum. It is a highly potent and selective, irreversible inhibitor of B-type monoamine oxidase (MAO), a predominantly glial enzyme in the brain. The activity of this enzyme significantly increases with age. (-)deprenyl, the first selective inhibitor of MAO-B described in literature, has become the universally used research tool for selectively blocking B-type MAO. It is the only selective MAO-B inhibitor in clinical use. (-)Deprenyl interferes with the uptake of catecholamines and indirectly acting sympathomimetics because it is handled by the catecholaminergic neuron in a way similar to the physiological substances transported through the axonal end organ and vesicular membrane. The unique behavior of (-)deprenyl is that, in striking contrast to PEA and its relatives it does not displace the transmitter from storage, ie it is not a releaser. The net result is that (-)deprenyl inhibits the releasing effect of tyramine, and at present, is the only safe MAO inhibitor that can be administered without dietary precautions. Maintenance on (-)deprenyl selectively enhances superoxide dismutase (SOD) and catalase activity in the striatum. This effect is unrelated to its effect on MAO-B and the inhibitory effects of the drug on neurotransmitter uptake. Maintenance on (-)deprenyl facilitates the activity of the catecholaminergic system in the brain, and this effect, too, is unrelated to either its effects on MAO or on neurotransmitter uptake. (-)Deprenyl protects the nigrostriatal dopaminergic neurons against selective neurotoxins (6-hydroxydopamine, MPTP, DSP-4).(ABSTRACT TRUNCATED AT 250 WORDS)

Aliphatic propargylamines, a new series of potent selective, irreversible non-amphetamine-like MAO-B inhibitors. Their structures, function and pharmacological implications

1-Deprenyl, a selective irreversible MAO-B inhibitor, has been shown to prolong the onset of disability in Parkinson's patients and to improve cognitive behavior in Alzheimer's disease. It has been claimed that 1-deprenyl exhibits neuroprotective and neurorescue effects in several animal models. The precise mechanism of these effects is unknown. It is yet to be established whether or not the effects are unique to 1-deprenyl; a drug which possesses, in addition to inhibition of MAO-B activity, an amphetamine moiety. Based on the fact that several N-methylpropargylamine derivatives have been shown to be MAO inhibitors and that aliphatic amines are typical MAO-B substrates with a high affinity for the enzyme, we have synthesized a series of aliphatic propargylamines which have turned out to be highly potent, selective and irreversible MAO-B inhibitors, structurally unrelated to amphetamine. The potency of these inhibitors is related to their chain length and the substitution of a hydrogen on the terminal carbon of the aliphatic chain. MAO-I activity, as assessed in vitro, increased as the aliphatic carbon chain length increased; substitution of the hydrogen at the aliphatic chain terminal by hydroxyl, carboxyl or carboethoxyl groups or replacement of the methyl group on the nitrogen atom by an ethyl group considerably reduced their inhibitory activity. Stereospecific effects were observed with the R-(-)-enantiomer being 20-fold more active than the S-(+)-enantiomer. Inhibitors with relatively short carbon chain lengths (i.e. four to six carbons) were found to be more potent at inhibiting brain MAO-B activity in vivo especially after oral administration.(ABSTRACT TRUNCATED AT 250 WORDS)

Can an adjuvant treatment or a pharmacologic prevention be common to several diseases? The case of those associated to neuromediator defects

The author has tried to extrapolate on several neurological diseases of the ageing, Knoll's proposition to treat Parkinson's disease chronically for relapse prevention, by MAO-B. At this occasion, the author makes a critical review of the clinical trial results concerning the new different series of depression treatments, as most authors propose today to use some new ones not only in depression, but in Parkinson's and Alzheimer's diseases and in ageing.

Neurochemical, neuroprotective and neurorescue effects of aliphatic N-methylpropargylamines; new MAO-B inhibitors without amphetamine-like properties

A series of aliphatic N-methylpropargylamine MAO-B inhibitors have been synthesized and their structural and functional relationships have been investigated. 2-Hexyl-N-methylpropargylamine (2-HxMP), for example, has been found to be a highly potent, irreversible, selective, MAO-B inhibitor both in vitro and in vivo. The R-(-)-enantiomers are much more active than the S-(+)-enantiomers at inhibiting MAO-B activity. Some of these compounds protect mouse nigrostriatal dopamine neurons against the neurotoxin MPTP and the mouse hippocampal noradrenergic system against the neurotoxin N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4). They rescue hippocampal neurons after damage induced by ischemia and kainic acid treatment, as well as motoneurons in young mice following facial nerve axotomy. Such rescue effects are, interestingly, unrelated to inhibition of MAO-B activity. Some of the aliphatic propargylamines enhance the survival of neuroblastoma cells co-cultured with astrocytes following serum depletion. They stimulate the expression of AADC mRNA and inhibit GFAP mRNA expression. They do not possess amphetamine-like properties and exhibit no effect on noradrenaline or dopamine uptake nor do they increase hypertensive effects in the tyramine pressor test. Unlike R(-)-deprenyl, 2-HxMP does not potentiate dopamine toxicity in vitro. These new MAO-B inhibitors may possess significant chemotherapeutic implications for certain psychiatric and neurodegenerative disorders.

Inhibition by (-)-deprenyl of agonist-evoked contractions in rabbit aorta

The effect of (-)-deprenyl, a relatively selective MAO-B inhibitor, was examined for its ability to inhibit the contractions of rabbit isolated aorta evoked by various agonists and potassium. (-)-Deprenyl (10(-5)-3 x 10(-4) M) antagonized the contractions evoked by noradrenaline (10(-8)-3 x 10(-4) M); pA2: 5.10. The antagonism was reversible. It was attenuated by cocaine (3 x 10(-5) M); pA2: 4.38, unchanged by corticosterone (4 x 10(-5) M); pA2 4.79 and enhanced by cocaine (3 x 10(-5) M) plus corticosterone (4 x 10(-5) M); pA2: 5.48. (+)-Deprenyl (10(-6)-10(-4) M) did not alter the contractions evoked by noradrenaline (3 x 10(-9)-10(-4) M). Clorgyline (10(-5) and 10(-4) M) antagonized the noradrenaline-evoked contractions. Pargyline (10(-4) and 3 x 10(-4) M) had no effect. (-)-Deprenyl (10(-5)-3 x 10(-4) M) antagonized the contractions evoked by phenylephrine (10(-8)-10(-4) M); pA2: 5.10. Removal of the endothelium did not alter the antagonism; pA2: 5.35. (-)-Deprenyl (10(-5)-3 x 10(-4) M) antagonized the contractions evoked by either 5-hydroxytryptamine (3 x 10(-8)-3 x 10(-4) M); pA2: 4.61 or by histamine (10(-6)-3 x 10(-2) M); pA2: 4.84. (-)-Deprenyl (3 x 10(-4) M) caused a noncompetitive antagonism of the contractions evoked by potassium (1.5-5.5 x 10(-2) M). It is concluded that (-)-deprenyl is a weak inhibitor of postjunctional alpha 1-adrenoceptors, 5-hydroxytryptamine (5-HT2) receptors, and histamine (H1) receptors.

Pharmacological and clinical implications of MAO-B inhibitors

Although the involvement of monoamine oxidase B (MAO-B) in physiological function is not yet well understood, its inhibitors have been shown to be quite useful in the treatment of various neuropsychiatric disorders. Platelet MAO-B activity has been found to be reduced in several psychiatric disorders, related to substance abuse and associated with different personalities. 1-Deprenyl (selegiline), an archetypical MAO-B inhibitor, alone does not seem to exert an antidepressive effect, however, it may become useful when administered in combination with amine neurotransmitter precursors. MAO-B inhibitors are useful adjunct drugs to 1-DOPA in the symptomatic treatment of Parkinson's disease. Interestingly, 1-deprenyl alone can slow down the progress of otherwise disabled syndromes of Parkinson's disease. It has been proposed that 1-deprenyl may play a role in neuroprotection and neurorescue. MAO-B inhibitors can selectively and dramatically increase the level of beta-phenylethylamine, which has been shown to potentiate dopamine and noradrenaline function in the central nervous system. Several new types of highly selective, reversible and irreversible MAO-B inhibitors have recently been developed. The mechanism(s) of neuroprotective and rescue actions of 1-deprenyl and other MAO-B inhibitors will help to shed some light on our understanding of the neurodegenerative process.

Practical guidelines for the treatment of behavioural complications of dementia

A step-by-step approach to management of behavioural problems in dementia is outlined. Initial strategies include assessment of the underlying cause and consideration of non-pharmacological methods of treatment. If pharmacotherapy is required, the altered pharmacokinetics in the elderly and the variable efficacy of different psychotropic drugs should be kept in mind. Recommendations regarding drug dosage, monitoring and review are given.

Increased monoamine oxidase B activity in plaque-associated astrocytes of Alzheimer brains revealed by quantitative enzyme radioautography

The aetiology and pathogenesis of Alzheimer's disease are currently poorly understood, but symptomatic disease is associated with amyloid plaques, neurofibrillary tangles, neuronal loss and numerous alterations of neurotransmitter systems in the CNS. Monoamine oxidase type B is known to be increased in Alzheimer diseased brains. The distribution and abundance of catalytic sites for monoamine oxidases A and B in post mortem human brains of 11 Alzheimer disease cases and five age-matched controls were investigated by quantitative enzyme radioautography. Using tritiated monoamine oxidase inhibitors (Ro41-1049 and lazabemide)--as high affinity substrates selective for monoamine oxidases A and B, respectively--it was found that monoamine oxidase B activity increased up to three-fold exclusively in temporal, parietal and frontal cortices of Alzheimer disease cases compared with controls. This increase was restricted to discrete patches (approximately 185 microns in diameter) which occupied approximately 12% of the cortical areas examined. In other brain regions (hippocampal formation >> caudate-putamen > cerebellum), patches of [3H]lazabemide-enriched binding were less abundant. [3H]Ro41-1049 binding (i.e. monoamine oxidase A) was unchanged in all tissues of diseased versus control brains. The monoamine oxidase B-enriched patches in all cortical regions correlated, in their distribution and frequency, with glial fibrillary acidic protein-immunoreactive clusters of astrocytes. Diffuse and mature beta-amyloid-immunoreactive senile plaques as well as patches of high density binding of [3H]PK-11195--a high-affinity ligand for peripheral-type (mitochondrial) benzodiazepine binding sites in microglia/macrophages--were found throughout Alzheimer diseased cortices. The up-regulation of monoamine oxidase B in plaque-associated astrocytes in Alzheimer's disease--in analogy to its proposed role in neurodegenerative disorders such as Parkinson's disease--might, indirectly, be a potential source of cytotoxic free radicals. Lazabemide, a selective reversible monoamine oxidase B inhibitor, is currently under clinical evaluation for the treatment of Parkinson's and Alzheimer's diseases. We conclude that enzyme radioautography with [3H]lazabemide is a reliable high resolution assay for plaque-associated astroglioses in Alzheimer's disease. Its clinical diagnostic utility for positron emission tomography or single photon emission computer tomography studies is being investigated.

Emerging drugs for Alzheimer's disease. Mechanisms of action and prospects for cognitive enhancing medications

This article has discussed various possible pharmacologic approaches to Alzheimer's disease. Despite generally encouraging results, no agent to date has proved to be dramatically effective. At present, treatment options are limited for the clinicians. Tacrine is available on the market. In the doses recommended, efficacy is modest, and side effects require vigilance in monitoring. Other cholinesterase inhibitors may be approved for clinical use in the near future but are likely to have similar modest clinical effects. L-deprenyl is marketed for Parkinson's disease but has not been adequately tested for efficacy in Alzheimer's disease. Newer drugs in earlier stages of development are generally intended to affect cholinergic systems in various other ways. The effects of these drugs on behavioral symptoms, in severe dementia, and in non-Alzheimer's dementia have not been adequately assessed. In the absence of known cause, and in the face of uncertainty regarding pathophysiology, efforts in the near future will focus on encouraging theoretical leads, sensible empiric trials, and symptomatic treatment research. Although public anticipation will be raised over each announced "breakthrough," only results from carefully conducted trials should be accepted.

The management of other psychiatric states. Hallucinations, delusions, and other disturbances

The behavioral disturbances that are most common in Alzheimer's disease are not those directly associated with the core characteristics of the disease; however, they often cause the most difficult problems of management. These disturbances include agitation, hallucinations, and delusions. This article reviews their prevalence, etiology, differential diagnosis, and management.

Inability of (-)deprenyl to modify copulatory performance in the male rat, whether or not stimulated by the selective D2 dopamine agonist SND 919

Intraperitoneal injection of the selective D2 dopamine agonist SND 919 (0.1 and 1 mg kg-1) significantly accelerated the copulatory behaviour of sexually-active rats, diminishing the number of mounts, intromissions and latency to ejaculation. Subchronic (-)deprenyl did not produce any significant effect on the copulatory behaviour of sexually-active and -inactive male rats or modify the sexual stimulation exerted on the same sexually-active rats by SND 919, when acutely injected at 1 mg kg-1.

Neuropathobiology of senile dementia and mechanism of action of nootropic drugs

Recent advances in neuroscience and molecular neurochemistry have substantially increased the knowledge of the neuropathobiology of senile dementia and Alzheimer's disease. On the basis of various hypotheses concerning degenerative processes in aging brains, new therapeutic strategies have been developed, including nootropic drugs with different mechanisms of action and heterogenous chemical structures. Mutual relationships exist between neuroscientific research and nootropic drug development. To date, such areas of research and drug development have involved deficits of brain neurotransmission (cholinergic, monoaminergic, peptidergic), free radical-induced damage, disturbances of calcium homeostasis and excitatory amino acid function, and deposition of amyloid protein.

Advances in the pharmacotherapy of Alzheimer's disease

The authors reviewed the literature on the agents proposed for the treatment of Alzheimer's disease (AD). Different classes of drugs have been tested for this indication including psychostimulants, anticoagulants, vasodilators, hyperbaric oxygen, hormones, nootropics, cholinomimetics, monoaminergics and neuropeptides without conclusive evidence of being beneficial for the treatment of this condition. Among the cholinomimetics recent research data seems to indicate that they might produce modest benefits in mild-to-moderate AD patients. Recently, other drugs have also been proposed including neurotrophic factors, phosphatidylserine, angiotension [corrected] converting enzyme (ACE) inhibitors, calcium channel blockers, acetyl-L-carnitine, xanthine derivatives, anti-inflammatory agents, aluminum chelate agents, and D-cycloserine. Of these new strategies few hold promise of more substantial benefits for AD, with the possibility of altering the course of the disease, but these drugs await confirmatory trials.

Monoamine oxidase inhibitors, cognitive functions and neurodegenerative diseases

Recent data obtained in animals and in humans suggest that both MAO-A and MAO-B inhibitors present cognitive enhancing properties of possible interest in the treatment of cognitive disorders. In addition, the rational for using selegiline as a neuroprotector in Parkinson's disease may also be applicable in Alzheimer's disease in which a dramatic increase in the MAO-B activity has been reported. It seems then worthwhile to investigate the neuroprotective effect of MAOIs in humans and to assess, furthermore, the real therapeutical benefit of their cognitive enhancing properties.

Chronic L-deprenyl or L-amphetamine: equal cognitive enhancement, unequal MAO inhibition

The effect of chronic (4 month), subcutaneous injections of saline, L-deprenyl (0.25 mg/kg), or L-amphetamine (0.25 mg/kg) on the acquisition of a learned spatial habit in a modified Morris Water Maze was investigated in middle aged rats. Injections, given three times weekly starting at 6 months of age, were continued during behavioral testing, which occurred at 10 months of age. The cognitive performance of the middle aged rats was compared to that of 2-month-old control rats. Twenty-four hours after the last behavioral test, the rats were sacrificed and their brains were removed, dissected, and frozen in liquid nitrogen. The activities of MAO-A and MAO-B in the lateral cortex were determined. Results indicate that rats in the L-deprenyl group, the L-amphetamine group, and the young control group all learned the water maze task equally rapidly and significantly faster than rats in the saline group. MAO-A did not differ among the saline, amphetamine, and young control rats, but MAO-B was significantly higher in the middle aged saline and L-amphetamine rats than in the young controls. Both MAO-A and MAO-B activities were significantly lower in the L-deprenyl group than in the other three groups. This indicates that low-dose L-deprenyl can also inhibit MAO-A following chronic SC administration. Moreover, the improved cognitive performance produced by L-deprenyl may not be due to its ability to inhibit MAO-B, but rather to some other effect such as the activation of growth factors.(ABSTRACT TRUNCATED AT 250 WORDS)

Glutamate, beta-amyloid precursor proteins, and calcium mediated neurofibrillary degeneration

In this article we present evidence supporting the interaction between excitotoxicity, beta APP mismetabolism, metabolic compromise and intracellular calcium destabilization in the process of neurodegeneration associated with Alzheimer's disease (AD). AD is characterized by the presence of neurofibrillary tangles and amyloid-containing plaques in specific regions of the brain. There appear to be several processes which contribute to the neurodegeneration associated with AD. Although AD has been linked to genetic mutations on chromosomes 21, 19 and 14, there are sporadic forms of AD that have no known genetic mutation involved. Aging is the major risk factor for AD. During the course of normal aging several metabolic compromises may occur in the brain. Both decreased glucose transport and utilization, and increased glucocorticoid levels are known to occur with aging and may lead to decreased energy supplies, ATP depletion, failure of Ca2+ buffering systems, excess glutamate release and activation of glutamate receptors. In addition, a reduction in antioxidant enzymes and consequently an increase in free radicals has also been associated with aging. Each of the preceeding alterations would lead to an increase in neuronal [Ca2+]i. Elevated calcium could then activate calcium-dependent proteases which degrade particular cytoskeletal proteins, and lipases which generate free radicals resulting in membrane damage and possible cell death. In this article we provide evidence that amyloid beta-peptide (A beta), the substance which accumulates in AD plaques, exacerbates excitotoxic and metabolic compromises to neurons resulting in changes in the cytoskeleton which resemble those seen in the neurofibrillary tangles of AD. We also provide evidence that secreted forms of beta-amyloid precursor protein (beta APP) are neuroprotective against excitotoxic insults. Recent findings concerning the normal function of beta APP and the mechanism of A beta toxicity place beta APP at the center of changes leading to neuronal degeneration in AD.

Age-related memory decline and longevity under treatment with selegiline

The MAO-B inhibitor selegiline is used in the treatment of Parkinson's disease. Further, beneficial effects in Alzheimer's disease have also been described as well as neuroprotective effects, increased longevity and an attenuation of age-related cognitive decline in experiments using rats. Our studies in mice and Syrian hamsters aim at the question whether the effects of selegiline reported in the rat can be generalized to other species. Aged female NMRI-mice (23 mo.) treated with selegiline (0.25 mg/kg, i.p., 3 times a week for 2-3 weeks) showed no treatment effect in the Morris water maze and in passive avoidance learning after 2 and 3 weeks of treatment. However, Syrian hamsters chronically treated with selegiline (0.05 mg/kg/day in the food, starting at 12 months old) showed a 3 month delay in the age-related decline of spontaneous alteration behavior, a measure of longer-term memory, compared to untreated controls. Since treated hamsters also show increased longevity (study still in progress) the data suggest a protective effect of a chronic treatment with selegiline against age-related cognitive and physical decline.

Further proof that (-)deprenyl fails to facilitate mesolimbic dopaminergic activity

The selective monaminooxidase (MAO)-B inhibitor (-)deprenyl facilitates the nigrostriatal dopamine (DA)-ergic system by a complex mechanism that includes inhibition of DA reuptake and increase of DA turnover. In this study, DA reuptake and DA turnover were measured in the olfactory tubercle of rats treated with 0.25 mg/kg (-)deprenyl for 28 days. There was no difference between these rats and the saline-treated group. In another series of experiments, we analysed how (-)deprenyl influences the action of some indirectly acting DA agonists, such as amphetamine (AM) and phenylethylamine (PEA). The effect on different behavioural patterns related either to the nigrostriatal (stereotyped behaviour) or the mesolimbic (rearing, locomotion) DAergic system was investigated. As expected, the PEA-induced stereotyped behaviour was tremendously potentiated by (-)deprenyl and the AM-induced stereotypy was reduced. At the same time there was no change in locomotion and rearing. The results give further biochemical and behavioural proof that (-)deprenyl enhances the function of the nigrostriatal DAergic system and leaves the mesolimbic DAergic neurons unaffected.

L-deprenyl in the treatment of mild dementia of the Alzheimer type: results of a 15-month trial

OBJECTIVE

To examine the cognitive and behavioral effects of L-deprenyl in persons with mild dementia of the Alzheimer type (DAT) over a 15-month period.

DESIGN

A 15-month randomized, double-blind, placebo-controlled trial using a parallel-group design.

PARTICIPANTS

39 subjects with mild DAT (CDR 1) selected using NINCDS-ADRDA criteria.

OUTCOME MEASURES

A battery of neuropsychological tests and clinical rating scales.

RESULTS

The placebo and L-deprenyl subjects were similar at baseline on the clinical and neuropsychological tests. The total score on the Brief Psychiatric Rating Scale (BPRS) was significantly less after 15 months in subjects taking L-deprenyl. The only individual item of the BPRS which differed between groups was disorientation. There was no evidence of a L-deprenyl effect on any other clinical or neuropsychological measure after 2, 8, or 15 months.

CONCLUSION

L-deprenyl did appear to have a slight effect on a single measure of psychopathology, the BPRS. It did not have a measurable impact on any other measure of behavior or cognitive function over a 15-month period in this group of subjects with mild DAT and did not appear to slow the progression of the disease.

Cognitive impairment in schizophrenia: how experimental models using nonhuman primates may assist improved drug therapy for negative symptoms

Antipsychotic drugs provide effective relief from hallucinations but do not improve, and may even induce, other symptoms of schizophrenia. Tardive dyskinesia, which is often associated with intellectual impairment, is generally attributed to chronic therapy with antipsychotic drugs. However, the possible contribution of medication to cognitive impairment is not easily dissociated from the underlying progression of the disease. Recently evidence has accumulated from studies performed in patients and experimental monkeys that augmentation of catecholamine function may improve performance on certain cognitive tasks. Further investigation of the role of catecholamines in cognition is warranted in order to assist development of antipsychotic drugs with fewer undesirable effects and entirely new approaches to therapy for cognitive impairment in schizophrenia.

Effects of monoamine oxidase inhibition by selegiline on concentrations of noradrenaline and monoamine metabolites in CSF of patients with Alzheimer's disease

A double-blind, cross-over trial with 12 patients with Alzheimer's disease (AD) was carried out primarily to test the suitability of this design in the investigation of the clinical effects of selegiline (10 mg/day) in AD. Cerebrospinal fluid (CSF) samples for the determination of concentrations of noradrenaline (NA) and several monoamine metabolites were collected at baseline and at the end of both four-week treatment periods (placebo and selegiline). The severity of dementia was assessed using Ferm's and Gottfries-Bråne-Steen (GBS) dementia scales. The concentrations of the dopamine metabolite, 3,4-dihydroxyphenylacetic acid (DOPAC) and the NA metabolites, 3,4-dihydroxyphenylglycol (DHPG), and 3-methoxy-4-hydroxyphenyl glycol (MHPG) decreased significantly during selegiline treatment. There was a clear trend of reduction in concentrations of homovanillic acid (HVA) during selegiline treatment, whereas the concentrations of NA, 5-hydroxyindoleacetic acid (5-HIAA), and tryptophan did not differ significantly. The study design was not suitable for the analysis of the clinical results as there was a significant carry-over effect in both scales. As only the first period data could be used in the analysis, there were no significant differences in the scores of Ferm's or GBS scales, but clear positive trends could be detected in favour of selegiline.

The interaction of L-deprenyl and scopolamine on spatial learning/memory in rats

L-Deprenyl, a specific MAO-B inhibitor, has been reported to improve learning/memory in some cognitive tests in aged rats. The present study investigated whether L-deprenyl could alleviate the spatial learning deficit induced by muscarinic blockade and aging in OFA rats. Scopolamine (0.25 mg/kg) impaired the acquisition of a water maze task in adult rats and increased their swimming speeds. L-Deprenyl (0.25 mg/kg, 14 days) had no effect on water maze performance in saline treated adult rats, but markedly alleviated the learning deficit induced by scopolamine and increased the time and distance of swimming in the training quadrant when the platform was removed (spatial probe trial). L-Deprenyl partly reduced the effect of scopolamine on speed of swimming. Nevertheless, administration of l-deprenyl (0.25 mg/kg, 14 days) had no effect on spatial learning/memory in aged rats. We suggest that the l-deprenyl-scopolamine interaction in the water maze test may be considered as a premise for further investigations of l-deprenyl as cognition enhancer.

Chronic treatment of aged mice with L-deprenyl produces marked striatal MAO-B inhibition but no beneficial effects on survival, motor performance, or nigral lipofuscin accumulation

Male C57BL/6J mice were provided I-deprenyl (at 0, 0.5 mg/kg or 1.0 mg/kg per day) in their drinking water beginning at 18 months of age. A battery of motor tests, including open-field, tightrope, rotorod, inclined screen, runwheel, and rotodrum tests, was administered before treatment and then 6 months later at 24 months of age. A subsample of mice was retested again at 27 months of age. An untreated group of 9-month-old mice served as young controls. Deprenyl treatment reduced striatal MAO-B activity by up to 60% after 6 months on treatment but had no significant effects on striatal catecholamine levels. No significant effects of deprenyl treatment were observed on body weight, fluid intake, or survival of the mice. Chronic deprenyl treatment also did not affect motor performance in any test, except rotodrum performance at 27 months of age, which was significantly better in the 1.0 mg/kg group treated group compared to controls. No age or deprenyl effects were observed with respect to cell counts in the substantia nigra. However, nigral cells containing lipofuscin increased with age, but this neurohistochemical parameter was also unaffected by deprenyl treatment.

Effect of structural modification of alkyl N-propargylamines on the selective inhibition of monoamine oxidase B activity

A series of alkyl N-methyl-propargylamine derivatives has been discovered recently to be very potent selective irreversible monoamine oxidase B inhibitors (MAO-B). In the present study, we used a simple compound in this series, namely N-2-butyl-N-methylpropargylamine.HCl (2-BuMP), as the basic structure to investigate the effect of structural modification on the effectiveness and selectivity of the inhibition of MAO activities. When the N-methyl group was replaced by a hydrogen atom, an ethyl group or a propargyl group, MAO inhibitory activity was abolished. The modification of the propargyl group, e.g. to 3-butynyl, N-cyanomethyl or to allyl groups, also destroyed the inhibitory activity. The potency of the inhibitors was related to the carbon chain length of the alkyl group as well as to the substitution of the alpha or the terminal carbon atoms. Substitution of hydroxyl, carboxyl or carboethoxyl groups on the terminal carbon of the alkyl chain drastically reduced the inhibitory activity. More potent MAO inhibitory activity was observed for molecules with a single methyl group substitution on the alpha carbon in comparison with those substituted with two hydrogen or two methyl groups. Other branched alkyl N-methylpropargylamines, e.g. N-methyl-N-(3-pentyl)propargylamine, appeared to be slightly less selective in the inhibition of MAO-B activity. Some of these alkyl propargylamine MAO-B inhibitors, which do not possess the amphetamine-like moiety of L-deprenyl, may have significant neuropsychopharmacological implications.

Dopamine and depression

The dopamine hypothesis of schizophrenia and the emphasis on other neurotransmitters, most notably norepinephrine, serotonin, and acetylcholine, in the pathogenesis of depression, have focused attention away from substantial evidence implicating dopamine in affective disorders. The clinical evidence includes alterations in depressive symptoms with aging (concomitant with possible changes in dopamine metabolism), potential dopaminergic involvement in several subtypes of depression, similarities between some of the symptoms of Parkinson's disease and those of depression (including psychomotor retardation and diminished motivation), and potential dopaminergic abnormalities in seasonal mood disorder. The biochemical evidence in patients with depression derives from studies of homovanillic acid, a dopamine metabolite, indicating diminished dopamine turnover. In addition, there is a considerable amount of pharmacologic evidence regarding the efficacy of antidepressants with dopaminergic effects in the treatment of depression. We conclude that dopamine likely contributes significantly to the pathophysiology of depression. However, the role of dopamine in this syndrome must be understood in the context of existing theories involving other neurotransmitters which may act independently, and interact with dopamine and other neurochemicals, to contribute to depression.

Monoamine neurons in aging and Alzheimer's disease

The integrity of dopaminergic, noradrenergic and serotonergic neurons in normal aging and Alzheimer's disease is reviewed. Loss of dopaminergic innervation of the neostriatum is a prominent age-related change, which corresponds with the age-related loss of dopaminergic cell bodies from the substantia nigra. This change is regionally specific, since dopaminergic innervation of the neocortex and the neostriatum are not affected. Although there is an age-related loss of noradrenergic cell bodies from the locus coeruleus, most studies indicate normal concentrations of noradrenaline in target areas. There is also evidence for reduced serotonergic innervation of the neocortex and, less convincingly, the neostriatum. Alzheimer's disease is associated with more pronounced noradrenergic and serotonergic denervation but, unlike normal aging, dopaminergic innervation of neostriatum is intact; although dopamine neurons are probably dysfunctional in this region. Studies relating neuronal markers to the symptomatology of Alzheimer's disease indicate that dysfunction of monoamine neurons is more closely linked to non-cognitive than to cognitive changes in behavior. In addition, monoaminergic therapies have been successful in ameliorating affective and psychotic behaviors along with sleep disturbances in both Alzheimer's disease and senescence. It seems likely that monoaminergic therapies (developed as we learn more about alterations in dopamine, noradrenaline and serotonin) will continue to be necessary to treat such behavioral disturbances.

Determination of amphetamine, methamphetamine and desmethyldeprenyl in human plasma by gas chromatography/negative ion chemical ionization mass spectrometry

A sensitive and specific assay for the quantitative determination of amphetamine, methamphetamine and desmethyldeprenyl in human plasma specimens is described. Electron capture/negative ion chemical ionization gas chromatography/mass spectrometry is used to determine the extracted plasma concentrations of the three target compounds as their N-heptafluorobutyryl derivatives. Quantitation is performed by stable isotope dilution using d6-amphetamine and d6-methamphetamine as internal standards. Selected ion monitoring of the [M-HF]- ions of both the analytes and internal standards results in minimum quantifiable limits of 0.10 ng ml-1 for both amphetamine and methamphetamine and 0.25 ng ml-1 for desmethyldeprenyl. Excellent linearity (r = 0.998) up to at least 5.00 ng ml-1 is demonstrated.

L-deprenyl in the treatment of mild dementia of the Alzheimer type: preliminary results

OBJECTIVE

To examine the short-term cognitive and behavioral effects of L-deprenyl in persons with mild dementia of the Alzheimer type (DAT) over a 2-month period.

DESIGN

A 15-month randomized, double-blind, placebo-controlled trial using a parallel-group design. This report deals with the first 2 months of the trial.

PARTICIPANTS

39 subjects with mild DAT (CDR 1) selected using NINCDS-ADRDA criteria.

MEASURES

A battery of neuropsychological tests and clinical rating scales.

RESULTS

The placebo and L-deprenyl subjects were similar at baseline on the clinical and neuropsychological tests. There was no evidence of a L-deprenyl effect on any clinical or neuropsychological measures after 2 months.

CONCLUSION

L-deprenyl did not have a measurable impact on behavior or cognitive function over a 2-month period in this group of subjects with mild DAT.

Chronic effects of monoamine oxidase-B inhibitors on the behaviour of aged mice

In order to measure the chronic effects of monoamine oxidase-B (MAO-B) inhibitors on the physical and cognitive condition of 60 aged male mice, 1-deprenyl or N-methyl-N-(2-pentyl)-propargylamine (M-2-PP) were administered in drinking water (10 micrograms/ml/day) for 37 weeks. The spontaneous open-field locomotion, balancing ability and weight gain of the mice were assessed continuously. At the end of the study the spatial learning ability of all surviving mice was assessed in a Morris water maze. Both drug groups exhibited a reduction in spontaneous locomotion at the same rate as the control group, while there were no changes in balancing ability. The mice receiving 1-deprenyl, however, performed the water maze task less well than the control group. The mice receiving 1-deprenyl also gained weight at a significantly reduced rate compared to both the M-2-PP and water treated groups. A brain MAO assay indicated that MAO-B was completely inhibited by both drugs while MAO-A remained unchanged. The implications of these data on longevity studies using 1-deprenyl and other MAO-B inhibitors are discussed.

Changes in spontaneous behavior in the dog following oral administration of L-deprenyl

An open-field activity test was developed for studying the effect of a single oral dose (range of 0.1-5 mg/kg) of L-deprenyl on spontaneous behavior in the dog. A computer program was used to quantify observations of locomotor activity, directed sniffing, urination, grooming, inactivity, jumping, rearing, and vocalization during a 10-min baseline and posttreatment session. Three dose-dependent behavioral changes were observed: an overall decrease in directed sniffing, an increase in total locomotor activity in females, and a decrease in frequency of urination in males. These effects were only seen at the dose levels of 2 mg/kg or higher. Computer-assisted tracings of behavioral patterns showed increased stereotypical behavior and decreased exploratory behavior at the high-dose levels. These behavioral effects are most likely due to either increased levels of phenylethylamine resulting from inhibition of monoamine oxidase B and/or the production of amphetamines as a result of the metabolism of L-deprenyl.

Pharmacological basis of the therapeutic effect of (-)deprenyl in age-related neurological diseases

(-)Deprenyl (Selegiline, Jumex, Eldepryl, Movergan), a close structural relative to phenylethylamine (PEA), is a drug of a unique pharmacological spectrum. (a) It is highly potent and selective irreversible inhibitor of B-type monoamine oxidase (MAO), a predominantly glial enzyme in the brain, the activity of which significantly increases with age. (-)Deprenyl was the first selective inhibitor of MAO-B described in literature, became the worldwide research tool used for blocking selectively B-type MAO, and is still the only MAO-B inhibitor in clinical use. (b) (-)Deprenyl interferes with the uptake of catecholamines and indirectly acting sympathomimetics because it is handled by the catecholaminergic neuron similarly to the physiological substances transported through the axonal end-organ and vesicular membrane. The unique behavior of (-)deprenyl is that, in striking contrast to PEA and its relatives, it does not push the transmitter from the storage places, i.e., it is not a releaser. The net result is that (-)deprenyl inhibits the releasing effect of tyramine and is presently the only safe MAO inhibitor which can be administered without dietary restrictions. (c) Maintenance on (-)deprenyl enhances selectively superoxide dismutase (SOD) and catalase activity in the striatum. This effect is unrelated to the MAO and uptake inhibitory effects of the drug. (d) Maintenance on (-)deprenyl facilitates the activity of the nigrostriatal dopaminergic neurons with remarkable selectivity. This effect is also unrelated to either the MAO or the uptake inhibitory effects of the drug. All in all, (-)deprenyl maintains the activity of the nigrostriatal dopaminergic machinery on a higher activity level and slows down its age-related decline. Male rats maintained on (-)deprenyl lost their capacity to ejaculate later, retained their learning ability longer, and lived longer than their saline-treated peers. Parkinsonians on levodopa plus (-)deprenyl (10 mg daily) lived significantly longer than those on levodopa alone. (-)Deprenyl is the first drug which retards the progress of Parkinson's disease. Freshly diagnosed parkinsonians maintained on (-)deprenyl did not require levodopa until significantly later than their placebo-treated peers. Maintenance on (-)deprenyl significantly improved the performance of patients with Alzheimer's disease. It is concluded that in Parkinson's disease and Alzheimer's disease patients need to be treated daily with 10 mg (-)deprenyl from diagnosis until death, irrespective of other medication.(ABSTRACT TRUNCATED AT 400 WORDS)

(-)Deprenyl-medication: a strategy to modulate the age-related decline of the striatal dopaminergic system

(-)Deprenyl (Selegiline, Jumex, Eldepryl, Movergan), a close structural relative to phenylethylamine (PEA), is a drug with a unique pharmacological spectrum. (1) It is a highly potent and selective, irreversible inhibitor of B-type monoamine oxidase (MAO), a predominantly glial enzyme in the brain. The activity of this enzyme significantly increases with age. (-)Deprenyl, the first selective inhibitor of MAO-B described in literature, has become the universally used research tool for selectively blocking B-type MAO. It is the only MAO-B inhibitor in clinical use. (2) (-)Deprenyl interferes with the uptake of catecholamines and indirectly acting sympathomimetics because it is handled by the catecholaminergic neuron in a way similar to the physiological substances transported through the axonal end organ and vesicular membrane. The unique behavior of (-)deprenyl is that, in striking contrast to PEA and its relatives, it does not displace the transmitter from storage, ie, it is not a releaser. The net result is that (-)deprenyl inhibits the releasing effect of tyramine, and, at present, is the only safe MAO inhibitor that can be administered without dietary precautions. (3) Maintenance on (-)deprenyl selectively enhances superoxide dismutase (SOD) and catalase activity in the striatum. This effect is unrelated to its effect on MAO-B and the inhibitory effects of the drug on neurotransmitter uptake. (4) Maintenance on (-)deprenyl facilitates the activity of the nigrostriatal dopaminergic neurons with remarkable selectivity, and this effect, too, is unrelated to either its effects on MAO or on neurotransmitter uptake. (5) Maintenance on (-)deprenyl prevents the characteristic age-related morphological changes in the neuromelanin granules of the neurocytes in the substantia nigra. All in all, (-)deprenyl increases the activity of the nigrostriatal dopaminergic system and slows its age-related decline. Maintenance of male rats on (-)deprenyl delays the loss of the capacity to ejaculate, slows the decline of learning and memory, and significantly lengthens the life-span as compared with saline-treated rats. Parkinson's disease patients on levodopa plus (-)deprenyl (10 mg daily) live significantly longer than those on levodopa alone. (-)Deprenyl is the first drug that retards the progress of Parkinson's disease. Newly diagnosed Parkinson's disease patients maintained on (-)deprenyl need levodopa significantly later than their placebo-treated peers. Maintenance on (-)deprenyl improves significantly the performance of patients with Alzheimer's disease. It is concluded that Parkinson's disease and Alzheimer's disease patients need to be treated daily with 10 mg (-)deprenyl from diagnosis until death, irrespective of other medication.(ABSTRACT TRUNCATED AT 400 WORDS)

The pharmacological profile of (-)deprenyl (selegiline) and its relevance for humans: a personal view

(-)Deprenyl (selegiline, jumex, eldepryl, movergan) which is closely related to phenylethylamine (PEA) is a drug with a unique pharmacological spectrum. Single dose effects: (a) It is a highly potent and selective inhibitor of B-type monoamine oxidase (MAO). (b) In contrast to other MAO inhibitors it inhibits the noradrenaline releasing effect of tyramine, is therefore free of the 'cheese effect'. Multiple dose effects unrelated to MAO inhibition: (a) It enhances superoxide dismutase and catalase activity in the striatum. (b) It facilitates the activity of the nigrostriatal dopaminergic neurones. (c) It prevents age-related morphological changes in the neurocytes of the substantia nigra. Consequences of multiple dose effects: Compared to salt solution-treated rats, male rats maintained on (-)deprenyl loose their capacity to ejaculate later on; retain for longer their learning ability; and live longer. Freshly diagnosed Parkinson's patients maintained on (-)deprenyl, required levodopa later than their placebo-treated peers. Patients treated with levodopa plus (-)deprenyl live longer than those on levodopa alone. Chronic treatment with (-)deprenyl improves the performance of patients with Alzheimer's disease.