Assessment of selegiline and trilostane combined therapy efficacy for canine pituitary-dependent hypercortisolism treatment: A pilot randomized clinical trial.

Canine pituitary-dependent hypercortisolism (PDH) management with trilostane usually demands lifelong therapy. The greater the dose needed, the greater the risk of side effects. Selegiline therapy has been previously described but not commonly used for PDH treatment. The present work aimed to assess the efficacy of selegiline and trilostane combined therapy for canine PDH treatment. Fifteen client-owned dogs diagnosed with spontaneous PDH were enrolled. The patients were treated with trilostane (Tri group, n = 8, initial dose of 0.5 mg/kg, PO, q12h), or with trilostane and selegiline (Tri + Sel group, n = 7, initial trilostane dose of 0.5 mg/kg, PO, q12h and selegiline 1 mg/kg, PO, q24h). Dogs underwent clinical examination, serum biochemical analysis, urinalysis, abdominal ultrasound, and eACTH and post-ACTH cortisol measurements on treatment days zero (D0), 30 (D30), 90 (D90), and 180 (D180). There was a lack of adverse effects due to the combined therapy. Both groups showed a similar clinical response and lower post-ACTH cortisol levels at the study's end. There was no significant difference in trilostane dosage at D180 between groups. There was no documented increase in either right or left adrenal gland thickness in the Tri + Sel group in contrast with patients in the Tri group. However, there was no statistical difference between the groups regarding eACTH at D0 and D180. Patients in the Tri + Sel group achieved better serum triglycerides control at the end of the study. The association of selegiline with trilostane might be a feasible therapy for canine PDH; however, its eventual advantages need larger studies.

Immobilization of Amano lipase AK from Pseudomonas fluorescens on different types of chitosan-containing supports: use in the kinetic resolution of rac-indanol.

Amano lipase AK from P. fluorescens was immobilized on different types of chitosan-containing supports. Chitosan lower molecular weight (2.5%), chitosan lower molecular weight/sodium alginate (2.5%/2.5%) and chitosan lower molecular weight/carrageenan (2.5%/2.5%) allowed the highest values of immobilization yields (IY) of 81, 81 and 83%, respectively. Best activity results were achieved using chitosan average molecular weight (5%) and chitosan lower molecular weight/sodium alginate (2.5%/2.5%) as support, with values of 1.40 and 1.30 UpNPB/ggel and with recovery activities of 45.75 and 35.6%, respectively. These derivatives were evaluated in the kinetic resolution of rac-indanol to obtain a key intermediate in the synthesis of a drug used in the treatment of Parkinson's disease. The most efficient derivatives in the kinetic resolution were lipase immobilized on chitosan average molecular weight (5.0%) and chitosan low molecular weight/sodium alginate, the latter leading to obtaining both (S)-indanol and (R)-indanyl acetate with > 99% ee and 50% conversion.

Influence of DRD1 and DRD3 Polymorphisms in the Occurrence of Motor Effects in Patients with Sporadic Parkinson's Disease.

Parkinson's disease (PD) is a multisystem disorder that affects 2-3% of the population ≥ 65 years of age. The main pharmacologic agent use in the treatment of clinical symptoms of PD is levodopa (L-DOPA). However, the chronic use of L-DOPA might result in the emergence of motor complications such as motor fluctuation and dyskinesia. Previous studies have shown that the inter-individual variability and pharmacogenetic profile of PD patients seem to influence the occurrence of motor complications. For these reasons, the purpose of this study was to evaluate a possible relationship between DRD1 A48G and DRD3 Ser9Gly genetic variants with the occurrence of motor complications in PD patients in a Brazilian population. A total of 228 patients with idiopathic PD were enrolled. Patients were genotyped for DRD1 A48G and DRD3 Ser9Gly polymorphisms using PCR-RFLP. The univariate and multivariate analyses were performed to assess the association of these polymorphisms with the occurrence of motor fluctuation and dyskinesia in PD patients. Multiple Poisson regression analyses showed a protector effect to the occurrence of dyskinesia for individuals carrying of the DRD1 G/G genotype (PR 0.294; CI 0.09-0.87; p ≤ 0.020) after the threshold Bonferroni's. Besides, we verified risk increased to the occurrence of motor complications with daily L-DOPA dosage, disease duration, and users of rasagiline, selegiline, or entacapone (p < 0.05 for all). Our results suggest that the DRD1 A48G polymorphism and the presence of extrinsic and intrinsic factors may role an effect in the occurrence of dyskinesia in PD patients.

Zebrafish (Danio rerio) water tank model for the investigation of drug metabolism: Progress, outlook, and challenges.

Zebrafish (Danio rerio) water tank (ZWT) approach was investigated as an alternative model for metabolism studies based on six different experiments with four model compounds. Sibutramine was applied for the multivariate optimization of ZWT conditions, also for the comparison of the metabolism among ZWT, humans and mice, beyond for the role of CYP2B6 in ZWT. After the optimization, 18 fish and 168 hours of experiments is the minimum requirement for a relevant panel of biotransformation products. A comparison among the species resulted in the observation of the same hydroxylated metabolites, with differences in metabolites concentration ratio. However, the ZWT allowed tuning of the conditions to obtain a specific metabolic profile, depending on the need. In addition, by utilizing CYP2B6 inhibition, a relevant ZWT pathway for the demethylation of drugs was determined. The stereospecificity of the ZWT metabolism was investigated using selegiline and no racemization or inversion transformations were observed. Moreover, the investigation of metabolism of cannabimimetics was performed using JWH-073 and the metabolites observed are the same described for humans, except for the hydroxylation at the indol group, which was explained by the absence of CYP2C9 orthologs in zebrafish. Finally, hexarelin was used as a model to evaluate studies by ZWT for drugs with low stability. As a result, hexarelin displays a very fast metabolization in ZWT conditions and all the metabolites described for human were observed in ZWT. Therefore, the appropriate conditions, merits, and relevant limitations to conduct ZWT experiments for the investigation of drug metabolism are described.

Comparative In Vitro Study of 11C-Methionine and 11C-Deuterodeprenyl Uptake in Three Human Glioma Cell Lines.

AIM: To compare the uptake of 11C-deuterodeprenyl (11C-DED) and 11C-methionine (11C-MET) in three human glioma cell lines and study the relationship with glial fibrillary acid protein (GFAP) and monoamine oxidase B (MAO B) expression. 11C-DED is used in positron emission tomography imaging as a marker of astrocytosis in various central nervous system pathologies. It binds irreversibly to MAO B, a glial dimeric enzyme with increased activity in some neurological pathologies. MATERIALS AND METHODS: Binding and internalization studies of 11C-MET and 11C-DED were performed in astrocytoma grade III, glioblastoma grade IV, and radio-resistant glioblastoma grade IV cells. Immunofluorescence was used. RESULTS: 11C-MET specific activity bound to membrane was 9.0%-11.1% and that internalized was 88.9%-91.0%. 11C-DED specific activity bound to membrane was 34.8%-58.0% and that internalized was 38.7%-65.2%. Immunocytochemistry revealed GFAP and MAO B expression. CONCLUSIONS: The expression of MAO B measured by 11C-DED uptake or immunocytochemistry was not significantly different in grade III or IV cells. The GFAP signal was higher for grade IV compared to grade III. 11C-MET uptake was high in all the tumor cells. 11C-DED is a dopamine analogue and the transport across cell membranes is expected to be mediated by DAT receptors present in astrocytes. Reactive astrocytes surround tumor lesions; so the authors suggest that the 11C-DED uptake might be caused by the reactive astrocytosis and not by MAO B expression in tumor cells.

Automated radiosynthesis of [(11)C]L-deprenyl-D2 and [(11)C]D-deprenyl using a commercial platform.

Two (11)C-labelled PET tracers, (R)-N-[(11)C]methyl-N-(3,3-dideuteropropargyl)-1-phenylpropan-2-amine ([(11)C]L-deprenyl-D2, [(11)C]DED) and (S)-N-[(11)C]methyl-N-propargyl-1-phenylpropan-2-amine ([(11)C]D-deprenyl, [(11)C]DDE) were synthesised. One step N-alkylation with [(11)C]MeI or [(11)C]MeOTf was performed using the automated platform TRACERlab® FX-C Pro. The labelled products were obtained with (37±15)% (n=10) (end of synthesis, decay corrected from [(11)C]MeI) radiochemical yields from [(11)C]MeI after 38±3min synthesis time. In all cases, radiochemical purity was over 99% when [(11)C]MeOTf was used. This synthesis using a commercial platform makes these tracers more accessible for clinical research purposes.

Antidepressant-like effect of Ilex paraguariensis in rats.

In this study, we investigated the possible antidepressant-like effect of I. paraguariensis in rats. Rats were treated for four weeks with an aqueous extract of I. paraguariensis in drinking water, following the traditional preparation of this beverage. After the period of treatment, behavioral (elevated plus-maze, open field test, and forced swimming test) and biochemical parameters (lipid peroxidation assay, thiol content, vitamin C levels, and monoamine oxidase activity) were evaluated. Animals were also analyzed on forced swimming test after 24 hours of I. paraguariensis intake. An additional group was injected with selegiline 24 hours and 30 minutes before forced swimming test as positive control. HPLC analysis revealed the profile of I. paraguariensis extract. I. paraguariensis reduced the immobility time on forced swimming test without significant changes in locomotor activity in the open field test. Any anxiolytic/anxiogenic effect of I. paraguariensis was observed in rats through the elevated plus-maze test. The antidepressant-like effect of I. paraguariensis was not accompanied by inhibitory effect on monoamine oxidase activity. There were no significant alterations on lipid peroxidation, thiol content, and vitamin C levels among the groups. In conclusion, aqueous extract of I. paraguariensis decreases the time of immobility in rats suggesting an antidepressant-like effect.

Fabrication and in vitro characterization of polymeric nanoparticles for Parkinson's therapy: a novel approach

The objective of the research was to formulate and evaluate selegiline hydrochloride loaded chitosan nanoparticles for the Parkinson's therapy in order to improve its therapeutic effect and reducing dosing frequency. Taguchi method of design of experiments (L9 orthogonal array) was used to get optimized formulation. The selegiline hydrochloride loaded chitosan nanoparticles (SHPs) were prepared by ionic gelation of chitosan with tripolyphosphate anions (TPP) and tween 80 as surfactant. The SHPs had a mean size of (303.39 ± 2.01) nm, a zeta potential of +32.50mV, and entrapment efficiency of SHPs was 86.200 ± 1.38%. The in vitro drug release of SHPs was evaluated in phosphate buffer saline (pH 5.5) using goat nasal mucosa and found to be 82.529% ± 1.308 up to 28 h. Release kinetics studies showed that the release of drug from nanoparticles was anomalous (non-fickian) diffusion indicating the drug release is controlled by more than one process i.e. superposition of both phenomenon, the diffusion controlled as well as swelling controlled release. SHPs showed good stability results as found during stability studies at different temperatures as mentioned in ICH guidelines. The results revealed that selegiline hydrochloride loaded chitosan nanoparticles are most suitable mode of delivery of drug for promising therapeutic action.

O objetivo da pesquisa foi formular e avaliar nanopartículas de quitosana contendo cloridrato de selegilina para terapia do Parkinson, a fim de melhorar o seu efeito terapêutico e reduzir a frequência de dosagem. Método de Taguchi, de planejamento experimental, (L9 matriz ortogonal) foi usado para obter a formulação otimizada. As nanopartículas de quitosana contendo cloridrato de selegilina (PCHs) foram preparadas por gelificação iônica de quitosana com ânions tripolifosfato (TPP) e Tween 80 como tensoativo. As PCHs apresentaram tamanho médio de (303.39 ± 2,01) nm, potencial zeta de +32.50 mV e eficiência de encapsulação de 86.200±1,38%. A liberação do fármaco in vitro foi avaliada em solução salina de tampão fosfato (pH 5,5), usando a mucosa nasal de cabra e o resultado encontrado foi de 82.529% ± 1.308, acima de 28 h. Estudos de cinética de liberação mostraram que a liberação do fármaco das nanopartículas foi por difusão anômala (não fickiana), indicando que é controlada por mais de um processo, ou seja, a superposição dos fenômenos de difusão controlada e intumescimento. As PCHs mostraram resultados de boa estabilidade, encontrada durante os estudos de estabilidade em temperaturas diferentes, como mencionado em diretrizes do ICH. Os resultados revelaram que o sistema de nanopartículas de quitosana contendo cloridrato de selegilina é o mais adequado sistema de liberação de fármacos de ação terapêutica promissora.

Selegiline reverses aß25₋35-induced cognitive deficit in male mice.

Alzheimer's disease (AD) is biochemically characterized by the occurrence of extracellular deposits of amyloid beta peptide (Aß) and intracellular deposits of the hyperphosphorylated tau protein, which are causally related to the pathological hallmarks senile plaques and neurofibrillary tangles. Monoamine oxidase B (MAO-B) activity, involved in the oxidation of biogenic monoamines, is particularly high around the senile plaques and increased in AD patients in middle to late clinical stages of the disease. Selegiline is a selective and irreversible MAO-B inhibitor and, although clinical trials already shown the beneficial effect of selegiline on cognition of AD patients, its mechanism of action remains to be elucidated. Therefore, we first investigated whether selegiline reverses the impairment of object recognition memory induced by Aß25-35 in mice, an established model of AD. In addition, we investigated whether selegiline alters MAO-B and MAO-A activities in the hippocampus, perirhinal and remaining cerebral cortices of Aß25-35-injected male mice. Acute (1 and 10 mg/kg, p.o., immediately post-training) and subchronic (10 mg/kg, p.o., seven days after Aß25-35 injection and immediately post-training) administration of selegiline reversed the cognitive impairment induced by Aß25-35 (3 nmol, i.c.v.). Acute administration of selegiline (1 mg/kg, p.o.) in combination with Aß25-35 (3 nmol) decreased MAO-B activity in the perirhinal and remaining cerebral cortices. Acute administration of selegiline (10 mg/kg, p.o.) decreased MAO-B activity in hippocampus, perirhinal and remaining cerebral cortices, regardless of Aß25-35 or Aß35-25 treatment. MAO-A activity was not altered by selegiline or Aß25-35. In summary, the current findings further support a role for cortical monoaminergic transmission in the cognitive deficits observed in AD.

Selegiline (deprenyl) decreases calbindin-D28k expression in cortical neurons of rats socially deprived during the post-weaning period.

Preclinical studies indicate that selegiline (deprenyl), frequently used in some neurodegenerative diseases, exert protective effects on central nervous system neurons of individuals exposed to social isolation (SI). Furthermore, it has been suggested that SI produces neuronal dysfunction due in part to an excessive intracellular Ca(2+) overload. Since the main intracellular Ca(2+) buffering mechanism involves changes in the calcium-binding protein calbindin-D28k (CB), and that CB neuronal expression can increase in response to Ca(2+) transients, we hypothesized that chronic selegiline administration in early socially isolated animals could minimize cell CB expression as an indirect indicator of protective mechanism against Ca(2+) overload. In the present study male rats were weaned at postnatal day 21 (P21) and randomly assigned to social deprivation (SI) or control (SC) environments for 30 days (P21-51). SI animals were further subdivided in two experimental groups: socially deprived-saline (SI-SAL) and socially isolated-selegiline (SI-SEL) for additional 30 days (P52-82). Medial frontal CB immunoreactivity (CB-ir) neurons were quantitatively and qualitatively analyzed. The results obtained indicate that neocortical cells of adult rats submitted to early SI show a significant increase in the number of CB-ir neurons per cortical field, while selegiline treatment significantly reduces this parameter.

Involvement of monoamine oxidase B on models of postoperative and neuropathic pain in mice.

In this study we assessed the involvement of monoamine oxidase B (MAO-B), a key enzyme implicated in monoamine metabolism, on postoperative (plantar incision) and neuropathic (partial sciatic nerve ligation) pain models in mice. Paw incision submitted mice showed a significant decrease in mechanical threshold compared with the sham-operated mice, characterizing the development of mechanical allodynia. The selective and irreversible MAO-B inhibitor selegiline, at a dose sufficient to selectively inhibit MAO-B activity (10 mg/kg), showed an anti-allodynic effect from 0.5 to 6 h after incision. Likewise, partial sciatic nerve ligation submitted mice also developed mechanical allodynia, which was reversed by selegiline (10 mg/kg) from 2 to 6 h after treatment. In addition, a significant increase on striatal MAO-B activity was observed in neuropathic mice compared with the sham-operated animals, which was reversed by selegiline treatment. Taken together, our results showed that MAO-B seems to exert a critical role in the development of postoperative and neuropathic pain.

The anti-Parkinsonian drug selegiline delays the nucleation phase of α-synuclein aggregation leading to the formation of nontoxic species.

Parkinson's disease (PD) is a movement disorder characterized by the loss of dopaminergic neurons in the substantia nigra and the formation of intraneuronal inclusions called Lewy bodies, which are composed mainly of α-synuclein (α-syn). Selegiline (Sel) is a noncompetitive monoamino oxidase B inhibitor that has neuroprotective effects and has been administered to PD patients as monotherapy or in combination with l-dopa. Besides its known effect of increasing the level of dopamine (DA) by monoamino oxidase B inhibition, Sel induces other effects that contribute to its action against PD. We evaluated the effects of Sel on the in vitro aggregation of A30P and wild-type α-syn. Sel delays fibril formation by extending the lag phase of aggregation. In the presence of Sel, electron microscopy reveals amorphous heterogeneous aggregates, including large annular species, which are innocuous to a primary culture enriched in dopaminergic neurons, while their age-matched counterparts are toxic. The inhibitory effect displayed by Sel is abolished when seeds (small fibril pieces) are added to the aggregation reaction, reinforcing the hypothesis that Sel interferes with early nuclei formation and, to a lesser extent, with fibril elongation. NMR experiments indicate that Sel does not interact with monomeric α-syn. Interestingly, when added in combination with DA (which favors the formation of toxic protofibrils), Sel overrides the inhibitory effect of DA and favors fibrillation. Additionally, Sel blocks the formation of smaller toxic aggregates by perturbing DA-dependent fibril disaggregation. These effects might be beneficial for PD patients, since the sequestration of protofibrils into fibrils or the inhibition of fibril dissociation could alleviate the toxic effects of protofibrils on dopaminergic neurons. In nondopaminergic neurons, Sel might slow the fibrillation, giving rise to the formation of large nontoxic aggregates.

Manganese neurotoxic time course is not influenced by L-deprenyl systemic treatment: influence of L-deprenyl in manganese neurotoxic time course.

Unilateral microinjection of manganese into the rat substantia nigra pars compacta (SNpc) leads to the death of nigral neurons and a decrease in dopamine (DA) within the ipsilateral striatum. L-deprenyl, an irreversible inhibitor of monoamine oxidase B, appears to protect or rescue dopaminergic nigral neurons from the toxic effects of 6-hydroxydopamine (6-OHDA) and 1-methyl-4 phenyl-1, 2, 3, 6-tetrahydropiridine (MPTP). In this study we aimed to investigate whether L-deprenyl is able to influence the manganese neurotoxic time course. L-deprenyl rescue activity was evaluated in discontinuous posology and its protective effect was evaluated in a continuous one. Apomorphine-induced rotational behavior and striatal tyrosine hydroxylase immunostaining (TH-IS) were evaluated in both conditions at 24 h, 72 h and 168 h after intranigral microinjections. Our results indicate a failure in L-deprenyl to influence the establishment and time course of rotational response to apomorphine. Strikingly, a further decrease in the tyrosine hydroxylase immunostaining, at 168 h post microinjection in L-deprenyl-treated rats was obtained. Our data revealed no correlation between an increasing rotational behavior and reduction in TH-IS.

Antioxidant effects of selegiline in oxidative stress induced by iron neonatal treatment in rats.

Increased levels of iron in specific brain regions have been reported in neurodegenerative disorders. It has been postulated that iron exerts its deleterious effects on the nervous system by inducing oxidative damage. In a previous study, we have shown that iron administered during a particular period of the neonatal life induces oxidative damage in brain regions in adult rats. The aim of the present study was to evaluate the possible protective effect of selegiline, a monoamino-oxidase B (MAO-B) inhibitor used in pharmacotherapy of Parkinson's disease, against iron-induced oxidative stress in the brain. Results have shown that selegiline (1.0 and 10.0 mg/kg), when administered early in life was able to protect the substantia nigra as well as the hippocampus against iron-induced oxidative stress, without affecting striatum. When selegiline (10.0 mg/kg) was administered in the adult life to iron-treated rats, oxidative stress was reduced only in the substantia nigra.

Chronic (-)-deprenyl administration attenuates dendritic developmental impairment induced by early social isolation in the rat.

It has been demonstrated that postweaning social isolation alters dendritic development in the medial prefrontal cortex (mPFC) of the rat. In addition, (-)-deprenyl, a monoamine oxidase B (MAO-B) inhibitor, promotes dendritic growth in prefrontocortical pyramidal cells. This study examined whether prefrontocortical dendritic developmental impairment induced by postweaning social isolation is attenuated by chronic (-)-deprenyl administration. Weanling Sprague-Dawley male rats were randomly reared in social and isolated environments between postnatal days 21 and 51 (P21-P51). At P52, half of the animals were behaviorally evaluated in the open-field test and sacrificed for histological analysis. The remaining isolated rats were subdivided into saline- and daily (-)-deprenyl-treated animals for 30 additional days (P52-P82). Socially-reared rats remained undisturbed except for daily saline administration. At P82, all animals were behaviorally evaluated and sacrificed for histological analysis. Dendritic quantification of the Golgi-Cox-Sholl-stained neurons indicated that chronic (-)-deprenyl administration partially compensated the dendritic growth impairment induced by social isolation. In addition, both isolated-saline- and (-)-deprenyl-treated rats showed a sustained locomotor hyperactivity in the open-field test.

Improvement of mouse brain mitochondrial function after deprenyl treatment.

Deprenyl is a selective monoamine oxidase (MAO) B inhibitor, widely used for treatment of Parkinson's disease. The present study shows that deprenyl treatment was able to improve mitochondrial function. Fourteen month old mice were injected i.p. with deprenyl (20 mg/kg) and killed 1.5 h after the administration. Different brain subcellular fractions were isolated from control and deprenyl-treated animals to evaluate the effect of deprenyl on nitric oxide synthase (NOS) activity. Oxygen consumption, hydrogen peroxide (H(2)O(2)) production, mitochondrial membrane potential and calcium-induced permeability transition (MPT) were studied in intact mitochondria. In addition, the effect of deprenyl on respiratory complexes and MAO activities were evaluated in submitochondrial particles (SMP). Monoamine oxidase activity was found to be decreased by 55% in mitochondria from deprenyl-treated animals and as a consequence, H(2)O(2) production was significantly decreased. Deprenyl inhibited NOS activity in cytosolic fractions and SMP by 40% and 55%, respectively. In similar conditions, SMP from deprenyl-treated animals showed increased cytochrome oxidase activity. A 51% increase in the oxygen uptake in state 3 (active respiration state) was found after deprenyl treatment, but no significant changes were observed in state 4 (resting respiration state). Deprenyl treatment protected against calcium-induced depolarization and was able to inhibit calcium-induced MPT. This work provides evidence that deprenyl treatment exerts an improvement of brain mitochondrial function, through a reduction of free radical production, prevention of calcium-induced MPT and maintaining a mitochondrial transmembrane potential.

Treatment of primary progressive freezing of gait with high doses of selegiline.

We report the case of a 76-year-old, right-handed woman with progressive primary freezing of gait. Despite several therapeutic strategies, she continued to worsen to the point that she became confined to a wheelchair. Treatment with selegiline in doses up to 20 mg/d led to marked improvement of the gait disorder. This case illustrates that selegiline can be an option for patients with freezing of gait other than those with Parkinson's disease.

Modulation of brain mitochondrial function by deprenyl.

The present study shows that deprenyl, a known inhibitor of monoamine oxidase B (MAO B), may generate changes in mitochondrial function. Brain submitochondrial membranes (SMP), synaptosomes and cytosolic fractions were incubated with different deprenyl concentrations and nitric oxide synthase (NOS) activity was measured. The effect of deprenyl on oxygen consumption, calcium-induced permeability transition and hydrogen peroxide (H(2)O(2)) production rates was studied in intact mitochondria. Respiratory complexes and monoamine oxidase activities were also measured in submitochondrial membranes. Incubation of brain submitochondrial membranes with deprenyl 10, 25 and 50 microM inhibited nitric oxide synthase activity in a concentration-dependent manner. The same effect was observed in cytosolic fractions and synaptosomes. Monoamine oxidase activity was inhibited at lower deprenyl concentrations (from 0.5 microM). Cytochrome oxidase (complex IV) activity was found 42% increased in the presence of 25 microM deprenyl in a condition of maximal nitric oxide synthase activity. Incubation of brain mitochondria with deprenyl 25 microM produced a 60% increase in oxygen uptake in state 3, but no significant changes were observed in state 4. Pre-incubation of brain mitochondria with deprenyl 0.5 and 1 microM inhibited calcium-induced mitochondrial permeability transition and decreased hydrogen peroxide production rates. Our results suggest that in vitro effects of deprenyl on mitochondrial function can occur through two different mechanisms, involving nitric oxide synthase inhibition and decreased hydrogen peroxide production.

Selegiline protects against recognition memory impairment induced by neonatal iron treatment.

Excess of iron in the brain has been implicated in the pathogenesis of several human neurodegenerative diseases, for example Alzheimer's disease and Parkinson's disease. It has been shown that the neonatal period is critical for the establishment of normal iron content in the adult brain. Moreover, it is known that aging alters the cerebral distribution of this metal. We have recently described that neonatal administration of iron severely impaired novel object recognition memory in rats. The aim of the present study was to determine whether selegiline, a monoamine oxidase (MAO) inhibitor known for its neuroprotective properties, could protect rats against cognitive impairment induced by neonatal administration of iron. In the first experiment, male Wistar rats received vehicle (5% sorbitol in water) or iron (10.0 mg/kg) orally from postnatal days 12 to 14 and saline (0.9% NaCl) or selegiline (1.0 or 10.0 mg/kg) intraperitoneally for 21 days, starting 24 h before the first iron dosing. In the second experiment, rats were given either vehicle or iron (10.0 mg/kg) orally from postnatal days 12 to 14 followed by saline or selegiline (1.0 or 10.0 mg/kg) intraperitoneally for 21 days, starting when rats reached adulthood (50th day after birth). Iron-treated rats given selegiline in both doses showed no deficits in recognition memory. Rats receiving iron but no selegiline presented memory deficits. This is the first study reporting the reversion of iron-induced memory impairment, supporting the view that our model can be considered as a useful tool in the search for new drugs with neuroprotective and/or memory enhancing properties.

LED fluorescence spectroscopy for direct determination of monoamine oxidase B inactivation.

In this work, we report an alternative assay for the determination of the inhibitory effect on monoamine oxidase B (MAO-B) activity of probe compounds. Enzyme MAO-B exhibits fluorescence emissions when it is excited at 412 nm. Using an inexpensive blue LED-like excitation source, we measured the quenching of fluorescence intensity of MAO-B enzyme during the reaction with inhibitors. The applicability of the procedure is demonstrated by assays with l-deprenyl and berberine as inhibitors through the use of fluorescence studies. The IC(50) values of l-deprenyl and berberine were 0.04 and 90 microM, respectively. The K(I) values were 0.020 and 47 microM for l-deprenyl and berberine, respectively. These IC(50) and K(I) values were similar to the values obtained with a standard method. These results demonstrate the feasibility of this method as an alternative to follow the inhibitory effect on MAO-B.