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In the last decade, several neuroprotective therapies have been proposed for Parkinson's disease and rasagiline was indicated as one of the most promising candidates by preclinical studies. The drug has already been tested in phase III clinical studies (the ADAGIO study). The mechanism underlying rasagiline-dependent neuroprotection is complex and almost unknown. Here, we show that rasagiline is involved in the regulation of the molecular composition of the postsynaptic density of glutamatergic synapses. In hippocampus as well as in striatum, rasagiline induces a significant reduction of synaptic levels of NR2A-containing NMDA receptors and in hippocampal slices it also significantly decreases synaptic levels of GluR1-containing AMPA receptors. This capability of rasagiline to modulate ionotropic glutamate receptors composition at synaptic sites strengthens the rationale for its clinical use to slow the progression of Parkinson's disease.

Alzheimer Disease is the most common chronic neurodegenerative disorder associated with aging. Nevertheless, its pharmacological therapy is still an unresolved issue. In double-blind controlled studies, acetyl-L-carnitine (ALC) demonstrated beneficial effects on Alzheimer's disease. However, the mechanisms behind its neuroprotective ability remain to be fully established. In this study, the effect of acetyl-L-carnitine on amyloid precursor protein (APP) metabolism was investigated by in vitro models, both in a neuroblastoma cell line and in primary hippocampal cultures. We found that ALC treatment stimulates alpha-secretase activity and physiological APP metabolism. In particular, ALC favors the delivery of ADAM10 (a disintegrin and metalloproteinase 10, the most accredited candidate for alpha-secretase) to the post-synaptic compartment, and consequently positively modulates its enzymatic activity towards APP. Our findings suggest that the benefits of ALC reported in previous clinical studies are underscored by the specific biological mechanism of this compound on APP metabolism. In fact, ALC can directly influence the primary event in Alzheimer's disease pathogenesis, i.e. the Amyloid beta cascade, promoting alpha-secretase activity and directly affecting the release of the non amyloidogenic metabolite.

We found that pergolide, a dopamine D1/D2 receptor agonist used in the clinical therapy of Parkinson's disease, protects SH-SY5Y neuroblastoma cells from cell death induced by a brief pulse (15 min) of 1 mM H(2)O(2). Neuroprotection was found when pergolide was added to the culture medium either simultaneously with (EC(50)=60 nM) or 2 h before (EC(50)=40 nM) H(2)O(2) treatment. These effects were not blocked by different dopamine receptor antagonists. Our data suggest that pergolide, independently of dopamine receptor stimulation, may interfere with the early phases of the oxidative stress-induced neurotoxic process.

The aim of this study was to evaluate the possible effects of nicergoline, a semisynthetic ergot derivative, on the biochemical changes observed during chronic treatment with haloperidol in male Sprague-Dawley rats. Chronic treatment with haloperidol induced a significant decrease in the cellular glutathione (GSH) content in selected areas of the brain (cerebellum, striatum and cortex) and in the liver. Prolonged nicergoline administration was able to antagonize the haloperidol-induced GSH decrease, maintaining the GSH concentration at levels comparable to those observed in the control group. Analysis of the energy charge revealed changes similar to those observed for GSH: haloperidol induced a significant decrease in ATP and energy charge that was completely reversed by repeated nicergoline administration. In conclusion, chronic treatment with the classical antipsychotic haloperidol induces profound biochemical changes in the brain and in the liver. Nicergoline treatment is able to counteract the haloperidol-induced decrease in GSH levels and energy charge, suggesting a potential role of the drug in the treatment of neuroleptic-induced side effects.

The aim of the present observational study was to assess the value of the C825T polymorphism of the β-3 subunit of G proteins (GNB3) as well as of variants in the SLC6A4 gene (5HTTLPR and STin2 VNTR) and DRD2 gene (TaqI A and NcoI) as predictive markers for consistency in headache response to triptans in migraine patients. Consistent responders to triptans were defined as the migraineurs who experienced a ≥ 2 point reduction in a 4-point scale intensity of pain from 3 (severe) to 0 (absent) 2 h after triptan administration, in at least two attacks out of the three. Genotyping was performed by PCR and PCR-RFLP on genomic DNA extracted from peripheral blood. The impact of clinical and biological variables on consistency status of headache response to triptans was evaluated by using a binary logistic regression model with stepwise selection. Forty-three (33%) of the 130 migraine patients included in the study did not consistently respond to triptan administration. In a binary logistic regression model, STin 2.12/12 genotype (OR = 3.363, 95% CI: 1.262–8.966, P = 0.005) and non-use of migraine prophylactic medications (OR = 2.848, 95% CI: 1.019–7.959, P = 0.010) were found as significant factors increasing the odds of achieving inconsistent response to triptans. The analysis of classificatory power of the model showed moderate values of sensitivity (0.56), high specificity (0.87), and an overall prediction correctness (0.77). These results support the role of STin2 VNTR polymorphism of serotonin transporter gene as a relevant genetic factor conferring a higher risk of inconsistent response to triptans in migraine patients.

The pathophysiology of chronic neurodegenerative diseases, as Alzheimer's diseases, has remained inaccessible till recently. But this situation is changing quickly. In the past decades, genes causing familiar forms of the disease have been identified and provided the genetic framework for the emerging amyloid hypothesis. On the basis of these findings, engineered mouse models have been developed and have allowed the understanding of crucial information about the pathogenic process. Certain observations obtained by transgenic mice, however, do not easily fit with the simplest version of the amyloid hypothesis. Even if there are transgenic lines that offer robust and relatively faithful reproductions of a subset of Alzheimer's disease's features, a mouse model that recapitulates all aspects of the disease has not yet been produced. Several still not completely known factors combine to produce highly variability across transgenic mouse models. Discrepancies in neuropathology and behaviour between transgenic mouse models and human Alzheimer's disease, and among different transgenic-lines, suggest caution in the interpretation of the results. Here we try to analyze critically some of the information provided by transgenic mice but ascertaining which elements of the neuropathological and behavioural phenotype of these various strains of transgenic mice are relevant to that observed in Alzheimer's disease continues to be a challenge.

Triptans mediate vasoconstriction of meningeal vessels via stimulation of vascular 5-hydroxytryptamine (5-HT)(1B) receptors. These drugs are recommended for acute treatment in patients with moderate-to-severe migraine attacks and in those patients with mild-to-moderate headache that are not controlled adequately by other agents. Yet, approximately 25% of all migraine users and 40% of all attacks do not respond to triptan treatment. Among the hypothesis to explain this is the possibility that genetic single nucleotide polymorphisms that alter the receptor, for example changing the transcriptional rate and therefore the amount of target protein might change the clinical response to these drugs. In the present contribution, we therefore decided to evaluate whether single nucleotide polymorphisms on the 5-HT(1B) gene might contribute to inter-individual variability in clinical responses to triptans. Two polymorphisms in the promoter region of the 5-HT(1B) receptor (T-261G and A-161T) and the synonymous variation G861C in the coding region were genotyped by restriction fragment length polymorphism in 105 migraine patients. In our sample population, 71% of patients responded to triptans. Allelic and diplotype frequencies were not significantly different between responders and non-responders. On the other hand, extrapolation of in vitro data on promoter activity would suggest that patients with higher copy number of receptors respond slightly better. Our data therefore do not support the involvement of 5-HT(1B) single nucleotide polymorphisms in mediating the inter-individual variability to triptans.

We evaluated the effects of nicergoline on antioxidant defense enzymes (detoxifying enzymes), during chronic treatment with haloperidol in rats. Chronic use of haloperidol (10 weeks, 1.5 mg/kg/day) induces a significant decrease in glutathione reductase, glutathione peroxidase and superoxide dismutase activity, in selected areas of the brain. Co-administration of nicergoline (20 days, 10 mg/kg/day) significantly restored the activity of these enzymes to levels comparable to those observed in control rats. These observations suggest beneficial effects of nicergoline in the prevention and in the treatment of haloperidol-induced side effects.

Dopamine receptor agonists are protective in different models of neurodegeneration by both receptor-dependent and -independent mechanisms. We used SH-SY5Y cells, differentiated into neuron-like type, to evaluate if cabergoline, a dopamine D2 receptor agonist endowed with anti-oxidant activity, protects the cells against ischemia (oxygen–glucose deprivation model). Cabergoline protected the cells from ischemia-induced cell death in a concentration-dependent manner (EC 50 =1.2 μM), as demonstrated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, lactate dehydrogenase (LDH) release, and fluorescein diacetate–propidium iodide staining. This effect, observed even when the drug was added after oxygen–glucose deprivation, was not mediated by either dopamine D2 receptor activation or anti-apoptotic Bcl-2 protein over-expression (Western blotting analysis), but was linked to a reduction in cellular free radical loading (2′,7′-dichlorodihydrofluorescein diacetate (DCFH-DA) staining) and membrane lipid peroxidation (thiobarbituric acid-reacting test). In conclusion, cabergoline protects in vitro neurons against ischemia-induced cell death, suggesting its possible use in the therapy of other neurodegenerative diseases in addition to Parkinson's disease.

To study if cabergoline, a long-lasting specific dopamine D2 receptor agonist, has neuroprotective effects against oxidative stress, we exposed (3 h) SH-SY5Y human neuroblastoma cells to tert-butylhydroperoxide (t-BOOH; 500 microM). t-BOOH caused a 42+/-4% neuronal death, which was prevented by cabergoline (2 h before) in a concentration-dependent manner (EC(50): 1.24 microM). This effect was not antagonised by haloperidol (concentration up to 10 microM), and was associated with an increased availability of intracellular GSH contents (+30+/-11%) and a decrease in the membrane lipid peroxidation (-23+/-9%). Our data suggest that cabergoline has neuroprotective effects useful for Parkinson's disease therapy.

We evaluated the effects of 10-alpha-methoxy-9,10-dihydrolysergol (MDL) and 1-methyl-10-alpha-methoxy-9,10-dihydrolysergol (MMDL), two nicergoline metabolites, during chronic treatment with haloperidol in rats. Haloperidol induced a significant decrease in the glutathione (GSH) content in selected areas of the brain and in the liver. Prolonged administration of MDL, MMDL or nicergoline antagonized the haloperidol-induced GSH decrease. Lipid peroxidation in the cortex and striatum was suppressed by MDL, MMDL or nicergoline administration. Our results show that MDL, MMDL and nicergoline have antioxidant activity, preventing not only GSH depletion but also lipid peroxidation. These observations suggest beneficial properties of MDL and MMDL in the treatment of neuroleptic-induced side effects.

The GH3 pituitary tumor line expresses TRH receptors that stimulate phosphoinositide hydrolysis and hormone secretion. After protein kinase C was identified in GH3 cells by direct labeling with [3H]phorbol dibutyrate (PDB), the response to phorbol ester and TRH pretreatment on subsequent TRH-stimulated inositol phosphate (IP) accumulation was found to be inhibitory. Both phorbol myristate acetate (PMA) and PDB were effective in this regard at low nM concentrations within a few minutes, whereas phorbols that do not stimulate protein kinase C were without effect. Furthermore, the mono-, bis- and tris-phosphate forms of IP were all reduced by an average of 30-40% after 5 min of PMA. TRH concentration-response studies indicated a clear change in TRH efficacy induced by PMA. Finally, preincubation with TRH itself was also capable of reducing the subsequent response to TRH. Because TRH receptor action is thought to activate protein kinase C by producing diacylglycerol, these data indicate a negative feedback system via protein kinase C operative during continuous exposure to TRH in GH3 cells.

Phorbol esters are tumor promotors that directly stimulate protein kinase C activity. We asked whether these agents affect basal or receptor initiated alterations in growth hormone (GH) and prolactin release. In 4 h incubations of anterior pituitary cells, phorbol esters enhanced basal and GH releasing factor (GRF)-induced GH release. Somatostatin reduced by 38% the 4-fold stimulation of GH release induced by phorbol ester. These tumor promoters also reversed the ability of bromocriptine, a dopamine agonist, to inhibit prolactin release, with no apparent effect on basal prolactin secretion. When these agents were applied for 24 h, an increase in the basal release of both GH and prolactin was apparent. These data lead us to suggest that an intact protein kinase C system may be necessary for the full expression of GRF-stimulated GH release and dopaminergic inhibition of prolactin release.

Sulpiride, a benzamide derivative neuroleptic, was shown to significantly increase glutamic acid decarboxylase activity in substantia nigra and corpus striatum in either acutely or chronically injected male rats. Hypophysectomy completely prevented this effect suggesting an involvement of an anterior pituitary factor in the central action of sulpiride. Prolactin might possibly mediate the effects of sulpiride since it is known to increase prolactin secretion by an action at the level of the anterior pituitary. Consistent with this hypothesis was the finding of a similar increase in nigral and striatal glutamic acid decarboxylase activity in hyperprolactinemic animals in which an anterior pituitary had been implanted under the kidney capsule.

We investigated the role of arachidonic acid and certain of its metabolic products in the control of thyrotropin (TSH) secretion in vitro. Phospholipase A2 and 4 beta-phorbol 12 beta-myristate 13 alpha-acetate (PMA), which increase the intracellular availability of arachidonic acid, potently stimulated TSH release from anterior pituitary cells continuously perifused in columns and from hemipituitary glands in vitro. The effect was dose-dependent and reversible. Conversely, quinacrine (50 microM), an inhibitor of phospholipase A2 activity, inhibited basal and stimulated TSH release from pituitary cells perifused in columns. Exogenous arachidonic acid (1-100 microM) did not produce any significant effect on TSH release from hemipituitary glands in vitro. Nordihydroguaiaretic acid (NDGA), a specific inhibitor of the lipoxygenase pathway, dose-dependently inhibited basal TSH release from anterior pituitary glands incubated in vitro. Moreover, 50 microM NDGA antagonized the stimulatory effect of thyrotropin releasing hormone (TRH), phospholipase A2 and PMA on TSH release. BW755c, another lipoxygenase inhibitor, also inhibited TRH-stimulated TSH secretion. In contrast, 10-100 microM indomethacin, a potent blocker of the cyclooxygenase pathway, did not significantly modify either basal or TRH-stimulated TSH secretion from hemipituitary glands in vitro. These data suggest that arachidonic acid metabolism is involved in TSH secretion in vitro, although incubation of pituitary glands with the fatty acid did not apparently modify in our conditions basal TSH secretion. The eventual effect of arachidonate appears to be at least partially due to the action of its lipoxygenase pathway products.