Different physiological and behavioural effects of e-cigarette vapour and cigarette smoke in mice.

Nicotine is the primary addictive substance in tobacco smoke and electronic cigarette (e-cig) vapour. Methodological limitations have made it difficult to compare the role of the nicotine and non-nicotine constituents of tobacco smoke. The aim of this study was to compare the effects of traditional cigarette smoke and e-cig vapour containing the same amount of nicotine in male BALB/c mice exposed to the smoke of 21 cigarettes or e-cig vapour containing 16.8 mg of nicotine delivered by means of a mechanical ventilator for three 30-min sessions/day for seven weeks. One hour after the last session, half of the animals were sacrificed for neurochemical analysis, and the others underwent mecamylamine-precipitated or spontaneous withdrawal for the purposes of behavioural analysis. Chronic intermittent non-contingent, second-hand exposure to cigarette smoke or e-cig vapour led to similar brain cotinine and nicotine levels, similar urine cotinine levels and the similar up-regulation of α4ß2 nicotinic acetylcholine receptors in different brain areas, but had different effects on body weight, food intake, and the signs of mecamylamine-precipitated and spontaneous withdrawal episodic memory and emotional responses. The findings of this study demonstrate for the first time that e-cig vapour induces addiction-related neurochemical, physiological and behavioural alterations. The fact that inhaled cigarette smoke and e-cig vapour have partially different dependence-related effects indicates that compounds other than nicotine contribute to tobacco dependence.

Randomized trial of safinamide add-on to levodopa in Parkinson's disease with motor fluctuations.

Levodopa is effective for the motor symptoms of Parkinson's disease (PD), but is associated with motor fluctuations and dyskinesia. Many patients require add-on therapy to improve motor fluctuations without exacerbating dyskinesia. The objective of this Phase III, multicenter, double-blind, placebo-controlled, parallel-group study was to evaluate the efficacy and safety of safinamide, an α-aminoamide with dopaminergic and nondopaminergic mechanisms, as add-on to l-dopa in the treatment of patients with PD and motor fluctuations. Patients were randomized to oral safinamide 100 mg/day (n = 224), 50 mg/day (n = 223), or placebo (n = 222) for 24 weeks. The primary endpoint was total on time with no or nontroublesome dyskinesia (assessed using the Hauser patient diaries). Secondary endpoints included off time, Unified Parkinson's Disease Rating Scale (UPDRS) Part III (motor) scores, and Clinical Global Impression-Change (CGI-C). At week 24, mean ± SD increases in total on time with no or nontroublesome dyskinesia were 1.36 ± 2.625 hours for safinamide 100 mg/day, 1.37 ± 2.745 hours for safinamide 50 mg/day, and 0.97 ± 2.375 hours for placebo. Least squares means differences in both safinamide groups were significantly higher versus placebo. Improvements in off time, UPDRS Part III, and CGI-C were significantly greater in both safinamide groups versus placebo. There were no significant between-group differences for incidences of treatment-emergent adverse events (TEAEs) or TEAEs leading to discontinuation. The addition of safinamide 50 mg/day or 100 mg/day to l-dopa in patients with PD and motor fluctuations significantly increased total on time with no or nontroublesome dyskinesia, decreased off time, and improved parkinsonism, indicating that safinamide improves motor symptoms and parkinsonism without worsening dyskinesia.

Long-term efficacy and safety of safinamide as add-on therapy in early Parkinson's disease.

BACKGROUND AND PURPOSE: Safinamide is an α-aminoamide with both dopaminergic and non-dopaminergic mechanisms of action in Phase III clinical development as a once-daily add-on to dopamine agonist (DA) therapy for early Parkinson's disease (PD). METHODS: Study 017 was a 12-month, randomized, double-blind, placebo-controlled pre-planned extension study to the previously reported Study 015. Patients received safinamide 100 or 200 mg/day or placebo added to a single DA in early PD. The primary efficacy endpoint was the time from baseline (Study 015 randomization) to 'intervention', defined as increase in DA dose; addition of another DA, levodopa or other PD treatment; or discontinuation due to lack of efficacy. Safinamide groups were pooled for the primary efficacy endpoint analysis; post hoc analyses were performed on each separate dose group. RESULTS: Of the 269 patients randomized in Study 015, 227 (84%) enrolled in Study 017 and 187/227 (82%) patients completed the extension study. Median time to intervention was 559 and 466 days in the pooled safinamide and placebo groups, respectively (log-rank test; P = 0.3342). In post hoc analyses, patients receiving safinamide 100 mg/day experienced a significantly lower rate of intervention compared with placebo (25% vs. 51%, respectively) and a delay in median time to intervention of 9 days (P < 0.05; 240- to 540-day analysis). CONCLUSIONS: The pooled data from the safinamide groups failed to reach statistical significance for the primary endpoint of median time from baseline to additional drug intervention. Post hoc analyses indicate that safinamide 100 mg/day may be effective as add-on treatment to DA in PD.

Comparison of the potency of 10 different brands of Serenoa repens extracts.

BACKGROUND: The extract of Serenoa repens is the phytopharmaceutical product most often used for the treatment of urological symptoms associated with benign prostatic hyperplasia (BPH). Several extracts are commercially available but extraction processes vary between manufacturers and thus not all these products are equivalent in terms of active ingredient content and composition of preparations. AIM: As there is a paucity of comparative studies, we compared the activity of different extracts of Serenoa repens widely available on the world market. MATERIALS AND METHODS: Beltrax Uno, Permicaps, Permixon, Prostadyn, Prostagutt, Prostamen, Prostamol Uno, ProstaX, Urocaps and Urogutt were assayed for 5-alpha-reductase activity on 10 day fibroblasts and epithelial cells cocultures. Human fibroblast growth factor (hFGF)-induced-proliferation inhibition was also assayed. RESULTS: As to extract activity, differences were observed between the tested extracts, but all were able to inhibit 5-a-reductase types I and II isoenzymes (5alphaR-I and 5alphaR-II) as well as fibroblast proliferation. CONCLUSIONS: Extract potency differs between products and so does proliferation inhibition potency. Quantitative and qualitative variations in the active ingredient are likely to account for these differences.

Feedback dose alteration significantly affects probability of pathogen eradication in nosocomial pneumonia.

Nosocomial pneumonia (NP) is associated with considerable morbidity and mortality. Data have shown that inadequate initial antibiotic therapy is a major risk for infection-attributed mortality. The aim of the present study was to measure antibiotic concentration and minimum inhibitory concentration (MIC) in infected hospitalised patients early in therapy, in order to determine whether dose alterations, in those with low drug concentrations, could affect outcomes. Only patients treated with aminoglycosides, fluoroquinolones, and beta-lactams were evaluated. MICs were determined using standard National Committee for Clinical Laboratory Standards procedures. Antibiotics were assayed using validated high-performance liquid chromatographic methods. Pharmacokinetic/pharmacodynamic markers adopted were: aminoglycoside peak/MIC ratio >or=8 mg L(-1); fluoroquinolone peak/MIC >or=10 mg L(-1); beta-lactam peak/MIC >or=4 mg L(-1) and time that plasma levels remain above the MIC >or=70%. 638 patients with NP were included in the study. In 205 patients, both drug concentration and isolate MIC were available, while in other patients, used as controls, one or both parameters were lacking. For clinical outcome, the Acute Physiology and Chronic Health Evaluation II score (p<0.0001), the presence of combination therapy (p = 0.0014) and whether both MIC and drug concentration(s) were measured (p = 0.0002) significantly affected the probability of a good outcome. For microbiological outcome, the MIC for the beta-lactams (

Long-term inhibition of glioma growth by systemic administration of human PEX.

AIM: The growth of gliomas depends on the balance of factors stimulating or inhibiting angiogenesis, tumor cell invasion and proliferation. The administration of endogenous inhibitors to experimental human gliomas in animal models resulted in a significant inhibition of tumor growth. It is becoming apparent that resistance can develop over time to many types of endogenous inhibitors and seems to be influenced by the tumor type and system of delivery. METHODS: We recently isolated a potent endogenous inhibitor, called human PEX, from human glioma cells in culture. Human PEX is a potent inhibitor of angiogenesis, tumor and endothelial cell proliferation and migration. In this paper, we investigated the ability of human PEX to sustain inhibition of glioma growth for a prolonged period of time. We initially developed a recombinant form of the inhibitor and showed that this form had similar in vitro and in vivo activities to the natural one. Human PEX was then administered to nude mice intracranial human glioma model, in combination with metronomic chemotherapy, for a period of 185 days, starting 15 days after tumor cells implantation. RESULTS: Our data showed that the systemic administration of human PEX mantained a very prolonged inhibition of glioma growth (50% survival of animals treated with 2 mg/kg/days was 160 days vs 24 days of the control) and had a synergistic effect with low dose chemotherapy. Histological analysis of tumors, showed that treatment with PEX was associated with a decrease of vascularity, cell proliferation, and increase in apoptosis. CONCLUSION: These data indicate that human PEX controls tumor growth by separate mechanisms. In addition, treatment with PEX produced well delineated tumors, indicating the persistence of a direct anti-invasive effect of the molecule even after a prolonged period of treatment.

Simultaneous inhibition of glioma angiogenesis, cell proliferation, and invasion by a naturally occurring fragment of human metalloproteinase-2.

Angiogenesis, tumor cell proliferation, and migration are the hallmarks of solid tumors, such as gliomas. This study demonstrates that a fragment derived from the autocatalytic digestion of matrix metalloproteinase (MMP)-2, called PEX, acts simultaneously as an inhibitor of glioma angiogenesis, cell proliferation, and migration. PEX is detected in the cultured medium of various human glioma, endothelial, breast, and prostate carcinoma cell lines. PEX is purified from the medium of glioma cell lines by chromatography, where PEX is constitutively expressed as a free and a TIMP-2-bound form. In human glioma tissue, PEX expression correlates with histological subtype and grade and with alpha v beta 3 integrin expression to which it is bound. Systemic administration of PEX to s.c. and intracranial human glioma xenografts results in a 99% suppression of tumor growth with no signs of toxicity. Thus, PEX is a very promising candidate for the treatment of human malignant gliomas.

Low-dose chemotherapy combined with an antiangiogenic drug reduces human glioma growth in vivo.

This study evaluates the efficacy of the combination of an antiangiogenic drug and conventional chemotherapeutics for the treatment of experimental human gliomas. As an antiangiogenic, we used recombinant human PEX, a fragment of matrix metalloproteinase-2 that we have previously shown to have a significant antimitotic, anti-invasive, and antiangiogenic properties against human glioblastoma in vitro and in vivo. We used carboplatin and etoposide as the two chemotherapeutic drugs routinely used in our institution (Ospedale Maggiore de Milano) for the treatment of malignant gliomas. Conventional chemotherapeutic drugs were administered at high dose or at a low and semicontinuous regimen. Combined treatment of high-dose chemotherapy and PEX did not produce an improvement of survival in comparison with chemotherapy alone, but it was associated with a decrease in tumor volume, vascularity, and proliferative index and an increased apoptosis. All of these animals experienced severe side effects. The longest survival was documented in animals submitted to low and semicontinuous chemotherapy and antiangiogenic treatment. This regimen was associated with no side effects, marked decrease in tumor volume, vascularity, and proliferative index, and an increased apoptosis. Our data suggest that low-dose chemotherapy in combination with PEX can be successfully used against human malignant glioma in vivo.

2-N-acylaminoalkylindoles: design and quantitative structure-activity relationship studies leading to MT2-selective melatonin antagonists.

Several indole analogues of melatonin (MLT) were obtained by moving the MLT side chain from C(3) to C(2) of the indole ring. Binding and in vitro functional assays were performed on cloned human MT1 and MT2 receptors, stably transfected in NIH3T3 cells. Quantitative structure-activity relationship studies showed that 4-methoxy-2-(N-acylaminomethyl)indoles, with a benzyl group in position 1, were selective MT2 antagonists and, in particular, N-[(1-p-chlorobenzyl-4-methoxy-1H-indol-2-yl)methyl]propanamide (12) behaved as a pure antagonist at MT1 and MT2 receptors, with a 148-fold selectivity for MT2. We present a topographical model that suggests a lipophilic group, located out of the plane of the indole ring of MLT, as the key feature of the MT2 selective antagonists.

Synthesis, pharmacological characterization and QSAR studies on 2-substituted indole melatonin receptor ligands.

A number of 6-methoxy-1-(2-propionylaminoethyl)indoles, carrying properly selected substituents at the C-2 indole position, were prepared and tested as melatonin receptor ligands. Affinities and intrinsic activities for the human cloned mt1 and MT2 receptors were examined and compared with those of some 2-substituted melatonin derivatives recently described by us. A quantitative structure activity relationship (QSAR) study of the sixteen 2-substituted indole compounds, 5a-k, 1, 8-11, using partial least squares (PLS) and multiple regression analysis (MRA) revealed the existence of an optimal range of lipophilicity for the C2 indole substituent. There are also indications that planar, electron-withdrawing substituents contribute to the affinity by establishing additional interactions with the binding pocket. No mt1/MT2 subtype selectivity was observed, with the relevant exception of the 2-phenethyl derivative 5e, which exhibited the highest selectivity for the h-MT2 receptor among all the compounds tested (MT2/mt1 ratio of ca. 50). Conformational analysis and superposition of 5e to other reported selective MT2 ligands revealed structural and conformational similarities that might account for the MT2/mt1 selectivity of 5e.

A new melatonin receptor ligand with mt1-agonist and MT2-antagonist properties.

It has been difficult, so far, to obtain melatonin analogs possessing high selectivity for the respective melatonin receptors, mt1 and MT2. In the present work, we report the synthesis and pharmacological characterization of a new compound N-¿2-[5-(2-hydroxyethoxy)-1H-indol-3-yl)] ethyl¿ acetamide or 5-hydroxyethoxy-N-acetyltryptamine (5-HEAT). To assess the activity of the compound, the following tests were performed: affinity determination for the high- and low-affinity receptor states (2-[125I]iodomelatonin binding), potency and intrinsic activity in inducing G protein activation ([35S]GTPgammaS binding assay). 5-HEAT showed little selectivity for the mt1 receptor, with pKi values of 7.77 for mt1 and 7.12 for the MT2 receptors, respectively. 5-HEAT was able to differentiate between the high- and the low-affinity receptor states in the mt1 but not in the MT2 receptor. 5-HEAT induced a high level of G protein activation when acting through the mt1 receptor, with a relative intrinsic activity of 0.92. On the contrary, it elicited only minimal MT2 receptor-mediated G protein activation, with a relative intrinsic activity of 0.16, and was also able to inhibit the melatonin-induced MT2 receptor-mediated G protein activation, with a pKB value of 7.4. In conclusion, it appears that 5-HEAT possesses very different efficacies at the two melatonin receptors, behaving as a full melatonin receptor agonist at the mt1 and as an antagonist/weak partial agonist at the MT2 receptor. Therefore, it is a promising ligand for use in functional studies aimed at distinguishing between the effects mediated by the different melatonin receptors in the human.

Ligand efficacy and potency at recombinant human MT2 melatonin receptors: evidence for agonist activity of some mt1-antagonists.

NIH3T3 fibroblast cells transfected with the full-length coding region of the MT2 human melatonin receptor stably expressed the receptor that is coupled to a pertussis toxin-sensitive G protein and exhibits high affinity for melatonin (K(I) = 261 pM). The order of apparent affinity for selected compounds was: 4-phenyl-2-propionamidotetralin (4P-PDOT) > 2-phenylmelatonin > 2-iodomelatonin > 2-bromomelatonin > 6-chloromelatonin > or = melatonin > luzindole > N-acetyl-tryptamine > or = N-[(2-phenyl-1H-indol-3-yl)ethyl]cyclobutanecarboxamide (compound 6) > N-acetylserotonin. 4P-PDOT exhibited a very high selectivity (approximately 22,000 times) for the MT2 receptor with respect to the mt1 receptor subtype, as tested in comparative experiments with membrane preparations from NIH3T3 cells stably transfected with the human mt1 receptor. MT2 melatonin receptors mediated incorporation of [35S]-GTPgammaS into isolated membranes via receptor catalyzed exchange of [35S]-GTPgammaS for GDP. The relative intrinsic activity and potency of the compounds were subsequently studied by using [35S]-GTPgammaS incorporation. The order of potency was equal to the order of apparent affinity. Melatonin and full agonists increased [35S]-GTPgammaS binding by 250% over basal (taken as 100%). Luzindole did not increase basal [35S]-GTPgammaS binding but competitively inhibited melatonin-stimulated [35S]-GTPgammaS binding, thus exhibiting antagonist action. The other two mt1 antagonists used here, 4P-PDOT and N-[(2-phenyl-1H-indol-3-yl)ethyl]cyclobutanecarboxamide, behaved as partial agonists at the MT2 subtype, with relative intrinsic activities of 0.37 and 0.39, respectively. These findings show, for the first time, important differences in the intrinsic activity of analogues between the human mt1 and MT2 melatonin receptor subtypes.

2-[N-Acylamino(C1-C3)alkyl]indoles as MT1 melatonin receptor partial agonists, antagonists, and putative inverse agonists.

The synthesis of several novel indole melatonin analogues substituted at the 2-position with acylaminomethyl (8-11), acylaminoethyl (5a-k), or acylaminopropyl (13) side chains is reported. On the basis of a novel in vitro functional assay (specific binding of [35S]GTPgammaS), which can discriminate agonist from partial agonist, antagonist, and inverse agonist ligands, 5a,g, h,j and 13 were shown to be partial agonists, 5d,e and 8-11 competitive antagonists, and 5b,c,k putative inverse agonists. Binding and functional assays were performed on cloned human MT1 receptor. Structure-activity relationship considerations indicate that N-[1-aryl-2-(4-methoxy-1H-indol-2-yl)(C1-C2)alkyl]alkanamides represent a lead structure for this type of ligands.

Neuroendocrine, immunohistochemical, and ultrastructural study of pineal region tumors.

Thirteen patients with tumors in the pineal region were submitted to pre- and post-operative blood sampling (08:00, 14:00, 20:00, and 02:00 hr) for three or four consecutive days. A single cerebrospinal fluid (CSF) sample was collected at surgery, and melatonin levels determined. In all patients, serum and CSF beta subunit of human chorionic gonadotrophin (betaHCG), carcino embryonic antigen (CEA), and alpha-fetoprotein (AFP) levels were measured. Histology revealed four pineocytomas, one pineoblastoma, four germinomas, one immature teratoma, one pilocytic astrocytoma, one lymphoma, and one meningioma. Serum and CSF levels of serological biomarkers were normal, except for one of the germinoma cases. In most patients, alteration either in the circadian rhythm or in the melatonin concentration was observed before surgery. In benign neoplasms the circadian rhythm was conserved. In pineoblastoma, lymphoma, and three out of four germinomas, melatonin concentrations were undetectable. In one case of germinoma, melatonin levels were high, with the circadian rhythm being abolished. According to conventional histology, all germinomas were similar. Therefore, in a rare case of pineal germinoma with high melatonin levels, the tissue was subjected to an in depth investigation (immunohistochemical and ultrastructural) in order to determine the pathology and the possible differences from the other typical germinomas. Results were compared to those provided from other pineal neoplasms. Electron microscopy examination detected the presence of clusters of intermediate filaments and numerous electrondense granules only in the case of a germinoma producing melatonin.

Melatonin receptor ligands: synthesis of new melatonin derivatives and comprehensive comparative molecular field analysis (CoMFA) study.

The CoMFA methodology was applied to melatonin receptor ligands in order to establish quantitative structure-affinity relationships. One hundred thirty-three compounds were considered: they were either collected from literature or newly synthesized in order to gain information about the less explored positions. To this end, various melatonin derivatives were prepared and their affinity for quail optic tecta melatonin receptor was tested. Compounds were aligned on the putative active conformation of melatonin proposed by our previously reported pharmacophore search, and their relative affinities were calculated from the displacement of 2-[125I]-iodomelatonin on different tissues expressing aMT receptors. Compounds were grouped into three sets according to their topology. Subset A: melatonin-like compounds; subset B: N-acyl-2-amino-8-methoxytetralins and related compounds; subset C:N-acyl-phenylalkylamines and related compounds. CoMFA models were derived for each set, using the steric, electrostatic, and lipophilic fields as structural descriptors; the PLS analyses were characterized by good statistical parameters, taking into account the heterogeneity of the binding data, obtained with different experimental protocols. From the CoMFA model for the melatonin-like compounds, besides the well-known positive effect of 2-substitution, a low steric tolerance for substituents in 1, 6, and 7, and a negative effect of electron-rich 4-substituents were observed; the information provided by the newly synthesized compounds was essential for these results. Moreover, a comprehensive model for the 133 compounds, accounting for a common alignment and a common mode of interaction at the melatonin receptor, was derived (Q2 = 0.769, R2 = 0.905). This model validates our previously reported pharmacophore search and offers a clear depiction of the structure-affinity relationships for the melatonin receptor ligands.

Pharmacological characterization of the human melatonin Mel1a receptor following stable transfection into NIH3T3 cells.

1. Mouse fibroblasts (NIH3T3) transfected with the full-length coding region of the Mel1a melatonin receptor stably expressed the receptor, coupled to a pertussis toxin-sensitive G-protein(s) and exhibiting high affinity and adequate pharmacological profile. 2. The receptor protein had the tendency of a strong coupling to the G-protein and therefore low-affinity state was induced by uncoupling the receptor from its G-protein in presence of high concentrations of NaCl (500-700 mM) and/or GTPgammaS (100 microM). Thereafter, the affinity of a series of melatonin analogues was determined to both, high- and low-affinity receptor states, thus providing a basis for the prediction of their efficacy, according to the ternary complex model. 3. The cells were subsequently used to study the agonist-induced G-protein activation, determined by calculating the rate of GDP-GTP exchange measured in presence of 35S-labelled GTPgammaS. The natural ligand melatonin induced a significant increase in the GDP-GTP exchange rate, the presence of GDP and NaCl being necessary to observe this effect. 4. The full agonists 2-phenylmelatonin, 2-bromomelatonin and 6-chloromelatonin equally induced an increase of the GDP-GTP exchange. 5-Hydroxy-N-acetyltryptamine activated the GTP-GDP exchange to a much lesser extent (53%) than melatonin, thus behaving as a partial agonist. As predicted by the model, the melatonin antagonist (N-[(2-phenyl-1H-indol-3-yl)ethyl]cyclobutanecarboxamide) was without effect on basal G protein activation. Coincubation of this compound with melatonin induced a dose-dependent rightward shift in the melatonin concentration-effect curve, thus exhibiting the behaviour of a competitive and surmountable antagonist. 5. Using the equation proposed by Venter (1997) we were able to determine that there were no 'spare' receptors in the system. Therefore, the approach proposed in the present work can be successfully used for the determination of 'drug action' at the level of the human Mel1a melatonin receptor and evaluation of the efficacy of new selective melatonin analogues.

Abnormal 24-hour urinary excretory pattern of 6-sulphatoxymelatonin in both phases of cluster headache.

The typical cyclic occurrence of cluster headache suggests the involvement of hypothalamic rhythm regulating centers in the pathogenesis of this primary headache. In previous studies, reduced 24-h plasma melatonin levels during the cluster period, loss of circadian melatonin secretion in remission, as well as permanently reduced excretion of urinary melatonin in both illness phases have been reported, supporting the hypothesis of a hypothalamic derangement. In this study, the 24-h urinary excretion of the main melatonin metabolite, 6-sulphatoxymelatonin, was evaluated in 20 cluster period cluster headache patients. Thirteen were retested 12 months later, in the same period of the year, during remission. Fourteen age- and sex-matched healthy subjects were the controls. As expected, significantly higher levels of 6-sulphatoxymelatonin were present in nocturnal urine than in day-time urine in controls, while in both cluster headache groups urinary levels of this metabolite did not differ between day and night. Nocturnal levels of 6-sulphatoxymelatonin were significantly lower in both cluster headache groups than controls. Day-time levels did not differ significantly between the groups. Altered excretion of urinary 6-sulphatoxymelatonin even during remission indicates that at least some of these anomalies are independent of the pain, and provides further evidence of involvement of the hypothalamic rhythm regulating centers in cluster headache.

Conformationally restrained melatonin analogues: synthesis, binding affinity for the melatonin receptor, evaluation of the biological activity, and molecular modeling study.

The design, synthesis, and biological profile of several indole melatonin analogues with a conformationally restricted C3 amidoethane side chain are presented. Examination of the accessible conformations of the melatonin side chain led us to explore some of its fully or partially restricted analogues, 2-12, the binding affinity values of which were utilized to gain further insight on the melatonin binding site. Two pharmacophoric models have been devised for melatonin and the active compounds by conformational analysis and superimposition performed using the DISCO program. In these models, the melatonin side chain can adopt a gauche/anti conformation out of the indole plane. Another contribution of this study regards the observation of a possible binding point interaction around the C2 position of the indole, as suggested by the remarkably increased binding affinity observed in the C2-substituted analogues 6 and 9 and especially in the more rigid analogue 5. The biological activity and the efficacy of the new compounds were tested by measuring the inhibition of the forskolin-stimulated cAMP accumulation and the GTP gamma S index. Both analyses demonstrated that all of the compounds were full agonists with the exception of 4 and 9, which showed a slight reduction in efficacy and would seem to be partial agonists.

1-(2-Alkanamidoethyl)-6-methoxyindole derivatives: a new class of potent indole melatonin analogues.

A new series of indole melatonin analogues, bearing the amido ethyl side chain attached at the N-1 position of the indole nucleus, were synthesized and tested for their affinity for the melatonin receptor isolated from quail optic tecta in a series of in vitro ligand-binding experiments using 2-[125I]iodomelatonin as the labeled ligand. The biological activity was evaluated using two models: effects on the forskolin-stimulated cAMP accumulation in explants from quail optic tecta and evaluation of the GTP gamma S index derived from competition experiments performed in the absence or presence of GTP gamma S. Compounds 2a and 2k-n, obtained by shifting the methoxy group and the ethylamido side chain from the C-5 and C-3 positions of melatonin to the C-6 and N-1 positions of the indole nucleus, exhibited an affinity similar to that of melatonin itself, as well as full agonist activity. Optimization of the C-2 substituent by introducing Br, phenyl, or COOCH3 (2b-d) resulted in a significantly enhanced affinity (in the picomolar range) and improved agonist biological activity. Compounds lacking the methoxy group and bearing an N-alicyclic group (2h-j) behaved as partial agonists or antagonists.

Plasma tryptophan levels and tryptophan/neutral amino acid ratios in obsessive-compulsive patients with and without depression.

We have studied fasting plasma tryptophan (TRP) levels and tryptophan/large neutral amino acid (TRP/LNAA) ratios in 12 patients with obsessive-compulsive disorder (OCD) and 12 patients with OCD and a coexisting current diagnosis of major depressive disorder (OCD-MDD). Assessments were made at baseline and after 6 weeks of treatment with fluvoxamine. OCD-MDD patients had significantly lower baseline TRP levels and TRP/LNAA ratios than OCD patients. After 6 weeks of fluvoxamine treatment, OCD-MDD patients had significant increases in plasma TRP and TRP/LNAA ratio, whereas OCD patients had non-significant decreases. Our data suggest that a major depressive syndrome could be a state variable affecting the changes in plasma TRP and TRP/LNAA ratio in OCD patients.