Search

Background: Recently, patents of several atypical antipsychotics have reached their expiration date. Aims: The purpose of the study was to highlight whether modifications of economic/scientific factors may be associated with possible changes in ongoing clinical research on antipsychotic drugs. Methods: A large systematic analysis was used to depict the time-dependent distribution of published research articles addressing the clinical properties of oral risperidone and olanzapine conventional tablets, two largely prescribed atypical antipsychotics for which the patents have already expired in most of the countries. Results: The systematic analysis indicated that the time-dependent distribution of the selected research articles followed a wave-shape pattern. A dramatic decline of primary and secondary analyses investigating the clinical effects of oral risperidone and olanzapine has occurred in the last decade, complemented by an expected strong reduction in the numbers of industrial-supported clinical studies and a smaller, but significant, decline in the amount of independent research articles. Conclusions: To date, greater involvement of independent research seems to be the only realistic chance to properly continue the investigation on the clinical properties of oral risperidone and olanzapine conventional tablets, as well as those of other off-patent antipsychotic drugs. However, the limits and potentialities of independent research in accomplishing such a demanding and enduring scientific effort should be addressed.

Ethnopharmacological relevance The burden of disease caused by mental and neurological disorders is increasing globally, to a disproportionate degree in Latin America. In contrast to the many psychoactive plants with a use history in Mesoamerican cultures, the translation to the wider population of knowledge around numerous botanicals used contemporarily by indigenous Mesoamerican societies to treat psychological and neurological disorders did not receive the same attention. Material and methods We used the previously published Mesoamerican Medicinal Plant Database to extract species and associated botanical drugs used as treatments for illnesses associated with the nervous system by Mesoamerican cultures in Belize, Guatemala, and Mexico. With the critical use of published pharmacological literature, the cross-culturally most salient genera are systematically reviewed. Results From 2188 plant taxa contained in the database 1324 are used as treatments for illnesses associated with the nervous system. The ethnomedical data was critically confronted with the available biomedical literature for the 58 cross-culturally most salient genera. For a considerable proportion of the frequently used taxa, preclinical data are available, mostly validating ethnomedicinal uses. Conclusion This quantitative approach facilitates the prioritization of taxa for future pre-clinical, clinical and treatment outcome studies and gives patients, practitioners, and legislators a fundamental framework of evidence, on which to base decisions regarding phytomedicines.

HBD: c.442T>C is a new mutation at the stop codon (TGA>CGA) of the δ-globin gene, which produces a new codon for arginine. This substitution causes a 51 nucleotides longer open reading frame determining the synthesis of a potential larger δ subunit, which is a probable target of mechanisms for the degradation of aberrant proteins as well as the defective synthesized mRNA molecules, and may also be rapidly degraded by a variety of RNA surveillance pathways. We identified this molecular defect in four patients: three women with a reduced HbA2 level and a 37-year-old male showing the typical phenotype of an α-thalassemia (α-thal) carrier with reduced values of red cell indices and normal HbA2 level (2.5%). The mutation on the δ-globin gene was found to have been coinherited with a β-globin gene defect leading to a normalized HbA2 level. These data support the necessity of investigating these cases at a molecular level, particularly if the partner is also a β-thalassemia (β-thal) carrier. The present data emphasizes the importance of a careful evaluation of correlation between genotypes resulting from DNA analysis and phenotypes, especially in cases of atypical hematological parameters, in order to carry out an adequate diagnostic process finalized to appropriate genetic counseling.

Previous studies demonstrated that Withania somnifera Dunal (WS), a safe medicinal plant, prevents the development of tolerance to the analgesic effect of morphine. In the present study, we investigated whether WS extract (WSE) (100 mg/kg, i.p.) may also modulate the analgesic effect induced by acute morphine administration (2.5, 5, 10 mg/kg, s.c.) in the tail-flick and in the hot plate tests, and if it may prevent the development of 2.5 mg/kg morphine-induced rebound hyperalgesia in the low intensity tail-flick test. Further, to characterize the receptor(s) involved in these effects, we studied, by receptor-binding assay, the affinity of WSE for opioid (mu, delta, k), cannabinoid (CB1, CB2), glutamatergic (NMDA), GABAergic (GABAA, GABAB), serotoninergic (5HT2A) and adrenergic (alpha2) receptors. The results demonstrated that (i) WSE alone failed to alter basal nociceptive threshold in both tests, (ii) WSE pre-treatment significantly protracted the antinociceptive effect induced by 5 and 10 mg/kg of morphine only in tail-flick test, (iii) WSE pre-treatment prevented morphine-induced hyperalgesia in the low intensity tail-flick test, and (iv) WSE exhibited a high affinity for the GABAA and moderate affinity for GABAB, NMDA and delta opioid receptors. WSE prolongs morphine-induced analgesia and suppresses the development of morphine-induced rebound hyperalgesia probably through involvement of GABAA, GABAB, NMDA and delta opioid receptors. This study suggests the therapeutic potential of WSE as a valuable adjuvant agent in opioid-sparing therapies.

Considering the interesting pharmacological profile of the delta (?) selective opioid agonist compound SNC-80, conformationally constrained analogs containing two diazatricyclodecane ring systems in place of dimethylpiperazine core motif were synthesized. The compounds showed subnanomolar or low nanomolar ? opioid receptor binding affinity. Depending upon the substituents on the diazatricyclodecane ring, these compounds displayed varying selectivity for ? opioid receptor over ? and ? receptors. Amongst the novel compounds, 1Aa showed the more interesting biological profile, with higher ? affinity and selectivity compared to SNC-80. The ? receptor agonist profile and antinociceptive activity of 1Aa were confirmed using ex-vivo (isolated mouse vas deferens) and in vivo (tail flick) assays. © 2013 Elsevier Masson SAS. All rights reserved.

ResumenHay diferencias clínicamente importantes en la seguridad y tolerabilidad de los antipsicóticos dependiendo de los distintos tipos y de sus formulaciones. Las características de la interacción bioquímica entre el antipsicótico y el receptor D2 pueden ser la base de estas diferencias. Este artículo revisa la información actual sobre la relación entre la ocupación del antipsicótico por el receptor y la respuesta clínica. Se hizo una búsqueda en la literatura introduciendo las palabras clave “antipsicótico o neuroléptico”, “receptor”, “ocupación”, “dopamina” y “D2” y se complementó con búsquedas manuales en la literatura. Los datos de las pruebas de neuroimagen y clínicas, generalmente, confirmaron que la ocupación óptima de los receptores D2 del núcleo estriado se sitúa en “una ventana térapeutica” entre ∼ 65% y ∼ 80%; sin embargo, las propiedades farmacocinéticas y farmacodinámicas del fármaco también deberían tenerse en cuenta para evaluar totalmente sus efectos terapéuticos. Deberían realizarse nuevas investigaciones, quizá, en modelos preclínicos, para deetrminar la ocupación de los receptores D2 en varias regiones cerebrales y la duración óptima del bloqueo de los receptores D2 para maximizar los perfiles de eficacia y tolerabilidad de los antipsicóticos atípicos y mejorar los resultados del tratamiento de los pacientes con esquizofrenia.

Withania somnifera (L.) Dunal extracts (WSEs) may possess therapeutic perspectives in the treatment of inflammation and pain. We aimed to evaluate the antinociceptive property of a WSE in the formalin test and to investigate the involvement of several neurotransmitter systems in this effect. The time spent licking the formalin-injected paw was recorded in CD1 mice after pretreatment with increasing doses of WSE. Also, c-Fos spinal cord expression and the effects of different compounds were investigated under these experimental conditions. Finally, the efficacy of WSE was analyzed following an injection of glutamate. WSE reduced the antinociceptive response during the tonic but not the acute phase of the formalin test and decreased formalin-induced c-Fos expression in spinal neurons. These effects were antagonized by the opioid antagonist naltrexone, whereas GABA, cannabinoid, δ-opioid, and nitric oxide compounds were ineffective. The administration of WSE also reduced nociception and c-Fos expression induced by glutamate injection. These results showed that WSE is effective in assays of chemical-induced nociception, indicating that this plant has potential valuable properties for the treatment of specific painful conditions. The antinocicetive effects of WSE in the formalin test appeared to be specifically mediated by the opioidergic system, although the involvement of the glutamatergic system cannot be excluded.

In the last 25. years, the Positive and Negative Syndrome Scale (PANSS) has been largely used to assess schizophrenia symptom intensity, but little information is available on how this scale was generally applied when evaluating the efficacy of schizophrenia therapies in randomized clinical trials. In the attempt to address this topic, a systematic PubMed Search was carried out using the keywords "PANSS" and "Randomized Clinical Trials". The analysis of retrieved articles highlighted that PANSS has constituted a suitable psychometric instrument to investigate the efficacy of pharmacological and non-pharmacological therapies. However, the information potentially provided by this scale was only partially reported in research articles, when characterizing the symptomatic features of patients at baseline. Furthermore, a consensus is needed to identify methodological strategies that may properly adapt PANSS-subscale structure with the symptomatic profiles of individuals enrolled in randomized controlled trials. The possibility that PANSS interview procedures and enrollment eligibility criteria may influence the symptomatic composition of patients involved in these studies is also discussed.

Similarly to acute rat catalepsy, “early onset” vacuous chewing movements (VCMs) induced by subchronic treatment with antipsychotic have recently been proposed as a model of human extrapyramidal symptoms. In the present study, the propensities of haloperidol and risperidone in inducing rat “early onset” VCMs were compared using doses of the two antipsychotics that acutely induce similar catalepsy. Comparable rat catalepsy states were observed when the effects produced by 0.1, 0.5, and 1 mg/kg of haloperidol were compared with those induced by 1, 4, and 10 mg/kg of risperidone, respectively. These doses of the two antipsychotics were then administered twice a day for 4 weeks and VCMs scored after 12 h, 5 days, or 3 weeks of drug withdrawal. Among the haloperidol-treated groups, only those rats injected with 0.5 and 1 mg/kg showed high levels of VCMs after 12 h and 5 days of drug withdrawal when compared to vehicle-treated rats, while basal levels of VCMs were reached after 3 weeks from the last injection. High VCMs levels were observed in risperidone-treated rats only at the dose of 10 mg/kg and after 12 h of drug withdrawal, but not after 5 days or 3 weeks. The present results indicated that haloperidol possessed a much higher propensity to induce rat “early onset” VCMs than risperidone.

The effect on rat catalepsy induced by Δ9-tetrahydrocannabinol (Δ9-THC) in association with haloperidol (HP) or clozapine (CLOZ) administration was investigated. Δ9-THC dose-dependently increased HP (0.05–1 mg kg−1, s.c.)-induced rat catalepsy, while no catalepsy was observed after CLOZ (1–20 mg kg−1, s.c.) or Δ9-THC+CLOZ administration. The CB1 antagonist SR141716A (0.5–5 mg kg−1, i.p.) reversed the increase mediated by Δ9-THC on HP-induced catalepsy. The D2 agonist quinpirole completely reversed the catalepsy induced by both HP and HP+Δ9-THC; however, higher doses of quinpirole were needed in the presence of Δ9-THC. The M1 antagonist scopolamine and α2 antagonist yohimbine were able to reduce the catalepsy induced by HP and HP+Δ9-THC in a similar manner. CLOZ and the 5-HT2A/2C antagonists ritanserin, RS102221 and SB242084 were more effective in antagonizing HP than HP+Δ9-THC-induced catalepsy. HP and CLOZ failed to inhibit in vitro [3H]CP-55,940 binding, while Δ9-THC and SR141716A did not show an appreciable affinity for the D2 receptor. It was suggested that the different effects on rat catalepsy induced by Δ9-THC following HP or CLOZ administration may depend on the receptor-binding profiles of the two antipsychotics. The preferential use of CLOZ rather than HP in the treatment of psychotic symptoms in cannabis abusers was discussed. British Journal of Pharmacology (2003) 140, 520–526. doi:10.1038/sj.bjp.0705478

1 The neuroleptic [(3)H]-haloperidol (HP) was taken up in synaptosomes prepared from rat brain, in a temperature-, sodium ion-, and energy-dependent process. 2 The highest concentration of uptake sites (V(max)=2.37 pmol mg(-1) protein min(-1)) was in the striatum with the other brain areas displaying lower (by 50-70%) values. 3 The affinity values (K(m) approximately equal to 40 nM) were similar in all brain areas considered. 4 The pharmacological characterization did not indicate a well-defined group of inhibitors, which suggested that HP might not use a transporter for recognized neurotransmitters. 5 The HP metabolites tested, including HPTP, were competitive inhibitors of [(3)H]-HP uptake, an indirect indication that they may actively enter the striatal nerve endings through the same carrier. 6 Since the uptake process was partially affected by the incubation of [(3)H]-HP in the presence of several antagonists of HP-transforming cytochrome P450 isoforms, the binding of HP at some enzyme sites inside the synaptosome cannot be excluded. 7 In conclusion, the present results suggest that HP may be actively transported in the rat brain.

Recently, the gastrointestinal pharmacology of cannabinoid CB(1) receptors has been extensively explored. We employed western blotting and immunohistochemistry techniques to study the distribution of the cannabinoid CB(1) receptor protein in the mouse gastroenteric tract. The cannabinoid CB(1) receptor peptide was detected by western blotting only in its glycosylated form (63 kDa) with a significant differential distribution. The highest levels of expression were detected in the stomach and in the colon, while the pyloric valve was devoid of any cannabinoid CB(1) receptor protein. The immunohistochemical study showed intense cannabinoid CB(1) receptor immunoreactivity in ganglia subadjacent to the gastric epithelium and in the smooth muscle layers of both the small and large intestine. Only the small intestine showed (-)-3-[2-hydroxyl-4-(1,1-dimethylheptyl)-phenyl]-4-(3-hydroxylpropyl) cyclohexan-1-ol) ([3H]CP 55,940) specific binding (27%). These receptors mediated pharmacologically significant effects since the cannabinoid CB(1) receptor agonist R(-)-7-hydroxy-delta-6-tetra-hydrocannabinol-dimethylheptyl (HU 210) dose dependently inhibited gastrointestinal transit up to 70%, while the cannabinoid CB(1) receptor antagonist N-piperidino-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methylpyrazole-3-carboxamide (SR 141716A) increased gastrointestinal transit. Moreover, the dose of 0.3 microg/kg of HU 210, devoid per se of any activity on mouse intestinal propulsion, blocked the increased gastroenteric transit induced by the cannabinoid CB(1) antagonist SR 141716A.

Reduction in both presynaptic and postsynaptic structures in the aging neocortex may significantly affect functional synaptic properties in this area. To directly address this issue, we combined whole-cell patch-clamp recording of spontaneously occurring postsynaptic currents (PSCs) with morphological analysis of layer V pyramidal neurons in the parietal cortex of young adult (1- to 2-month-old) and aged (28- to 37-month-old) BNxF344 F1hybrid rats. Analysis of spontaneous PSCs was used to contrast functional properties of basal synaptic input with structural alterations in the dendritic tree of pyramidal neurons and density of terminals in contact with these cells.We observed significant changes in a number of morphological parameters of pyramidal neurons in aged rats. These include smaller cell body size and fewer basal dendritic branches (but not of oblique dendrites and dendritic tufts) and spines. Ultrastructural analysis also revealed a lower density of presynaptic terminals per unit length of postsynaptic membrane of labeled pyramidal neurons in the aged brain. This reduction in both presynaptic and postsynaptic elements was paralleled by a significant decrease in frequency of tetrodotoxin-insensitive miniature (action potential-independent) PSCs (mPSCs). The frequency of excitatory and inhibitory mPSCs was reduced to the same extent. In contrast, no significant change was observed in the frequency of spontaneous PSCs recorded in absence of tetrodotoxin (sPSCs), indicating an increase in action potential-dependent (frequencysPSCs− frequencymPSCs) input to pyramidal neurons in the aged group. This functional compensation may explain the lack of drastic loss of spontaneous neuronal activity in normal aging.

SummaryDopamine is implicated in the pathogenesis of both the positive and the negative symptoms of schizophrenia. Clinical efficacy of antipsychotic drugs, without the production of side-effects, may be achieved by a dose–response separation of pharmacological function, regional (i.e., anatomical) selectivity of action, or by the selective targeting of neuroreceptors. The atypical antipsychotics have many different ways of acting on receptors in the brain, but they have in common a decreased likelihood of producing extrapyramidal side-effects. Patients respond well to them by showing improvements of both positive and negative symptoms. The preclinical profile of amisulpride shows specificity for D2/D3 dopamine receptors and selective activity in the limbic system. There is evidence that amisulpride is effective in treating both the negative and positive symptoms of schizophrenia, and that it has a low propensity to induce motor side-effects. Therefore, both positive and negative symptoms can be treated, without inducing these side-effects, by selectively targeting dopamine receptors.

INTRODUCTION: Controlled-release formulations of atypical antipsychotics have recently been introduced into clinical practice. Clinical studies have indicated that these new therapies induce meaningful improvements in the functioning and quality of life of schizophrenic individuals. AREAS COVERED: The present analysis makes an attempt to address the clinical relevance of these studies and their contribution to the understanding of the mechanisms of action of these new drugs. A Medline search was done using the keywords 'antipsychotic', 'plasma level', 'quality of life' and 'functioning'. EXPERT OPINION: After reviewing the literature, it seems that symptom control and side effects may play a role in modulating the functioning and quality of life of schizophrenic individuals treated with controlled-release formulations of atypical antipsychotics. The analysis also highlights that these new drugs may possess peculiarities and similarities in regulating patient functioning. However, the low number of clinical analyses that have focused on these aspects of antipsychotic therapy limits the interpretation of the results. Additional comparative clinical trials are needed to evaluate how the pharmacokinetic/pharmacodynamic properties of antipsychotic drugs may modulate the functioning and quality of life of schizophrenic individuals, as well as to establish whether new clinical benefits may come from the use of these drugs in schizophrenia therapy.

It is proposed that to achieve a therapeutic effect in schizophrenia patients, dopamine D2-receptor occupancy by antipsychotics within the striatum must exceed 60−65%. However, at high levels of D2-receptor occupancy, the risk of extrapyramidal symptoms (EPS) is increased. Following oral dosing of antipsychotics, peaks and troughs in plasma drug concentrations may be mirrored by fluctuations in D2-receptor occupancy. Paliperidone, a novel antipsychotic available as extended-release tablets (paliperidone ER), is the major active metabolite of risperidone and exhibits a plasma pharmacokinetic profile with reduced peak−trough fluctuations and consistent D2-receptor occupancy compared with conventional oral antipsychotic formulations. Using formulations that resemble those in clinical practice, this study provides a preclinical evaluation of the pharmacological properties of paliperidone ER and risperidone immediate-release formulation in terms of consistent antipsychotic efficacy over time and extrapyramidal symptom liability. Significant fluctuations in inhibition of d-amphetamine-induced hyperlocomotion were observed for repeated subcutaneous (SC) risperidone injections, whereas stable inhibitory efficacy was demonstrated during continuous SC paliperidone infusion. Similarly, significant fluctuations in latency on-bar were observed with repeated SC risperidone injections, whereas significantly lower latency on-bar was demonstrated following continuous SC paliperidone infusion. These results in an animal model suggest that although risperidone and paliperidone demonstrate similar pharmacologic effects, continuous administration of paliperidone achieves more stable antipsychotic efficacy with reduced motor impairment, akin to the effects observed with paliperidone ER in clinical studies.

Delta(9)-Tetrahydrocannabinol (Delta(9)-THC), the major psychoactive constituent of Cannabis sativa L., has been widely studied for its potential pharmaceutical application in the treatment of various diseases and disturbs. This sparingly soluble terpeno-phenolic compound is not easy to handle and to be formulated in pharmaceutical preparations. The aim of this work was to develop a stable aqueous Delta(9)-THC formulation acceptable for different ways of administration, and to evaluate the therapeutic properties of the new Delta(9)-THC based preparation for pain treatment. Due to the thermodynamic stability and advantages of microemulsion based systems, the study was focused on the identification of aqueous microemulsion based systems containing Delta(9)-THC. Oil in water Delta(9)-THC microemulsions were individuated through phase diagrams construction, using the non-ionic surfactant Solutol HS15, being this surfactant acceptable for parenteral administration in human. A selected microemulsion samples containing 0.2 wt% of Delta(9)-THC, stable up to 52 degrees C, was successfully assayed on animal models of pain. Significant antinociceptive activity has been detected by both intraperitoneal and intragastric administration of the new Delta(9)-THC pharmaceutical preparation. The effect has been highlighted in shorter time if compared to a preparation of the same active principle based on previously reported conventional preparation.

Background: The development of paliperidone extended release (ER) may represent a new strategy to improve the pharmacological treatment of schizophrenia. The drug maintains the atypical antipsychotic profile of its parent compound risperidone, but it is associated with an innovative delivery system (OROS technology) that offers the possibility to obtain smooth drug plasma levels using an oral antipsychotic. Clinical trials confirmed that paliperidone ER is efficacious in the management of schizophrenia and well tolerated, however no direct clinical comparisons between paliperidone ER and immediate-release formulations of risperidone have been conducted to date. Objective: The present study evaluates possible differences between paliperidone ER and immediate-release formulations of risperidone due to structural/molecular and delivery system diversities, providing an estimation of their significance in the context of clinical results. Methods: A search of Medline and EMBASE was performed using the keywords 'Risperidone', 'Paliperidone' and 'OROS technology'. Results/conclusion: The analysis suggests that the chemical structure and pharmacokinetic profile of paliperidone ER might provide clinical benefits in terms of efficacy, tolerability and more consistent drug response among patients, when compared with the parent compound risperidone in its immediate release formulations. The relevance of these differences is discussed, taking into account several clinical aspects involved in the drug therapy of schizophrenia. © 2009 Informa UK Ltd All rights reserved.

It has been proposed that long-acting risperidone could provide a constant antipsychotic efficacy associated with a reduced liability to induce extra-pyramidal symptoms. To ascertain this hypothesis, antagonism of amphetamine-induced hyperlocomotion and catalepsy were analyzed in rats for a period of 1-6 weeks following long-acting risperidone (20-60 mg/kg) injection. Long-acting risperidone reduced amphetamine-induced hyperlocomotion after 2-5 weeks from drug injection, without producing significant extra-pyramidal symptoms. Following the administration of long-acting risperidone a constant ability to antagonize amphetamine-induced hyperlocomotion was observed during the day, but not when the antipsychotic was chronically administered using a short-acting formulation. The pre-clinical results confirmed that long-acting risperidone may represent an advance in antipsychotic therapy.

It was previously shown that haloperidol, but not clozapine, induced intense rat catalepsy when co-administered with delta-9-tetrahydrocannabinol. The present study investigated whether similar alterations could be observed on striatal c-Fos immunoreactivity after administration of the same drug combinations. Western Blot and immunocytochemistry stereological analyses indicated that delta-9-tetrahydrocannabinol (0.5 mg/kg) increased striatal c-Fos immunoreactivity induced by haloperidol (0.1 mg/kg). Conversely, no significant alterations of striatal c-Fos immunoreactivity were observed after injections of clozapine (10 mg/kg) + vehicle, clozapine + delta-9-tetrahydrocannabinol or vehicle + delta-9-tetrahydrocannabinol. The present results indicate that the behavioral effects induced by delta-9-tetrahydrocannabinol in haloperidol- and clozapine-treated rats are associated with different striatal c-Fos expressions.

Clinically important differences exist between antipsychotic agents and formulations in terms of safety and tolerability. Features of the biochemical interaction between the antipsychotic and the D2-receptor may underlie these differences. This article reviews current information on the relationship between antipsychotic receptor occupancy and clinical response. A literature search was performed using the keywords ‘antipsychotic or neuroleptic’, ‘receptor’ and ‘occupancy’ and ‘dopamine’ and ‘D2’ supplemented by the authors’ knowledge of the literature. Imaging and clinical data have generally supported the hypotheses that optimal D2-receptor occupancy in the striatum lies in a ‘therapeutic window’ between ∼65 and ∼80%, however, pharmacokinetic and pharmacodynamic properties of a drug should also be taken into account to fully evaluate its therapeutic effects. Additional research, perhaps in preclinical models, is needed to establish D2-receptor occupancy in various regions of the brain and the optimal duration of D2-receptor blockade in order to maximise efficacy and tolerability profiles of atypical antipsychotics and thereby improve treatment outcomes for patients with schizophrenia.

The number of synapses in the cerebral cortex decreases with aging. However, how this structural change translates into the cognitive impairment observed in aged animals remains unknown. Aged animals are not a homogenous group with respect to their cognitive performances; but instead, they can be separated into aged cognitively unimpaired ("normal") and aged cognitively impaired groups using a spatial memory task such as the Morris water maze. These two aged groups provide an unprecedented opportunity to isolate synaptic properties that relate to cognitive impairment from unrelated factors associated with normal aging. Using such classification, we conducted whole-cell patch-clamp recordings to measure basal spontaneous miniature excitatory (mEPSCs) and inhibitory synaptic currents (mIPSCs) bombarding layer V pyramidal neurons in the parietal cortex. We found that the frequencies of both mEPSC and mIPSC were lower in aged normal rats when compared with young rats. In contrast, aged cognitively impaired rats displayed a reduction in mEPSC frequency only. This results in an imbalance towards inhibition that may be an important substrate of the cognitive impairment in aged animals. We also found that pyramidal neurons in both aged normal and aged cognitively impaired rats exhibit similar structural attritions. Thus, cognitive impairment may be more related to an altered balance between different neurotransmitter systems than a mere reduction in synaptic structures.

The effect of two alpha-adrenergic receptor antagonists widely employed in the therapy of benign prostatic hyperplasia, tamsulosin [(-)-(R)-5-[2-[[2-(0-ethoxyphenoxy) ethyl]amino]propyl]-2-methoxybenzenesulfonamide] and alfuzosin [(+/-)-N-[3-[(4-amino-6,7-dimethoxy-2-quinazolinyl) methylamino]propyl] tetrahydro-2-furancarboxamide], was investigated in the rat vas deferens. Because several clinical studies have shown that tamsulosin causes ejaculatory disorders, this study also evaluated the possible mechanisms implicated in these disorders by comparing the effect of tamsulosin with that of alfuzosin. Tamsulosin competitively antagonized the contractions induced by noradrenaline in vitro in the epididymal portion of the vas deferens with a potency pA(2) value of 9.2 +/- 0.8. In the prostatic portion, tamsulosin increased the amplitude of intermittent spikes induced by exogenous noradrenaline (100-1000 microM). In both portions of the vas deferens, alfuzosin behaved as an alpha-adrenergic antagonist blocking the contractions induced by exogenous noradrenaline without altering spikes. The administration of tamsulosin (3 microg/kg i.v.) significantly reduced the contractions evoked by electrical pulses in the epididymal portion, whereas it increased those produced in the prostatic portion. Intravenous tamsulosin antagonized the contraction produced by exogenous noradrenaline, whereas alfuzosin administration (10 microg/kg i.v.) did not change the electrically induced contractions in both portions of the rat vas deferens and did not antagonize the contractions produced by exogenous noradrenaline. The fact that tamsulosin unusually enhances noradrenaline-induced intermittent spike contractions and nerve stimulation-induced twitches in the prostatic portions might be linked to its greater propensity to cause sexual dysfunctions.

Sardinian alcohol non-preferring (sNP) rats carry a point mutation (R100Q) in the cerebellar expressed GABAA receptor alpha6 subunit gene, leading to a higher sensitivity to ethanol and diazepam. The role of the alpha6 subunit gene cluster in the ethanol non-preferring phenotype was here investigated by measuring the levels of alpha1, alpha6 and gamma2 peptide in the cerebellum of normal (RR) and mutated (QQ) sNP rats after 2 weeks of chronic ethanol administration. Western blot analysis revealed that the alpha6 subunit is increased in RR sNP rats after chronic ethanol exposure (25.44%+/-8.69 versus control), while it remained unchanged in mutated QQ sNP rats. Interestingly, chronic ethanol administration decreased alpha1 peptide levels in the cerebellum of both rat lines to a similar extent (30.99%+/-6.74 and 27.12%+/-9.83 in RR and QQ rats, respectively), while gamma2 peptide levels remained unchanged. To further correlate the genetic and biochemical difference of the normal and mutated sNP rats with their aversive phenotype, we exposed sNP rats to a protocol of acquisition and maintenance of ethanol drinking. QQ sNP rats drank less ethanol than RR rats during the acquisition phase, but such difference was lost during the maintenance phase. These data may contribute to elucidating the mechanisms of alcohol avoidance in rat lines selected for this behavior when exposed to ethanol solution.

The effect of subchronic co-administration of ritanserin (1.5 mg/kg, i.p., twice a day) and haloperidol (1 mg/kg, i.p., twice a day) on rat vacuous chewing movements and on tyrosine hydroxylase-immunostaining was investigated. Ritanserin significantly reduced rat vacuous chewing movements observed following 2, 3 and 4 weeks of haloperidol administration and after 5 days of haloperidol withdrawal. Furthermore, ritanserin prevented the reduction of striatal tyrosine hydroxylase-immunostaining and the shrinkage of nigral dopaminergic cell bodies induced by haloperidol. The present results indicate that ritanserin may possess protective properties on both dopaminergic nigro-striatal neuron alterations and vacuous chewing movements induced by haloperidol, and provide further evidence indicating a possible association between these two haloperidol-induced effects.

Antipsychotic drug treatment increases neurotensin (NT) neurotransmission, and the exogenous administration of NT produces antipsychotic-like effects in rodents. In order to investigate whether “endogenous” NT may act as a natural occurring antipsychotic or may mediate antipsychotic drug activity, the effects of the selective NT receptor antagonists SR 48692 and SR 142948A were analyzed in different behavioural tests of locomotor activity using vehicle, amphetamine, or haloperidol in mice. SR 48692 (0.1–1 mg/kg, i.p.) and SR 142948A (0.03–0.1 mg/kg, i.p.) failed to affect mouse spontaneous locomotor activity and amphetamine-induced (2.5 mg/kg, i.p.) hyper-locomotion. However, SR 48692 (0.1 and 0.3 mg/kg, i.p.) and SR 142948A (0.03 and 0.05 mg/kg, i.p.) significantly alleviated the reduction of locomotor activity elicited by haloperidol (0.01 and 0.04 mg/kg, s.c.) in vehicle- or amphetamine-treated mice. Finally, SR 48692 (0.3 mg/kg, i.p.) and SR 142948A (0.05 and 0.1 mg/kg, i.p.) increased mouse catalepsy produced by haloperidol (0.3 mg/kg, s.c.). The present results indicate that while endogenous NT is not involved in the modulation of either mouse spontaneous locomotor activity or amphetamine-induced hyper-locomotion, it might act by enhancing the therapeutic effects of haloperidol and by attenuating the extrapyramidal side effects elicited by this antipsychotic.

The compound N-piperidinyl-[8-chloro-1-(2,4-dichlorophenyl)-1,4,5,6-tetrahydrobenzo [6,7]cyclohepta[1,2-c]pyrazole-3-carboxamide] (NESS 0327) was synthesized and evaluated for binding affinity toward cannabinoid CB1 and CB2 receptor. NESS 0327 exhibited a stronger selectivity for CB1 receptor compared with N-piperidinyl-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide (SR 141716A), showing a much higher affinity for CB1 receptor (Ki = 350 +/- 5 fM and 1.8 +/- 0.075 nM, respectively) and a higher affinity for the CB2 receptor (Ki = 21 +/- 0.5 nM and 514 +/- 30 nM, respectively). Affinity ratios demonstrated that NESS 0327 was more than 60,000-fold selective for the CB1 receptor, whereas SR 141716A only 285-fold. NESS 0327 alone did not produce concentration-dependent stimulation of guanosine 5'-O-(3-[35S]thio)-triphosphate ([35S]GTPgammaS) binding in rat cerebella membranes. Conversely, NESS 0327 antagonized [R(+)-[2,3-dihydro-5-methyl-3-[(morpholinyl)methyl]pyrolol [1,2,3-de]-1,4-benzoxazin-yl]-(1-naphthalenyl)methanone mesylate] (WIN 55,212-2)-stimulated [35S]GTPgammaS binding. In functional assay, NESS 0327 antagonized the inhibitory effects of WIN 55,212-2 on electrically evoked contractions in mouse isolated vas deferens preparations with pA2 value of 12.46 +/- 0.23. In vivo studies indicated that NESS 0327 antagonized the antinociceptive effect produced by WIN 55,212-2 (2 mg/kg s.c.) in both tail-flick (ID50 = 0.042 +/- 0.01 mg/kg i.p.) and hot-plate test (ID50 = 0.018 +/- 0.006 mg/kg i.p.). These results indicated that NESS 0327 is a novel cannabinoid antagonist with high selectivity for the cannabinoid CB1 receptor.

Sardinian alcohol non-preferring (sNP) rats, selected for their low ethanol preference and consumption, carry a point mutation (R100Q) in the gene coding for GABA(A) receptor alpha(6) subunit, which becomes more sensitive to diazepam-evoked GABA currents. We performed binding studies in the cerebellum of normal (RR) and mutated (QQ) sNP rats using [3H]Ro 15-4513, an inverse agonist for the benzodiazepine site which binds both diazepam insensitive and diazepam sensitive sites. Saturation curves performed on cerebellar membrane from genotyped rats indicated an higher affinity of [3H]Ro 15-4513 for GABA(A) receptors in QQ with respect to RR rats (K(d) values 4.0+/-0.67 and 6.24+/-0.95 nM, respectively), with similar B(max) values (3.5+/-0.25 and 3.9+/-0.39 pmol/mg protein, respectively). Diazepam displacement curves showed a two component model for both genotypes, with similar K(i1) values for QQ and RR (3.6+/-0.62 and 4.9+/-0.33 nM, respectively). In QQ rats diazepam is able to completely displace [3H]Ro 15-4513 (K(i2)=1.48+/-0.27 microM), while in RR rats the diazepam sensitive sites are still present (K(i2)10 microM). The basal mRNA and protein expression level of the alpha(6) subunit were similar in RR and QQ rats. The electrophysiological profile of oocytes of Xenopus laevis injected with cerebellar synaptosomes showed that ethanol positively modulated GABA-evoked currents significantly more in QQ than in RR rats. These data contribute to the characterization of the function of GABA(A) alpha(6) subunit and its involvement in determining alcohol related behavior.

OBJECTIVE: Previous reports have shown that the Delta(9)-tetrahydrocannabinol (Delta(9)TCH), the major psychoactive cannabinoid components of marijuana, is able [corrected] to inhibit thyroid hormonal activity. The aim of this study was to characterize the CB1 functional expression in the rat thyroid by a multi-methods approach. METHODS AND RESULTS: RT-PCR was used to detect the mRNA expression of the CB1 cannabinoid receptor (17.8+/-4.0% of the normalizing reference gene beta(2) microglobulin), as well as the expression of the endocannabinoid hydrolyzing enzyme, fatty acid amide hydrolase (46.9+/-4.3% of beta(2) microglobulin), in the rat thyroid gland. The CB1-encoded protein was detected in its glycosylated form (63 kDa) by Western blot, employing a polyclonal antibody, while CB1 immunohistochemical localization showed an intracellular positive staining in both follicular and parafollicular cells. In addition, a 30% decrease in serum levels of both 3,5,3' tri-iodothyronine (T(3)) and thyroxine (T(4)) was detected 4 h after the administration of the synthetic cannabinoid receptor agonist, WIN 55,212-2 (10 mg/kg i.p.). These effects were antagonized by pretreatment with the CB1 antagonist SR 141716A (3 mg/kg i.p.); thyrotrophin levels were unaffected by both treatments. CONCLUSION: These data indicate that functional CB1 receptors which are able to modulate the release of T(3) and T(4) are expressed in the rat thyroid, and suggest a possible role of cannabinoids in the regulation of rat thyroid hormonal activity.

The effects on rat serum prolactin level of the two isomers constituting the racemic form of amisulpride were compared. (S-)-amisulpride induced hyperprolactinemia at lower doses (ED(50) = 0.09 +/- 0.01 mg/kg) than racemic- (ED(50) = 0.24 +/- 0.03 mg/kg) and (R+)-amisulpride (ED(50) = 4.13 +/- 0.05 mg/kg), in accord with their affinities for pituitary dopamine D(2) receptor (K(i) = 3.8 +/- 0.2, 6.4 +/- 0.2 and 143.3 +/- 2.3 nM, respectively). At doses twice the ED(50), (S-)-amisulpride produced a maximal increase in prolactin level similar to that of the racemic form (403 +/- 21% and 425 +/- 15%, respectively), but higher than that of (R+)-amisulpride (198 +/- 8%). These results suggest that the hyperprolactinemia induced by the racemic-amisulpride is mostly due to its (S-)-isomer.

The substituted benzamide amisulpride is currently administered in its racemic form. In the present study, the biochemical and cataleptogenic profiles of the two enantiomers (R+ and S-) were compared with those of the racemic mixture. Displacement binding studies showed that the (S-)-isomer possesses an higher affinity for dopamine D2-like receptor (K(i) 5.2+/-0.4 nM) compared to (R+)-amisulpride (K(i) 244+/-12 nM) and to (RS)-amisulpride (K(i) 9.8+/-0.8 nM). In contrast, (S-)-amisulpride binds the alpha(2)-receptor with an affinity (K(i) 1528+/-45 nM) lower than that of the (R+)-isomer (K(i) 375+/-34 nM) and of (RS)-amisulpride (K(i) 783+/-27 nM). The bar test was used to evaluate the catalepsy induced by each drug. (RS)-amisulpride induced catalepsy only at very high doses (>100 mg/kg, s.c.) whereas, (S-)-amisulpride produced a catalepsy at a lower dose (30 mg/kg, s.c.) and (R+)-amisulpride did not produce any catalepsy up to the dose of 75 mg/kg. Interestingly, (R+)-amisulpride reduced the catalepsy induced by (S-)-amisulpride (50 mg/kg, s.c.) or haloperidol (0.3 mg/kg, s.c.), at the doses of 50 or 30 mg/kg, respectively. These results indicate that the weak cataleptic properties of (RS)-amisulpride might partially rely on its (R+)-isomer and provide a further explanation for the atypical properties of amisulpride as an antipsychotic.

Prolactin blood level and apomorphine-induced yawning were studied in rats treated with the substituted benzamide amisulpride in association with bromocriptine or carmoxirole; two dopamine D 2 receptor agonists with high or low propensity to cross the brain–blood barrier, respectively. Administration of amisulpride produced a maximum increase in rat serum prolactin level (315±18%) vs. vehicle-treated animals (ED 50 =0.25±0.017 mg/kg, s.c.). The concurrent administration of carmoxirole or bromocriptine completely reversed the hyperprolactinemia induced by amisulpride (0.5 mg/kg, s.c.) (ID 50 =14.9±0.8 mg/kg and 0.81±0.03 mg/kg, respectively). Carmoxirole (15 mg/kg, i.p.) did not affect yawning induced by apomorphine (0.08 mg/kg, s.c.) nor amisulpride (0.5 mg/kg, s.c.) blockade of apomorphine-induced yawning. Conversely, a significant increase in the number of yawns was observed when bromocriptine (0.8 mg/kg, i.p.) was associated with apomorphine in the absence or presence of amisulpride. These results suggested that a peripheral dopamine D 2 receptor agonists could be a useful tool in alleviating amisulpride-induced hyperprolactinemia without possibly affecting its central effect.

Sara Piras, Gianluca Casu, Maria Antonietta Casu, Alessandro Orrù, Stefania Ruiu, Antonio Pilleri, Gabriella Manca, Giorgio MarcheseNational Research Council, Institute of Translational Pharmacology, Strategic Operating Unit of Cagliari, Cagliari, ItalyAbstract: In the last few decades, substantial research has focused on the possibility of early detection and prevention of the first psychotic episode in young individuals at risk of developing this mental disturbance; however, unresolved clinical and ethical issues still call for further investigations. New perspectives and opportunities may come from the identification of selective psychopathological and instrumental markers linking the appearance of subtle psychotic symptoms with the clinical outcome of specific mental pathologies. Furthermore, empirically derived algorithms and risk staging models should facilitate the identification of targeted prevention therapies, possibly improving the efficacy of well-tolerated therapeutic approaches, such as psychological interventions and natural compound supplementations. To date, the collected evidence on the efficacy and tolerability of pharmacological prevention therapies raises more doubts than hopes. A very early detection of risk and appropriate symptomatic pattern classifications may provide a chance to better match prevention strategies with the development of psychosis.Keywords: psychosis, risk, basic symptoms, schizophrenia, therapy

Specific gamma-hydroxybutyric acid (GHB) binding sites in cortical membranes of selectively bred alcohol-preferring sP and alcohol-non preferring sNP rats were compared using [2,33H]GHB ligand. The sP rat line showed an increased affinity (-40% lower Kd) of both the high- and low-affinity sites in comparison with the sNP line. No significant difference in GHB receptor density ( B max) was detected between the two rat lines. The results raise the possibility that differences in GHB binding sites may play a role in the genetic predisposition to ethanol preference in our rat line.

The effect of ritanserin on dopamine (DA) re-uptake and efflux was studied in rat frontal cortex synaptosomes. When compared to other 5HT2 receptor antagonists such as ketanserin and risperidone or DA D2 receptor antagonists such as haloperidol and raclopride, the effect of ritanserin proved to be more potent. Ritanserin blocked the DA transporter with a Ki of 0.18 +/- 0.06 microM, similar to cocaine (0.11 +/- 0.005 microM), while ketanserin had a Ki of 0.93 +/- 0.045; haloperidol of 2.07 +/- 0.12; risperidone of 18.01 +/- 0.62 and raclopride of 24.01 +/- 1.55. In addition, 15 min from its local application to the synaptosomes, ritanserin potently released [3]H-DA leaving only 29.6 +/- 1.6% of DA content, while ketanserin effect was equal to 46.5 +/- 0.9%; haloperidol to 70.4 +/- 2.2% and risperidone to 73.9 +/- 1.5%, all tested at the dose of 10 microM. Cocaine had no effect on DA efflux. These results suggest that ritanserin has a intrinsic dopaminergic effect which may help to explain its reported improvement on mood, cognition and negative symptoms of schizophrenia.