Comparative Pharmacology of Risperidone and Paliperidone.

Antipsychotics, risperidone, and risperidone's active metabolite, paliperidone (9-hydroxyrisperidone), are related molecules used for the treatment of schizophrenia and related disorders. Differences in receptor binding, 5-HT2A/D2 (serotonin/dopamine) binding ratios, and mitochondrial proteomics suggest that the effects of risperidone and paliperidone on neuronal firing, regulation of mitochondrial function, and movement are different. This review seeks to explore the most significant differences at the molecular level between risperidone and paliperidone, as reported in preclinical studies. Although risperidone shows higher affinity for 5-HT receptors, paliperidone does not fit this profile. Thus, the risperidone 5-HT2A/D2 binding ratio is significantly lower than the paliperidone 5-HT2A/D2 binding ratio. Paliperidone, similar to lithium and valproate, affects expression levels and phosphorylation of complex I and V proteins in synaptoneurosomal preparations of rat prefrontal cortex, suggesting that paliperidone behaves as a mood stabilizer. It is apparent that the presence of a hydroxyl group in the paliperidone molecule confers increased hydrophilicity to this drug compared with its parent, risperidone; thus, this contributes to differential effects on mitochondrial movement, protein expression, and phosphorylation. These differences are reflected in synaptic plasticity and neuronal firing and have only recently been implicated in the mechanisms of mitochondrial function and movement.

New model of action for mood stabilizers: phosphoproteome from rat pre-frontal cortex synaptoneurosomal preparations.

BACKGROUND: Mitochondrial short and long-range movements are necessary to generate the energy needed for synaptic signaling and plasticity. Therefore, an effective mechanism to transport and anchor mitochondria to pre- and post-synaptic terminals is as important as functional mitochondria in neuronal firing. Mitochondrial movement range is regulated by phosphorylation of cytoskeletal and motor proteins in addition to changes in mitochondrial membrane potential. Movement direction is regulated by serotonin and dopamine levels. However, data on mitochondrial movement defects and their involvement in defective signaling and neuroplasticity in relationship with mood disorders is scarce. We have previously reported the effects of lithium, valproate and a new antipsychotic, paliperidone on protein expression levels at the synaptic level. HYPOTHESIS: Mitochondrial function defects have recently been implicated in schizophrenia and bipolar disorder. We postulate that mood stabilizer treatment has a profound effect on mitochondrial function, synaptic plasticity, mitochondrial migration and direction of movement. METHODS: Synaptoneurosomal preparations from rat pre-frontal cortex were obtained after 28 daily intraperitoneal injections of lithium, valproate and paliperidone. Phosphorylated proteins were identified using 2D-DIGE and nano LC-ESI tandem mass spectrometry. RESULTS: Lithium, valproate and paliperidone had a substantial and common effect on the phosphorylation state of specific actin, tubulin and myosin isoforms as well as other proteins associated with neurofilaments. Furthermore, different subunits from complex III and V of the electron transfer chain were heavily phosphorylated by treatment with these drugs indicating selective phosphorylation. CONCLUSIONS: Mood stabilizers have an effect on mitochondrial function, mitochondrial movement and the direction of this movement. The implications of these findings will contribute to novel insights regarding clinical treatment and the mode of action of these drugs.

Sensorimotor gating in NTS1 and NTS2 null mice: effects of d-amphetamine, dizocilpine, clozapine and NT69L.

Pre-pulse inhibition (PPI) of the acoustic startle reflex is deficient in patients with schizophrenia. This deficiency is mimicked in mice by the use of the psychotomimetic drugs d-amphetamine and dizolcipine. Antipsychotic drugs such as clozapine are used to treat schizophrenic patients and are also administered to mice to prevent PPI disruption. Neurotensin (NT) produces antipsychotic-like effects when injected into rodent brain through its effects at NT subtype 1 (NTS1) and 2 (NTS2) receptors. We hypothesized that the NT receptor agonist (NT69L) would prevent PPI disruption in mice challenged with d-amphetamine (10 mg kg(-1)) and dizocilpine (1 mg kg(-1)). We investigated the role of NTS1 and NTS2 in PPI using wild-type (WT), NTS1 (NTS1(-/-)) and NTS2 (NTS2(-/-)) knockout mice, via its disruption by psychotomimetic drugs, as well as the ability of clozapine and NT69L to block these PPI disruptions. There were no differences in baseline PPI across the three genotypes. d-Amphetamine and dizocilpine disrupted PPI in WT and NTS2(-/-) mice but not in NTS1(-/-) mice. In WT mice, clozapine (1 mg kg(-1)) and NT69L (1 mg kg(-1)) significantly blocked d-amphetamine-induced disruption of PPI. Similarly, in WT mice, clozapine significantly blocked dizocilpine-induced PPI disruption, but NT69L did not. In NTS2(-/-) mice clozapine blocked d-amphetamine-but not dizocilpine-induced PPI disruption, while NT69L blocked both d-amphetamine- and dizocilpine-induced PPI disruption. Our results indicate that NTS1 seems essential for d-amphetamine and dizocilpine disruption of PPI. Additionally, this report provides support to the hypothesis that NT analogs could be used as novel antipsychotic drugs.

ANHIDRASA CARBÓNICA DE Plasmodium falciparum: UN BLANCO ÚTIL PARA EL DISEÑO DE MEDICAMENTOS ANTIMALÁRICOS Y COMPUESTOS BLOQUEADORES DE LA TRANSMISIÓN DE MALARIA / CARBONIC ANHYDRASE IN Plasmodium falciparum: A USEFUL TARGET FOR ANTIMALARIAL DRUG DESIGNING AND MALARIA BLOCKING TRANSMISSION COMPOUNDS

La anhidrasa carbónica es una metaloenzima que cataliza la conversión reversible del CO2 a bicarbonato, un componente metabólico indispensable para la síntesis de pirimidinas de novo por Plasmodium spp y los procesos de exflagelación llevados a cabo por el parásito al interior del mosquito vector. La enzima participa además en el transporte del bicarbonato dentro y fuera de las células para evitar un desequilibrio en el sistema CO2/HCO3- y la alteración del pH al interior de las células y en el espacio intercelular. Por lo tanto, al inhibir la enzima, ya sea en el parásito o en el insecto vector, se podría conducir a una disminución de la replicación y al detrimento y/o muerte del parásito. De esta forma, los inhibidores de anhidrasa carbónica constituyen una alternativa, tanto terapéutica como de bloqueo de la transmisión, para el control de la malaria. La actividad anti-Plasmodium in vitro de algunos compuestos inhibidores de anhidrasa carbónica ya se ha determinado. Sin embargo, la eficacia in vivo y el mecanismo por el cual los inhibidores son capaces de afectar el desarrollo del parásito en los mosquitos vectores permanecen aún por evaluarse. En el marco del proyecto de investigación "Evaluación de inhibidores de anhidrasa carbónica como medidas terapéuticas y de bloqueo de la transmisión de malaria" este artículo presenta una revisión del estado del arte sobre el papel de la anhidrasa carbónica de Plasmodium spp y el uso de inhibidores específicos de esta enzima como una estrategia para el tratamiento de la malaria y el bloqueo de la transmisión de la enfermedad. Se incluyeron artículos publicados en los últimos 59 años, identificados a partir de la bases de datos bibliográficos PubMed y ScienceDirect, cruzando las palabras claves, al igual que artículos recopilados por los autores y se analizan e integran los resultados de investigaciones publicadas alrededor del tema.

Carbonic anhydrase is a metalloenzyme that catalyzes the reversible conversion of CO2 to bicarbonate, an essential metabolic component used by the malaria parasites for de novo synthesis of pyrimidines and the exflagelation of gametocytes inside the mosquito vector. Carbonic anhydrase is involved in the transport of bicarbonate. This enzyme participates in transport of bicarbonate inside and outside the cells to avoid an imbalance in the system CO2/HCO3- and alteration of pH in the interior of the cell as well as in the intercellular space. Therefore, inhibition of this enzyme either in the parasite or the insect vector, could lead to a decrease in replication and to the detriment and/or death of the parasite. Given the importance of carbonic anhydrase in the metabolism, development and survival of Plasmodium, it could be postulated that carbonic anhydrase inhibitors are both a therapeutic and a blocking transmission alternative. Previous studies have demonstrated the in vitro anti-Plasmodium activity of some inhibitors. However, it is necessary to determine their effectiveness to confirm its usefulness in the treatment or blocking malaria transmission and the mechanism by which these inhibitors are able to affect the development of the parasite in the mosquito vector. In this paper we present a review about the role of carbonic anhydrase in Plasmodium spp and using some specific inhibitors as a strategy for malaria treatment and transmission blocking strategy. Articles published in the past 59 years identified from bibliographic database (PubMed and ScienceDirect) and papers collected by the authors were included.

Paliperidone as a mood stabilizer: a pre-frontal cortex synaptoneurosomal proteomics comparison with lithium and valproic acid after chronic treatment reveals similarities in protein expression.

A series of recent studies has demonstrated that the molecules involved in regulation of neuronal plasticity are also involved in the mode of action of antidepressants and mood stabilizer drugs. Intracellular calcium signaling, energy metabolism, and neuronal plasticity can be influenced by inducing axonal remodeling and increasing levels of certain synaptic proteins. Because antipsychotic drugs are used as mood stabilizers our studies focused on a newly-marketed antipsychotic drug, paliperidone. We determined changes in rat synaptoneurosomal proteins after chronic treatment with paliperidone, lithium salt, or valproic acid in order to find similarities or differences between the mode of action of paliperidone and these two classical mood stabilizers. We determined differential protein expression profiles in prefrontal cortex (PFC) of male Sprague-Dawley rats (n = 4/group). Synaptoneurosomal-enriched preparations were obtained from PFC after chronic treatment with these three drugs. Proteins were separated by 2D-DIGE and identified by nano-LC-MS/MS. We observed similar protein expression profiles at the synaptoneurosomal level, suggesting that the mode of action for paliperidone is similar to that of lithium and valproic acid. However, the expression profile for paliperidone was more similar to that of lithium. Pathways affected in common by these two drugs included oxidative phosphorylation, electron transport, carbohydrate metabolism, and post-synaptic cytokinesis implicating the effects of these drugs in signaling pathways, energy metabolism, and synaptic plasticity.