Central benzodiazepine receptor imaging and quantitation with single photon emission computerised tomography: SPECT

Brain uptake of iomazenil in cirrhotic patients: a single photon emission tomography study

Brain uptake of 123I-iomazenil was studied in seven cirrhotic patients and eight normal controls using single photon emission computerized tomography. The highest concentration of the ligand was found in the occipital cortex, which corresponds to the brain region with the highest concentration of benzodiazepine receptors. The peak uptake was delayed in patients across all brain regions. The uptake in occipital cortex was higher in low albumin cirrhotics. Patients with low albumin also presented a more delayed peak uptake in occipital cortex and a higher volume of distribution of iomazenil in plasma, compared to patients with normal albumin levels and controls. The changes in brain uptake (delayed peak uptake and increased maximal uptake in occipital cortex) appears to reflect changes in the pharmacokinetics of the ligand, particularly in cirrhotics with low levels of plasma albumin. The curve of brain uptake of the tracer was modelled into a two compartments equation, which seems to provide a practical and reliable method to calculate the slopes of acquisition and decay, time to peak and maximal acquisition.

Avanços em psicofarmacologia - mecanismos de ação de psicofármacos hoje

Desde o início da história da psicofarmacologia moderna, na década de 40, vários avanços foram obtidos na elucidação do mecanismo de ação dos compostos psicoativos. O artigo aborda tais avanços enfocando as principais técnicas utilizadas, desde o desenvolvimento das técnicas de mensuração de aminas por emissão de fluorescência e da técnica de ligação fármaco-receptor, até a incorporação de técnicas sofisticadas, tais como as moleculares, para o estudo das alterações pós-receptor, o uso de marcadores genéticos e técnicas de imagem (PET, SPECT). Espera-se que tais progressos levem à elucidação dos mecanismos de ação dos psicofármacos, permitindo o desenvolvimento de novas moléculas terapêuticas específicas para regular as alterações subjacentes aos transtornos psiquiátricos.