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Antipsychotic Drug Vesicular Release at Dopamine Synapses

多巴胺突触的抗精神病药物囊泡释放

基本信息

批准号：
9125571
负责人：
EDWIN S LEVITAN
金额：
$ 22.65万
依托单位：
UNIVERSITY OF PITTSBURGH AT PITTSBURGH
依托单位国家：
美国
项目类别：
财政年份：
2016
资助国家：
美国
起止时间：
2016-05-15 至 2018-02-28
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9125571
关键词：
Action Potentials Acute Address Affect Agonist Amines Amphetamines Animals Antidepressive Agents Antipsychotic Agents Attenuated Autoreceptors Bathing Behavior Biological Assay Blood - brain barrier anatomy Brain Cell Culture Techniques Charge Corpus striatum structure Dopamine Dopamine D2 Receptor Dopamine Receptor Dorsal Dose Drug Design Drug effect disorder Dyes Electrodes Employee Strikes Exocytosis Frequencies Hippocampus (Brain)Hour Image In Vitro Kinetics Lead Life LysoTracker Measures Mediating Membrane Mental Depression Microscopy Midbrain structure Mus Neurons Organelles Pattern Pharmaceutical Preparations Physiological Predisposition Proteins Protocols documentation Quinpirole Rattus Slice Substantia nigra structure Synapses Synaptic Cleft Synaptic Vesicles Testing Therapeutic Time Uncertainty Vesicle Wit Work base carbon fiber design dopamine transporter dopaminergic neuron in vivo monoamine nanomolar neurotransmission novel therapeutics patch clamp postsynaptic protonation public health relevance receptor function research study response transmission process two-photon uptake vesicular monoamine transporter vesicular release

项目摘要

DESCRIPTION (provided by applicant): Antipsychotic drugs are D2 dopamine receptor competitive antagonists. It has long been speculated that these drugs, which are weak base amines that cross the blood brain barrier, accumulate by acidic trapping in acidic organelles including synaptic vesicles. Previous experiments addressing this hypothesis relied on acidophilic dyes that are not psychiatric drugs and cell cultures that do not recapitulate D2 receptor-dependent neurotransmission. Therefore, we identified a clinically used antipsychotic drug that can be directly imaged in the brain slice by two-photon microscopy. Our experiments established that this antipsychotic is subject to acidic trapping, including in midbrain dopamine neuron synaptic vesicles, which contain the native transmitter. Furthermore, we showed that the antipsychotic drug can be released from vesicles by action potentials, which requires Ca2+, or an amphetamine, which requires the dopamine transporter and the vesicular monoamine transporter. Vesicular accumulation and release were seen at a therapeutic concentration in vitro and with systemic administration in animals. Thus, these results demonstrated for the first time that an antipsychotic drug is subject to vesicular release with dopamine at synapses. This finding is intriguing because it implies that local antipsychotic drug concentration will scale wit dopamine exactly where and when dopamine synapses are active. Given that synaptic vesicular release of an antipsychotic drug has now been established, this proposal determines the functional impact of vesicular antipsychotic drug release on dopaminergic transmission mediated by D2 receptors in the substantia nigra and the striatum. Our working hypothesis is that efficacy of the vesicular drug will increase with repetitive firing, which is relevant for behavior. As acidic trapping is passive and cannot be disrupted without inhibiting vesicular storage of dopamine, experiments make use of the striking difference in kinetics of vesicular trapping (i.e., it occurs over hours and then is long lasting) and acute application of the drug vi the bath (i.e., in minutes) that was revealed by two-photon microscopy. Striatum experiments are focused on electrochemically measured dopamine overflow, which is subject to frequency dependent inhibition by D2 autoreceptors. Substantia nigra experiments utilize patch clamping of dopamine neurons to assay spontaneous miniature and evoked inhibitory currents that are induced by somatodendritic D2 receptors. Together, these complementary approaches will ascertain the impact of activity-dependent vesicular release of antipsychotic drug on synaptic D2 receptor function.