Alpha adrenoceptors modulate VTA and PFC in cocaine sensitization

α 肾上腺素受体调节可卡因致敏中的 VTA 和 PFC

• 批准号: 7679417
• 负责人: CARLOS A JIMENEZ-RIVERA
• 金额: $ 26.25万
• 依托单位: UNIVERSITY OF PUERTO RICO MED SCIENCES
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-09-01 至 2012-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7679417
• 关键词: Adrenergic Receptor; Affinity; Agonist; Animals; Area; Autoradiography; Behavioral Model; Binding; Biological Assay; Cells; Cocaine; Cocaine Dependence; Development; Dopamine; Drug Addiction; Drug effect disorder; Funding; GTP-Binding Proteins; Glutamates; Goals; In Vitro; Intervention; Journals; Knowledge; Laboratories; Mediating; Microinjections; Modeling; Motor; Neuraxis; Neurons; Neurosciences; Paper; Peer Review; Pharmaceutical Preparations; Physiologic pulse; Play; Prefrontal Cortex; Presynaptic Terminals; Process; Productivity; Protocols documentation; Publications; Rattus; Receptors, Adrenergic, alpha-2; Research; Research Personnel; Research Proposals; Role; Staging; Structure; System; Techniques; Testing; Therapeutic; Ventral Tegmental Area; Withdrawal; Work; alpha-adrenergic receptor; base; behavioral sensitization; blind; cocaine exposure; design; meetings; neuroadaptation; noradrenergic; patch clamp; postsynaptic; presynaptic; protein activation; receptor; receptor coupling

DESCRIPTION (provided by applicant): Cocaine sensitization is a progressive and long-lasting enhancement of the motor stimulant effect induced by a subsequent cocaine challenge. The goal of this work is to elucidate the role of alpha adrenergic receptors at the VTA and RFC in the development and expression of cocaine sensitization. There are three specific Aims: 1) Assess whether microinjections of alpha noradrenergic receptor agonists and antagonists into the VTA or RFC modulate the process of cocaine sensitization. Using the model of cocaine sensitization, intra-VTA or -RFC microinjections of selective alpha-noradrenergic receptor agonists and antagonists will be used to localize the anatomical structure mediating the pharmacological actions of these drugs. 2) Identify changes in alpha noradrenergic receptors at the VTA and RFC induced by behavioral sensitization. We will investigate alpha-1 and alpha-2 adrenergic receptor mediated G protein activation in cocaine-sensitized rats using agonist-stimulated [35S] GTPyS binding as a functional assay. The hypothesis is that development of cocaine sensitization involves an increase in alpha-1 and a decrease in alpha-2 receptor functional sensitivity in both VTA and RFC areas, which will promote cocaine sensitization. Correlations will be made between changes in functionality and number/affinities of receptors in each structure using an in vitro receptor autoradiography assay. We will also assess whether changes in these noradrenergic receptors play a role in the initiation or expression of behavioral sensitization by comparing animals after a 7days withdrawal period. 3) Determine the role of alpha-2 receptors in the modulation of glutamate release at .the VTA. In vitro whole cell patch clamp recordings will be employed to study the role of alpha-2 receptors in the modulation of glutamate release onto VTA dopamine cells. The effects of alpha-2 adrenoreceptor agonists on glutamate-induced excitatory postsynaptic currents (EPSCs) will be assessed. Paired-pulse ratios and miniature EPSCs will be employed to provide evidence that the EPSC's alterations are localized at the presynaptic terminal. The hypothesis is that presynaptic alpha-2 receptors control glutamate release onto VTA neurons. A sub-hypothesis is that there is a decreased alpha-2 -induced inhibition of glutamate release in cocaine sensitized rats. Changes in alpha adrenoceptor modulation of glutamate release into VTA cells after a withdrawal period will also be determined. Understanding of alpha adrenoceptor modulatory changes in cocaine sensitization will increase our knowledge of the role of the noradrenergic system in cocaine addiction and might provide possible avenues for therapeutic pharmacological interventions..

描述（由申请人提供）：可卡因敏化是随后的可卡因挑战引起的运动刺激效应的进行性和持久的增强。这项工作的目的是阐明α肾上腺素能受体在VTA和RFC在可卡因敏化的发展和表达中的作用。有三个特定的目的：1）评估α甲肾上腺素能受体激动剂和拮抗剂的显微注射是否在VTA或RFC中调节可卡因敏化过程。使用可卡因敏化模型，选择性α-甲状腺素能受体激动剂和拮抗剂的VTA内或-RFC显微注射将用于定位介导这些药物的药理作用的解剖结构。 2）确定行为敏化引起的VTA和RFC处α去肾上腺素能受体的变化。我们将使用Agonist刺激的[35S] GTPYS结合作为功能分析的Agonist刺激[35S] GTPYS，研究可卡因敏化大鼠中α-1和α-2肾上腺素能受体介导的G蛋白激活。假设是，可卡因敏化的发展涉及α-1的增加，而VTA和RFC地区的α-2受体功能敏感性降低，这将促进可卡因敏化。使用体外受体放射自显影测定法，将在每个结构中的功能变化与受体数量/亲和力之间建立相关性。我们还将评估这些去甲肾上腺素能受体的变化是否在7天戒断期后通过比较动物来在行为敏化的开始或表达中起作用。 3）确定α-2受体在VTA的调节中的作用。将采用体外全细胞贴片夹记录来研究α-2受体在谷氨酸释放到VTA多巴胺细胞中的调节中的作用。将评估α-2肾上腺素受体激动剂对谷氨酸引起的兴奋性突触后电流（EPSC）的影响。配对脉冲比率和微型EPSC将用于提供证据，表明EPSC的变化位于突触前末端。假设是突触前α-2受体控制谷氨酸释放到VTA神经元上。亚蛋白结构是在可卡因敏化大鼠中降低了α-2诱导的谷氨酸释放的抑制作用。戒断期后，谷氨酸释放到VTA细胞中的α肾上腺素受体调节的变化也将得到确定。 了解可卡因敏感性的α肾上腺素受体调节变化将增加我们对去甲肾上腺素能系统在可卡因成瘾中的作用的了解，并可能为治疗性药理干预提供可能的途径。