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: 7917224
• 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/7917224
• 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）：可卡因致敏是由随后的可卡因激发引起的运动兴奋作用的渐进且持久的增强。这项工作的目标是阐明 VTA 和 RFC 的 α 肾上腺素受体在可卡因致敏的发展和表达中的作用。有三个具体目标： 1) 评估将 α 去甲肾上腺素受体激动剂和拮抗剂显微注射到 VTA 或 RFC 中是否调节可卡因致敏过程。使用可卡因致敏模型，选择性 α-去甲肾上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药理作用的解剖结构。 2) 识别行为敏化引起的 VTA 和 RFC α 去甲肾上腺素能受体的变化。我们将使用激动剂刺激的 [35S] GTPyS 结合作为功能测定，研究可卡因致敏大鼠中 α-1 和 α-2 肾上腺素受体介导的 G 蛋白激活。假设可卡因致敏的发生涉及 VTA 和 RFC 区域中 α-1 的增加和 α-2 受体功能敏感性的降低，这将促进可卡因致敏。将使用体外受体放射自显影测定在每个结构中受体的功能性和数量/亲和力的变化之间建立关联。我们还将通过比较 7 天停药期后的动物来评估这些去甲肾上腺素能受体的变化是否在行为敏化的启动或表达中发挥作用。 3) 确定 α-2 受体在调节 VTA 谷氨酸释放中的作用。体外全细胞膜片钳记录将用于研究α-2受体在调节VTA多巴胺细胞上谷氨酸释放中的作用。将评估 α2 肾上腺素受体激动剂对谷氨酸诱导的兴奋性突触后电流 (EPSC) 的影响。成对脉冲比和微型 EPSC 将用于提供 EPSC 的改变位于突触前末端的证据。假设是突触前 α-2 受体控制谷氨酸释放到 VTA 神经元上。一个子假设是，在可卡因致敏的大鼠中，α-2 诱导的谷氨酸释放抑制作用减弱。停药期后，α 肾上腺素受体调节谷氨酸释放到 VTA 细胞中的变化也将被确定。 了解可卡因致敏中的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，并可能为治疗药物干预提供可能的途径。