The paradoxical effects of reward and aversion with abused drugs may interact to produce drug addiction, which is the so-called paradoxical effect hypothesis of abused drugs. However, there is no research examining how the ventral tegmental area (VTA) or periaqueductal gray matter (PAG) regulates morphine's paradoxical effect of reward and aversion. The present study addresses this issue, utilizing a high concentration of N-methyl-D-aspartic acid (NMDA) via injections to destroy the VTA or the PAG. Moreover, the study employed the new "pre- and postassociation" experimental paradigm (2010) to test whether the simultaneous rewarding and aversive effects of morphine can be affected by an NMDA lesion in the VTA or the PAG. The results indicated that the NMDA lesion of the VTA simultaneously reduced morphine-induced conditioned suppression of saccharin solution intake in conditioned taste aversion (CTA) and morphine-induced spent time in the preference compartment in conditioned place preference (CPP), whereas the PAG lesion did not change either measure. Thus, the VTA, but not the PAG, appears to contribute to the paradoxical effect reward in CPP and aversion in CTA induced by morphine. The VTA's involvement in morphine-induced CTA aversion and CPP reward supports the paradoxical effect hypothesis of abused drugs. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

中文翻译：

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腹侧被盖区但不是导水管周围灰质参与吗啡的矛盾奖励和厌恶作用。

奖赏和厌恶与滥用药物的悖论效应可能相互作用产生毒瘾，这就是所谓的滥用药物的悖论效应假说。然而，没有研究检查腹侧被盖区 (VTA) 或导水管周围灰质 (PAG) 如何调节吗啡的奖赏和厌恶的矛盾效应。本研究解决了这个问题，通过注射使用高浓度的 N-甲基-D-天冬氨酸 (NMDA) 来破坏 VTA 或 PAG。此外，该研究采用了新的“关联前和关联后”实验范式（2010）来测试吗啡的同时奖励和厌恶效应是否会受到 VTA 或 PAG 中的 NMDA 病变的影响。结果表明，VTA 的 NMDA 损伤同时减少了条件性味觉厌恶 (CTA) 中吗啡诱导的糖精溶液摄入的条件抑制和吗啡诱导的条件性位置偏好 (CPP) 中的偏好隔室中的花费时间，而 PAG 损伤没有改变任何一项措施。因此，VTA，而不是 PAG，似乎有助于 CPP 中的矛盾效应奖励和吗啡诱导的 CTA 厌恶。VTA 参与吗啡诱导的 CTA 厌恶和 CPP 奖励支持滥用药物的矛盾效应假设。（PsycInfo 数据库记录 (c) 2021 APA，保留所有权利）。而 PAG 病变没有改变任何一项措施。因此，VTA，而不是 PAG，似乎有助于 CPP 中的矛盾效应奖励和吗啡诱导的 CTA 厌恶。VTA 参与吗啡诱导的 CTA 厌恶和 CPP 奖励支持滥用药物的矛盾效应假设。（PsycInfo 数据库记录 (c) 2021 APA，保留所有权利）。而 PAG 病变没有改变任何一项措施。因此，VTA，而不是 PAG，似乎有助于 CPP 中的矛盾效应奖励和吗啡诱导的 CTA 厌恶。VTA 参与吗啡诱导的 CTA 厌恶和 CPP 奖励支持滥用药物的矛盾效应假设。（PsycInfo 数据库记录 (c) 2021 APA，保留所有权利）。