Large scale human genome wide association studies (GWAS) have identified a growing pool of genes associated with cigarette smoking. One of the most prominent, phosphodiesterase-4B (PDE4B), has been associated with multiple smoking phenotypes. Although PDE4B modulates the half-life of neuronal cAMP, its precise role in smoking behaviors is unknown. To address this knowledge gap, we used a reverse translational approach. We inactivated PDE4B in bilateral medial nucleus accumbens shell (NAcs) neurons by injecting AAV containing a specific gRNA in female transgenic Cas9+ Long Evans rats. These rats then were given 23-h chronic access to nicotine intravenous self-administration (IVSA) under a schedule of increasing fixed ratios (FR). With the increased effort required at FR7, nicotine SA (i.e. active presses and drug infusions) declined significantly in controls, whereas it was maintained in the mutagenized group. A progressive ratio (PR) study also showed significantly greater cumulative nicotine infusions in the PDE4B-edited group. Hence, we hypothesized that enhanced PDE4B protein activity would reduce nicotine IVSA. A positive allosteric modulator, 2-(3-(4-chloro-3-fluorophenyl)-5-ethyl-1H-1,2,4-triazol-1-yl)-N-(3,5-dichlorobenzyl)acetamide (MR-L2), was microinfused into NAcs bilaterally at FR3 or FR5; in both cohorts, MR-L2 acutely reduced nicotine IVSA. In summary, these studies show that the activity of PDE4B regulates the capacity of NAcs to maintain nicotine IVSA in face of the cost of increasing work. This finding and the results of the PR study indicate that PDE4B affects the motivation to obtain nicotine. These reverse translational studies in rats provide insight into the motivational effects of NAcs PDE4B that advance our understanding of the smoking behaviors mapped in human GWAS.

大规模人类全基因组关联研究（GWAS）已经确定了越来越多与吸烟相关的基因。其中最突出的一种是磷酸二酯酶 4B (PDE4B)，它与多种吸烟表型相关。尽管 PDE4B 调节神经元 cAMP 的半衰期，但其在吸烟行为中的确切作用尚不清楚。为了解决这一知识差距，我们使用了逆翻译方法。我们通过向雌性转基因 Cas9+ Long Evans 大鼠注射含有特定 gRNA 的 AAV 来灭活双侧内侧伏隔核壳 (NAcs) 神经元中的PDE4B 。然后，按照增加固定比率 (FR) 的时间表，对这些大鼠进行 23 小时长期尼古丁静脉内自我给药 (IVSA)。随着 FR7 所需努力的增加，尼古丁 SA（即主动按压和药物输注）在对照组中显着下降，而在诱变组中则保持不变。渐进比率 (PR) 研究还显示，PDE4B编辑组的累积尼古丁输注量显着增加。因此，我们假设增强 PDE4B 蛋白活性会减少尼古丁 IVSA。一种正变构调节剂，2-(3-(4-氯-3-氟苯基)-5-乙基-1H-1,2,4-三唑-1-基)-N-(3,5-二氯苄基)乙酰胺( MR-L2)，在 FR3 或 FR5 处微量输注至双侧 NAc；在这两个队列中，MR-L2 均显着降低了尼古丁 IVSA。总之，这些研究表明，面对增加的工作成本，PDE4B 的活性调节 NAcs 维持尼古丁 IVSA 的能力。这一发现和 PR 研究的结果表明，PDE4B 影响获取尼古丁的动机。 这些在大鼠中进行的反向转化研究深入了解了 NAcs PDE4B 的激励作用，从而增进了我们对人类 GWAS 中吸烟行为的理解。