Slaker Megan, Barnes Jesse, Sorg Barbara A, Grimm Jeffrey W
Department of Integrative Physiology and Neuroscience and Translational Addiction Research Center, Washington State University, Vancouver, Washington, United States of America.
Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, Washington, United States of America.
PLoS One. 2016 Dec 15;11(12):e0168256. doi: 10.1371/journal.pone.0168256. eCollection 2016.
Perineuronal nets (PNNs) are aggregates of extracellular matrix that form structures surrounding a subset of GABAergic interneurons. The staining intensity of PNNs appears to be related to plasticity. Environmental enrichment (EE) influences plasticity during adulthood: EE decreases the rewarding effects of drugs of abuse and diminishes both drug- and sucrose-seeking behavior. We determined the impact of EE on PNN intensity in the medial prefrontal cortex (mPFC) in rats trained to self-administer sucrose. We examined the number and intensity of PNNs within the prelimbic (PL), infralimbic (IL), and orbitofrontal (OF) regions of the mPFC of adult Long-Evans rats that were trained for sucrose self-administration followed by acute or chronic EE during abstinence and a cue-induced reinstatement test. Rats exposed to EE prior to a cue-induced reinstatement of sucrose seeking had an increase in PNN staining compared with rats in standard housing. Conversely, naïve rats given 1 day of EE had a decrease in PNN intensity in the PL, no change in the IL, and an increase in the OF. Our findings demonstrate that EE increases PNN intensity in the mPFC after sucrose training, suggesting that training enhances the ability of EE to increase PNN intensity. We further demonstrate an interaction between time of abstinence, duration of EE exposure, and cue-induced reinstatement. Our results suggest that increased PNN intensity after EE may alter the excitatory/inhibitory balance of mPFC neurons such that rats are less responsive to a sucrose cue.
神经周网（PNNs）是细胞外基质的聚集体，形成围绕一部分γ-氨基丁酸能中间神经元的结构。PNNs的染色强度似乎与可塑性有关。环境富集（EE）会影响成年期的可塑性：EE会降低滥用药物的奖赏效应，并减少对药物和蔗糖的觅求行为。我们确定了EE对经训练自我给药蔗糖的大鼠内侧前额叶皮质（mPFC）中PNN强度的影响。我们检查了成年Long-Evans大鼠mPFC的前边缘区（PL）、下边缘区（IL）和眶额区（OF）内PNNs的数量和强度，这些大鼠先接受蔗糖自我给药训练，然后在禁欲期间进行急性或慢性EE处理，并进行线索诱导的复吸试验。与饲养在标准环境中的大鼠相比，在线索诱导的蔗糖觅求复吸前暴露于EE的大鼠PNN染色增加。相反，仅接受1天EE处理的未训练大鼠，其PL区的PNN强度降低，IL区无变化，OF区增加。我们的研究结果表明，蔗糖训练后EE会增加mPFC中的PNN强度，这表明训练增强了EE增加PNN强度的能力。我们进一步证明了禁欲时间、EE暴露持续时间和线索诱导的复吸之间的相互作用。我们的结果表明，EE后PNN强度增加可能会改变mPFC神经元的兴奋/抑制平衡，从而使大鼠对蔗糖线索的反应性降低。
