Cuesta Santiago, Restrepo-Lozano José Maria, Popescu Christina, He Susan, Reynolds Lauren M, Israel Sonia, Hernandez Giovanni, Rais Rana, Slusher Barbara S, Flores Cecilia
Department of Psychiatry and Department of Neurology and Neurosurgery, McGill University, Douglas Mental Health University Institute, Montreal, Quebec, Canada.
Integrated Program in Neuroscience, McGill University, Montreal, Quebec, Canada.
Addict Biol. 2020 Jul;25(4):e12791. doi: 10.1111/adb.12791. Epub 2019 Jun 13.
The guidance cue receptor DCC controls mesocortical dopamine development in adolescence. Repeated exposure to an amphetamine regimen of 4 mg/kg during early adolescence induces, in male mice, downregulation of DCC expression in dopamine neurons by recruiting the Dcc microRNA repressor, microRNA-218 (miR-218). This adolescent amphetamine regimen also disrupts mesocortical dopamine connectivity and behavioral control in adulthood. Whether low doses of amphetamine in adolescence induce similar molecular and developmental effects needs to be established. Here, we quantified plasma amphetamine concentrations in early adolescent mice following a 4 or 0.5 mg/kg dose and found peak levels corresponding to those seen in humans following recreational and therapeutic settings, respectively. In contrast to the high doses, the low amphetamine regimen does not alter Dcc mRNA or miR-218 expression; instead, it upregulates DCC protein levels. Furthermore, high, but not low, drug doses downregulate the expression of the DCC receptor ligand, Netrin-1, in the nucleus accumbens and prefrontal cortex. Exposure to the low-dose regimen did not alter the expanse of mesocortical dopamine axons or their number/density of presynaptic sites in adulthood. Strikingly, adolescent exposure to the low-dose drug regimen does not impair behavioral inhibition in adulthood; instead, it induces an overall increase in performance in a go/no-go task. These results show that developmental consequences of exposure to therapeutic- versus abused-like doses of amphetamine in adolescence have dissimilar molecular signatures and opposite behavioral effects. These findings have important clinical relevance since amphetamines are widely used for therapeutic purposes in youth.
导向线索受体DCC控制青春期的中脑皮质多巴胺发育。在青春期早期,雄性小鼠反复暴露于4mg/kg的苯丙胺方案下,通过招募Dcc微小RNA抑制因子微小RNA-218(miR-218),诱导多巴胺神经元中DCC表达下调。这种青春期苯丙胺方案还会破坏成年期的中脑皮质多巴胺连接性和行为控制。青春期低剂量苯丙胺是否会诱导类似的分子和发育效应尚待确定。在此,我们对青春期早期小鼠在4mg/kg或0.5mg/kg剂量后血浆苯丙胺浓度进行了定量,发现峰值水平分别对应于娱乐和治疗环境下人类的水平。与高剂量不同,低剂量苯丙胺方案不会改变Dcc mRNA或miR-218的表达;相反,它会上调DCC蛋白水平。此外,高剂量而非低剂量药物会下调伏隔核和前额叶皮质中DCC受体配体Netrin-1的表达。成年期暴露于低剂量方案不会改变中脑皮质多巴胺轴突的范围或其突触前位点的数量/密度。引人注目的是,青春期暴露于低剂量药物方案不会损害成年期的行为抑制;相反,它会在“去/不去”任务中诱导整体表现的提高。这些结果表明,青春期暴露于治疗剂量与滥用剂量的苯丙胺所产生的发育后果具有不同的分子特征和相反的行为效应。这些发现具有重要的临床意义,因为苯丙胺在青少年中广泛用于治疗目的。