A New Dopamine Neuron Subtype for Morphine-Related Behavior
Cristina Rivera Quiles, Sarah C. Simmons, Olivia Dodson, Milagros Alday, Nicole Camacho Fontanez et al.
(see article e1662242025)
Ventral tegmental area (VTA) dopamine neurons regulate reward-related behavior and are hijacked by drugs of abuse, like opiates, to facilitate addiction. However, how opiates interact with distinct VTA dopamine neuron subpopulations is unclear. In this issue, Quiles et al. used mice to explore how the opiate morphine targets VTA dopamine neuron subpopulations. The researchers looked at gene expression changes in VTA dopamine neurons following long-term morphine exposure and discovered increased expression of the neuropeptide neuromedin S (NMS). Using a genetic mouse model enabling the targeting of NMS-expressing neurons, Quiles and colleagues found that artificially stimulating or inhibiting these neurons bidirectionally influenced locomotor activity associated with morphine use. Inhibiting NMS neurons also reduced morphine reward as measured by a conditioned place preference paradigm. The researchers used more experimental controls to highlight the morphine and NMS specificity of their findings. This identification of a new neuron subpopulation that morphine interacts with to affect behavior may inform treatment development for opiate addiction.
A subpopulation of NMS-expressing neurons (purple) was identified with a conditional viral vector in a special genetic line of mice (tyrosine hydroxylase, TH: green; mCherry: purple). See Quiles et al. for more information.
Parkinson's Disease Disrupts Premotor Cortex Activity
Claudia Marie Hendrix, Hannah E. Baker, Ying Yu, David D. Schneck, Jing Wang et al.
(see article e1802242025)
Research has overlooked the relationship between Parkinson's disease and pre-motor cortex dysfunction. To address this, Hendrix and colleagues explored how Parkinson's disease impacts activity in the presupplementary motor area (pre-SMA), which is involved in motor planning and control. While recording from the pre-SMA of two female non-human primates during a reaching task, the researchers discovered that reaction time during the task was positively associated with the activity of a subset of pre-SMA neurons prior to movement execution. However, when the nonhuman primates were in a Parkinson's disease state induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, pre-SMA activity prior to movement execution was disrupted and reaction time was slower. According to the authors, this work highlights the important role the pre-SMA may play in movement planning processes and suggests that poor movement planning in Parkinson's disease may be due to aberrant modulation of the pre-SMA.
Footnotes
This Week in The Journal was written by Paige McKeon
