An atlas of transcriptionally defined cell populations in the rat ventral tegmental area

Abstract

The ventral tegmental area (VTA) is a complex brain region that is essential for reward function but is also implicated in neuropsychiatric diseases including substance abuse. While decades of research on VTA function have focused on the role of dopaminergic neurons, recent evidence has identified critical roles for VTA GABAergic and glutamatergic neurons in reward processes as well. Interestingly, molecular characterization has revealed that subsets of these neurons express genes involved in the transport, synthesis, and vesicular packaging of multiple neurotransmitters, providing evidence for co-release neurons. However, these studies have largely relied on low-throughput methods, and the molecular architecture of the VTA has not been comprehensively examined. Here, we performed single nucleus RNA-sequencing (snRNA-seq) on 21,600 VTA cells from male and female Sprague-Dawley rats to generate a transcriptional atlas of the rat VTA. We identified 16 transcriptionally distinct cell types within the VTA, including 7 neuronal populations. Further subclustering revealed several VTA neuronal populations expressing markers for more than one neurotransmitter system, with one cluster exhibiting high expression levels of genes involved in the synthesis and transport of GABA, glutamate, and dopamine. Finally, snRNA-seq enabled the de novo identification of thousands of marker genes for each transcriptionally distinct population, revealing cluster-specific enrichment of gene sets implicated in neuropsychiatric and neurodevelopmental disorders, as well as specific phenotypes associated with alcohol and tobacco use. Together, these results highlight the heterogeneity of cellular populations in the VTA and identify novel markers and disease-linked genes enriched in distinct neuronal subtypes.

Transcriptomic diversity of cell types across the adult human brain

“…The EEL data additionally mirrored our RNA-seq analysis of splatter neurons more broadly. Although we did not dissect VTA for sequencing, rodent VTA neurons resemble splatter neurons in their combinatorial expression of neurotransmitters, neuropeptides, and their receptors ( 22 ). Indeed, GABAergic and glutamatergic neurons in the pons and VTA combinatorially co-expressed a number of neuropeptides (Fig 4.…”

Amphetamine disrupts dopamine axon growth in adolescence by a sex-specific mechanism

“…The guidance cue receptor DCC and its microRNA repressor miR-218 are highly enriched in dopamine neurons of the rodent ventral tegmental area (VTA; Fig 1a,b). 58,59 The expression of DCC protein and Dcc mRNA in the VTA decreases across postnatal development, 58,60,61 and can be altered by experience at discrete time points. Whether the effects of experience on Dcc expression are both age- and sex-specific remains to be explored.…”

“…(a) Dcc mRNA is expressed by 99% of dopamine neurons in the VTA. 59 (b) The microRNA miR-218 represses Dcc mRNA expression. 58,86 (c) Timeline of experiments in early adolescence.…”

Cocaine addiction-like behaviors are associated with long-term changes in gene regulation, energy metabolism, and GABAergic inhibition within the amygdala

“…Thus far, however, the application of single-cell assays to the study of addiction-like behaviors in rodents has been limited. Single nucleus RNA-seq (snRNA-seq) has been applied to characterize cellular diversity in brain regions involved in the reward system [32][33][34][35] , and has been used to analyze transcriptional changes induced by cocaine and morphine 36,37 . However, these prior studies used isogenic rodents, which means that genetically-mediated differences in susceptibility to addiction-like behaviors were not examined.…”