NeuN+ neuronal nuclei in non-human primate prefrontal cortex and subcortical white matter after clozapine exposure

Abstract

Increased neuronal densities in subcortical white matter have been reported for some cases with schizophrenia. The underlying cellular and molecular mechanisms remain unresolved. We exposed 26 young adult macaque monkeys for 6 months to either clozapine, haloperidol or placebo and measured by structural MRI frontal gray and white matter volumes before and after treatment, followed by observer-independent, flow-cytometry-based quantification of neuronal and non-neuronal nuclei and molecular fingerprinting of cell-type specific transcripts. After clozapine exposure, the proportion of nuclei expressing the neuronal marker NeuN increased by approximately 50% in subcortical white matter, in conjunction with a more subtle and non-significant increase in overlying gray matter. Numbers and proportions of nuclei expressing the oligodendrocyte lineage marker, OLIG2, and cell-type specific RNA expression patterns, were maintained after antipsychotic drug exposure. Frontal lobe gray and white matter volumes remained indistinguishable between antipsychotic-drug-exposed and control groups. Chronic clozapine exposure increases the proportion of NeuN+ nuclei in frontal subcortical white matter, without alterations in frontal lobe volumes or cell type-specific gene expression. Further exploration of neurochemical plasticity in non-human primate brain exposed to antipsychotic drugs is warranted.

Neuronal and glial 3D chromatin architecture illustrates cellular etiology of brain disorders

“…We found that NeuN− cells showed higher structural similarity with the adult brain than the fetal brain, indicative of gliogenesis in the postnatal brain 24 . Intriguingly, NeuN− cells did not show high structural similarity with iPSC-derived astrocytes, consistent with the previous report that the majority of NeuN− cells are oligodendrocytes 25 . NeuN+ cells showed high similarity with adult brains, fetal brains, and iPSC-derived neurons.…”

“…As expected, NeuN+ and NeuN− FIREassociated genes were mainly enriched in neurons and glia, respectively (Figure 1i-j). In particular, NeuN− FIRE-associated genes were most highly expressed in oligodendrocytes, confirming that NeuN− cells are enriched for oligodendrocytes 25 .…”

Cell type-specific isolation and transcriptomic profiling informs glial pathology in human temporal lobe epilepsy

“…Nuclei isolation from snap-frozen tissue circumvents the problem of cytoplasmic cell-cell processes dissociation and minimizes transcriptome alterations or artifacts that may be incurred during purification or cell culture 58 . Previous attempts to characterize glia using this method have been largely limited to the analysis of NEUN-("non-neuronal") populations, which are fundamentally heterogeneous and include endothelium, pericytes, smooth muscles, microglia and other inflammatory cells, in addition to astrocyte and oligodendroglial lineages 25,[59][60][61] . Few studies have used OLIG2 or SOX10 to isolate oligodendroglial populations from the NEUN-fraction 62 (unpublished), and a single study has demonstrated the use of SOX9 to sort astrocyte nuclei from mouse brain 27 .…”

Acute and chronic effects of clozapine on cholinergic transmission in cultured mouse superior cervical ganglion neurons

“…Clozapine treatment in culture increases the density of dendritic spine and up-regulates the number of postsynaptic densities at glutamatergic synapses (Critchlow et al, 2006). In primates, after chronic clozapine exposure, the proportion of nuclei expressing the neuronal marker NeuN increased significantly in subcortical white matter (Halene et al, 2016). Our data show that therapeutic concentrations of clozapine do not affect the neuronal survival rate; however, we cannot exclude potential presynaptic and postsynaptic ultrastructural changes at the nicotinic synapse.…”