Molecular interrogation of hypothalamic organization reveals distinct dopamine neuronal subtypes

Abstract

The hypothalamus contains the highest diversity of neurons in the brain. Many of these neurons can co-release neurotransmitters and neuropeptides in a use-dependent manner. Investigators have hitherto relied on candidate protein-based tools to correlate behavioral, endocrine and gender traits with hypothalamic neuron identity. Here we map neuronal identities in the hypothalamus by single-cell RNA sequencing. We distinguished 62 neuronal subtypes producing glutamatergic, dopaminergic or GABAergic markers for synaptic neurotransmission and harboring the ability to engage in task-dependent neurotransmitter switching. We identified dopamine neurons that uniquely coexpress the Onecut3 and Nmur2 genes, and placed these in the periventricular nucleus with many synaptic afferents arising from neuromedin S neurons of the suprachiasmatic nucleus. These neuroendocrine dopamine cells may contribute to the dopaminergic inhibition of prolactin secretion diurnally, as their neuromedin S inputs originate from neurons expressing Per2 and Per3 and their tyrosine hydroxylase phosphorylation is regulated in a circadian fashion. Overall, our catalog of neuronal subclasses provides new understanding of hypothalamic organization and function.

Hypothalamic CNTF volume transmission shapes cortical noradrenergic excitability upon acute stress

“…Recently, we have demonstrated that both glutamatergic and GABAergic subtypes of CRH + neurons exist in the mammalian hypothalamus (Romanov et al , 2015, 2017b). We have recently tied CRH + neuroendocrine cells to the HPA axis as its first‐responder “ stress‐on ” components by identifying their use of Scgn , a parvocellular neuron‐specific Ca 2+ ‐sensor protein, to facilitate fast vesicular neuropeptide secretion (Romanov et al , 2015, 2017a).…”

“…Crh‐Ires ‐Cre (from J.S. Bains, University of Calgary, Canada) were crossed with B6.Cg‐ Gt(ROSA)26Sor tm6(CAG‐ZsGreen1)Hze /J mice ( Ai6 ; JAX stock #012704 and #007906) to visualize periventricular innervation by CRH neurons (Romanov et al , 2017a,b). Scgn ‐Cre mice were developed using the BAC technology (Calvigioni et al , 2017; Z.M., F.E., and G.S., Institute of Experimental Medicine, Hungarian Academy of Sciences).…”

“…Stereotaxic injections were performed as described (Romanov et al , 2017a,b). Briefly, mice were anesthetized with isoflurane (5%, 1 l/min flow rate) and placed in a stereotaxic frame (Narishige).…”

“…C57Bl6/N juvenile mice (P14–28) of both sexes in control were used for single‐cell collection as described (Romanov et al , 2017a,b). The processing of cells from male and female animals was random to minimize methodological bias.…”

“…Ependymal cells were classified by Enkur and Foxj1 expression (Romanov et al , 2017b), and also contained Cntf mRNAs. (C1) Reconstruction of GRIA1 + ependymal cells receiving VGLUT2 + synapses ( arrowheads ).…”