Biology subjects

Lonjon, N.

Publications and source records attributed to Lonjon, N..

4 recordsLinked to original sources

bioRxiv2026

Oxytocin Modulation of Spinal Circuits Drives Therapeutic Benefits of Massage

Across social species, social touch enhances well-being and reduces pain -- two seemingly distinct benefits that enhance survival. Yet where and how the nervous system integrates these functions, and whether a single mechanism could serve both, remains unknown. Here we show that massage triggers oxytocin release, which shapes both pain and touch reward at the earliest stage of central processing -- the spinal cord -- through a single, state-dependent circuit mechanism. We report that in humans, massage enhances well-being, effects that correlate with endogenous oxytocin release. In mice, gentle touch activates hypothalamic oxytocin neurons that project directly to the spinal dorsal horn. Genetic manipulation of spinal oxytocin circuits alters behavioral responses to both gentle touch and noxious stimuli. Spinal calcium imaging and slice electrophysiology reveal that oxytocin acts on both excitatory and inhibitory spinal neurons to sculpt the relative activity of spinal ascending systems that convey both social touch and pain to the brain. Extending these findings to humans, we show that oxytocin receptors are also expressed on spinal excitatory and inhibitory neurons, and that endogenous oxytocin during massage correlates with altered spinal touch processing. Thus, spinal oxytocin signaling provides an evolutionarily conserved mechanism for the therapeutic benefits of massage.

neuroscience↗

bioRxiv2024

Functional expression and sex dimorphism of the T-type Cav3.2 Calcium Channel in human DRG Neurons

T-type/Cav3 calcium channels are key in neuronal excitability and pain processing with Cav3.2 being the prominent isoform in primary sensory neurons of the dorsal root ganglion (DRG). Its pharmacological inhibition or gene silencing induces analgesia in several preclinical models of inflammatory and neuropathic pain. However, the presence of Cav3.2, encoded by the CACNA1H gene, in human DRG neurons remains unresolved. Using RNA in-situ hybridization and electrophysiological recordings, we show that human DRGs express Cav3.2 in a subset of neurons positive for the neurotrophic factor receptor TrkB (NTRK2 gene). The Cav3.2 current exhibits typical biophysical and pharmacological properties, including inhibition by a low concentration of nickel and by Z944, a specific T-type calcium channel blocker in advanced clinical development. Conversely, ABT-639, a T-type calcium channel inhibitor that failed in Phase 2 trials for pain relief, does not inhibit Cav3.2 currents in human DRG neurons. Importantly, Cav3.2 currents are prominent in neurons from female organ donors, supporting the presence of sex differences in pain mechanisms in humans. These findings underscore the potential of continued exploration of Cav3.2 as a therapeutic target for pain treatment and highlight a specific subset of human neurons that likely rely on this channel to modulate their excitability.

neuroscience↗

bioRxiv2022

Persistence of FoxJ1+ Pax6+ Sox2+ ependymal cells throughout life in the human spinal cord

Spinal cord ependymal cells have stem cell properties in mice. They surround the central canal and keep expressing spinal cord developmental transcription factors. Similar cells exist in young humans however their persistence with aging is debated. We clarified this issue by collecting 17 spinal cords from organ donors, aged between 37 and 83 years old. We examined the presence of ependymal cells using immunohistochemistry on lightly-fixed tissue. We found the presence of cells expressing the typical ependymal marker FOXJ1 in the spinal cord central region in 100% of cases. In addition, a lumen surrounded by FOXJ1+ cells was observed in half of the cases. Like in mice, these human ependymal cells maintain the expression of SOX2 and PAX6 proteins together with RFX2 a master transcriptional regulator of ciliogenesis and ARL13B, a regulatory GTPase enriched in cilia. Reminiscent of the situation observed in mice and in young human spinal cord, a fetal-like regionalization of neurodevelopmental transcription factors was observed in three donors aged over 75 years: MSX1 and ARX/FOXA2 was preferentially expressed by dorsal and ventral ependymal cells, respectively. These results provide new evidence for the persistence of ependymal cells expressing neurodevelopmental genes throughout human life. The persistence of these cells in humans opens new opportunities to regenerate the spinal cord.

neuroscience↗

bioRxiv2022

The Human Motoneuron Expression Signature is Defined by ALS-Related Genes

The mammalian spinal cord functions as a community of glial and neuronal cell types to accomplish sensory processing, autonomic control, and movement; conversely, the dysfunction of these cell types following spinal cord injury or disease states can lead to chronic pain, paralysis, and death. While we have made great strides in understanding spinal cellular diversity in animal models, it is crucial to characterize human biology directly to uncover specialized features of basic function and to illuminate human pathology. Here, we present a cellular taxonomy of the adult human spinal cord using single nucleus RNA-sequencing with spatial transcriptomics and antibody validation. We observed 29 glial clusters, including rare cell types such as ependymal cells, and 35 neuronal clusters, which we found are organized principally by anatomical location. To demonstrate the potential of this resource for understanding human disease, we analyzed the transcriptome of spinal motoneurons that are prone to degeneration in amyotrophic lateral sclerosis (ALS) and other diseases. We found that, compared with all other spinal neurons, human motoneurons are defined by genes related to cell size, cytoskeletal structure, and ALS, thereby supporting a model of a specialized motoneuron molecular repertoire that underlies their selective vulnerability to disease. We include a publicly available browsable web resource with this work, in the hope that it will catalyze future discoveries about human spinal cord biology.

neuroscience↗