Transcriptional subtypes, anatomical organization, and sexual dimorphism of sensory vagus neurons in Danionella cerebrum
Visceral sensory neurons sense and modulate the brain, behavior, and the internal organs. However, these neurons have been difficult to study comprehensively due to their projections deep within the body. Here, we establish the transparent miniature fish Danionella cerebrum as a model for studying the sensory vagus nerve in an adult vertebrate. By generating a transgenic line to label D. cerebrum…
The transparent miniature fish Danionella cerebrum has been identified as a valuable model for studying the sensory vagus nerve in an adult vertebrate. Researchers have established a transgenic line to label the cranial sensory ganglia, allowing them to both anatomically characterize and transcriptionally profile the sensory vagus at single-cell resolution.
Anatomically, the vagal ganglia of D. cerebrum exhibit a somatotopic layout. This means that different parts of the ganglia are associated with different types of sensory input. Transcriptionally, the sensory vagus is composed of diverse sensory subtypes that are conserved across other vertebrates. These subtypes include nutrient-sensing, mechanoreceptive, nociceptive, and thermosensitive subtypes, as well as polymodal combinations that involve multiple sensory modalities.
Visualizing the marker genes for these sensory subtypes revealed that the sensory vagus is organized somatotopically, with different subtypes residing in specific regions of the ganglia. This somatotopic organization suggests that the sensory input processed by the sensory vagus is organized in a spatial manner, with different parts of the ganglia responding to different types of sensory information.
One of the most notable findings of this study is the dynamic nature of the D. cerebrum sensory vagus during development. As the fish matures sexually, the vagal ganglia become anatomically sexually dimorphic, meaning that there are differences in structure and organization between males and females. Additionally, the sensory vagus undergoes continuous adult neurogenesis, a process in which new neurons are generated throughout adulthood.
The molecular and anatomical atlas of the sensory vagus provided by this study lays the groundwork for future functional studies of body-brain communication in D. cerebrum. By understanding the organization and diversity of the sensory vagus, researchers can begin to explore how sensory input from the body is processed and integrated with brain function in this model organism.
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