The Role of the Peripheral Sensory Nervous System in Regulation

Functions of the Peripheral Sensory Nervous System

The PNS consists of two primary subdivisions: the somatosensory nervous system and the visceral sensory system. The somatosensory nervous system is responsible for detecting and responding to external stimuli such as touch, temperature, and pain, while the visceral sensory system monitors internal physiological states, including organ function and blood pressure (Mei et al., 2025).

1. Somatosensory Nervous System

The somatosensory system mediates the transmission and integration of sensory modalities, including tactile perception, nociception, and proprioception. Somatosensory neurons, primarily located in dorsal root ganglia (DRG), exhibit pseudounipolar morphology and transmit signals through bifurcated axons. This unique structure allows them to relay sensory information to central synaptic targets while simultaneously innervating peripheral sensory receptors (Mei et al., 2025).

The classification of somatosensory nerve fibers includes:

• C fibers: Unmyelinated fibers responsible for slow, dull pain sensations and temperature detection.
• Aδ fibers: Myelinated fibers that transmit sharp, acute pain and rapid temperature changes.
• Aβ fibers: Myelinated fibers that primarily mediate tactile sensations.

Recent research has identified specific molecular markers and activation characteristics of sensory neuron subtypes, particularly nociceptors, which are crucial for transmitting both acute and chronic pain signals (Mei et al., 2025).

2. Visceral Sensory System

The visceral sensory system functions to monitor the internal environment and maintain physiological homeostasis. Visceral sensory neurons are located in various ganglia, including the DRG and vagal ganglia (VG). These neurons play crucial roles in regulating autonomic responses to internal stimuli, such as visceral distension and chemical changes in the gastrointestinal tract (Mei et al., 2025).

Visceral sensory neurons are characterized by their ability to detect and respond to mechanical, chemical, and thermal changes. They also play significant roles in modulating reflex responses, including those related to digestion and cardiovascular regulation (Mei et al., 2025).

Mechanisms of Neuro-Immune Interactions in Health

Emerging evidence suggests that the PNS plays a critical role in regulating immune responses. Sensory neurons, particularly nociceptors, not only detect harmful stimuli but also actively participate in the immune response by releasing neuropeptides that modulate the activity of immune cells. These interactions form neuro-immune cell units (NICUs), which are specialized structures where neurons and immune cells communicate and regulate local immune activity (Mei et al., 2025).

For example, calcitonin gene-related peptide (CGRP), released by sensory neurons, can enhance the production of antibodies by B cells in the spleen, while also promoting the recruitment and activation of immune cells in the context of tissue injury (Mei et al., 2025). This highlights the dual role of sensory neurons in both sensing danger signals and modulating immune responses to maintain tissue homeostasis.

Contributions of Sensory Neurons to Organ Homeostasis

Sensory neurons play an essential role in regulating the functions of various organs. For instance, in the gastrointestinal tract, sensory neurons detect distension and release neuropeptides that regulate gastrointestinal motility and stimulate the secretion of digestive enzymes (Mei et al., 2025). In the lungs, vagal sensory neurons modulate airway tone and respiratory responses to inhaled irritants, while also influencing the local immune response to pathogens (Mei et al., 2025).

Moreover, sensory neurons in the skin contribute to barrier function and immune defense against pathogens. They can release neuropeptides that promote inflammation and recruit immune cells to sites of injury, thereby enhancing the body’s capacity to respond to external threats (Mei et al., 2025).

Impacts of Sensory Neurons on Disease Progression

While the PNS has protective roles, it can also contribute to disease progression. For instance, neuropeptides released by sensory neurons may exacerbate inflammation in chronic inflammatory diseases, such as arthritis and asthma (Mei et al., 2025). In cancers, sensory neurons can promote tumor growth by modulating the immune response and supporting the tumor microenvironment (Mei et al., 2025). This underscores the need for a nuanced understanding of sensory neuron functions in both health and disease.

Future Directions in Sensory Nervous System Research

Future research on the PNS should focus on elucidating the mechanisms underlying its diverse functions and exploring potential therapeutic targets for modulating sensory neuron activity. Advances in techniques such as optogenetics and single-cell RNA sequencing will enable researchers to dissect the molecular pathways involved in sensory neuron regulation of organ functions and immune responses (Mei et al., 2025).

Furthermore, understanding the role of sensory neurons in various disease contexts will pave the way for developing novel therapies aimed at harnessing their beneficial functions while mitigating their contributions to pathology.

FAQs

What is the peripheral sensory nervous system?

The peripheral sensory nervous system is a component of the nervous system that collects, processes, and transmits sensory information from the external environment and internal organs to the central nervous system.

What are the primary functions of the peripheral sensory nervous system?

The primary functions include sensing external stimuli such as touch and temperature, monitoring internal physiological states, and regulating organ functions and immune responses.

How do sensory neurons interact with the immune system?

Sensory neurons release neuropeptides and cytokines that modulate the activity of immune cells, forming neuro-immune cell units that regulate local immune responses and maintain tissue homeostasis.

What are the implications of sensory neuron dysfunction in disease?

Dysfunction of sensory neurons can contribute to various diseases, including chronic inflammatory conditions and cancers, by exacerbating inflammation and modulating the immune response.

What are the future directions for research on the peripheral sensory nervous system?

Future research should focus on elucidating the mechanisms of sensory neuron functions, exploring therapeutic targets for modulating sensory neuron activity, and understanding their roles in various disease contexts.

References

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