Understanding Free Nerve Endings of Sensory Neurons and Their Role in Neurogenic Inflammation

In the human body, peripheral tissue damage can trigger a series of complex physiological responses, including inflammation. One lesser-known mechanism of neurogenic inflammation involves the release of active neuropeptides from sensory neurons, leading to an inflammatory reaction.

Under normal circumstances, when the body experiences tissue damage, sensory neurons send electrical impulses through the dorsal root ganglion into the central nervous system (CNS) for further processing. However, in cases where neurogenic inflammation occurs, this process is disrupted, and instead, nerve fibers release active neuropeptides such as substance P and calcitonin gene-related peptide (CGRP) rapidly into the microenvironment.

These released neuropeptides trigger a series of inflammatory responses, including erythema, swelling, temperature increase, tenderness, and pain. The majority of these responses are mediated by unmyelinated afferent somatic C-fibers, which respond to low-intensity mechanical and chemical stimulations.

In fibromyalgia, neurogenic inflammation plays a crucial role in the development and maintenance of symptoms. Neurogenic inflammation is characterized as the physiological process by which mediators are released directly from cutaneous nerves to initiate an inflammatory reaction.

The distinction between neurogenic inflammation and immunologic inflammation lies in their mechanisms of action. While both types of inflammation can occur concurrently, they have different underlying causes and manifestations. Immunogenic inflammation is a natural response generated by the immune system when pathogens enter the body, whereas neurogenic inflammation involves a direct relationship between the nervous system and inflammatory reactions.

Understanding the mechanisms of neurogenic inflammation is essential for appreciating its involvement in various clinical conditions. By recognizing the key role played by free nerve endings of sensory neurons, researchers can better comprehend the complex interactions between the nervous system and the immune system, ultimately leading to the development of more effective treatments for conditions such as fibromyalgia.

In summary, neurogenic inflammation is a vital process that plays a crucial role in various physiological responses, including pain perception. The release of active neuropeptides from sensory neurons triggers an inflammatory reaction, which can lead to symptoms such as erythema, swelling, and pain. A deeper understanding of free nerve endings of sensory neurons and their role in neurogenic inflammation is essential for the diagnosis and management of conditions characterized by chronic pain and inflammation.

Free nerve endings of sensory neurons