Background

Peripheral nerve function is compromised in a range of disorders, including diabetic neuropathy and autoimmune conditions like Guillain-Barré syndrome and chronic inflammatory demyelinating polyneuropathy, as well as hereditary diseases such as Charcot-Marie-Tooth disease [1–4]. Injuries, infections (e.g., Lyme disease, Mycobacterium leprae), vitamin deficiency, and intoxications (e.g., heavy metals) may also lead to nerve damage [3,5,6]. Depending on which nerves and nerve fibers are affected, the symptoms can include pain, numbness, tingling, and weakness, and can alter sensory, motor, or autonomic functions in the body [7]. Nociceptors detect harmful stimuli like extreme temperature, pressure, or injury-related chemicals in the skin. The signal is then converted into electrical impulses sent to the brain, shaping the diverse qualities of pain [8,9].

In vivo electromyography is a long-established method for assessing sensory and motor functions in the peripheral nervous system [10,11]. Conducting nerve studies in live rodents poses several challenges. Muscle activity is often involved, making it difficult to isolate and assess nerve function independently—an important distinction when evaluating effects on nerves vs. muscles. Another challenge with in vivo electrophysiological setups is the impact of anesthetics and blood perfusion, which can interfere with direct pharmacological effects or influence nerve activity. Maintaining physiological temperature is also essential in these setups, as temperature strongly modulates nerve conduction. Finally, the use of a smaller device and low-volume chamber helps minimize noise within the system, improving control and accuracy.

An ex vivo electrophysiology setup for the isolated sciatic nerve is a vital tool in neuroscience research, offering significant insights into nerve function and pathology. The use of suction electrodes, which gently capture nerve fibers to record action potentials is increasingly used to study ex vivo peripheral nerve function [12,13]. However, suction electrodes can be technically difficult to prepare and use. Also, potential amplitude and recording stability strongly depend on both the quality of the suction maintenance and the nerve/electrode resistance [14]. An alternative is the use of a Vaseline-sealed three-chamber-compartment recording technique (Figure 1). This setup enables precise recording of electrical activity from the isolated mouse sciatic nerve, facilitating the study of various disease models and the effects of pharmacological manipulations. Numerous animal models are available to investigate myelin biology, conduction, and the pathological mechanisms underlying conduction defects in peripheral neuropathies. While electromyographic recording offers limited insights into both myelinated and unmyelinated fiber populations, ex vivo recordings of nerve trunks provide a valuable opportunity to examine specific alterations in axonal populations and conduct selective pharmacological studies. This electrophysiological setup evaluates the conduction properties of the sciatic nerve by stimulating the distal end, replicating pain-related signals, and enabling functional analysis of nerve fibers (Figure 1). Key findings include: (1) Conduction velocity: differentiates large fibers (Aβ, Aδ) from small fibers (C), essential for studying nociceptive and mechanosensitive pathways. (2) Amplitude: reflects nerve fiber activity and recruitment potential, which can be altered under conditions such as pain or inflammation. (3) Refractory period: reveals nerve recovery and firing capacity, critical for understanding pain-related repetitive firing. (4) Excitability changes: hyper- and hypo-excitability, which are linked to allodynia and hypoesthesia. By maintaining the viability of the isolated nerve for extended periods, researchers can conduct long-term experiments, enabling detailed investigations into nerve conduction and the impact of therapeutic interventions. This capability is essential for advancing our understanding of neurological diseases and developing new treatments.