BPR1M492

The formalin-induced paw inflammation/nociceptive test is a chemical persistent pain model in rodents in which subcutaneous injection of formalin into the hind paw produces spontaneous nocifensive behaviors such as flinching and licking. The response is classically biphasic, consisting of an early acute phase (Phase I) reflecting direct activation of peripheral nociceptors (particularly C-fiber afferents), followed by a later prolonged phase (Phase II) associated with central sensitization in the spinal dorsal horn driven by sustained afferent input and inflammatory signaling. This model is widely used to evaluate analgesic and anti-inflammatory interventions because it captures both peripheral nociception and central sensitization processes within a single assay system.

Ca²⁺ staining is an experimental technique that utilizes specific fluorescent probes (such as Fluo-4 AM, Fura-2, etc.) to qualitatively or quantitatively detect dynamic changes in intracellular Ca²⁺ concentrations; this is achieved by monitoring the changes in fluorescent signals generated when these probes bind to free intracellular calcium ions. The underlying principle relies primarily on the presence of chelating groups within the probe's molecular structure that possess high affinity for calcium ions.