Formalin Injection Into Knee Joints of Rats: Pharmacologic Characterization of a Deep Somatic Nociceptive Model

Anxiety is thought to influence pain experience in an opposing manner depending on nociception originates in cutaneous or deep somatic/visceral tissues. The present formalin-induced nociceptive test may help to predict more reliably the pain-killing effect of new pharmacologic strategies, with classical or nonclassical mechanisms, for the treatment of clinically relevant pains, which are generally originated in deep structures.