Exogenous interleukin-6 increases cold allodynia in rats with a mononeuropathy.

Interleukin-6 (IL-6) is a pleiotropic cytokine, signaling intracellularly via its unique membrane-bound receptor IL-6R and gp130. In peripheral nerve injury models, IL-6 and IL-6R are increased at the injured nerve and the respective dorsal root ganglion. IL-6 is increased at the ipsilateral dorsal and ventral horn of the spinal cord.

Adrenalectomy affects pain behavior of rats after formalin injection.

Stressful stimuli can activate the hypothalamo-pituitary-adrenal-axis and the endogenous opioid system. In addition, corticosterone and opioid release might cause analgesia. This rat study used adrenalectomy for corticosterone withdrawal and naloxone administration for opioid antagonism in order to study pain behavior and hypophyseal hormone release in the plasma after a formalin test.

Interleukin-6 and perioperative thermoregulation and HPA-axis activation.

Surgery is followed by an acute-phase response, including hypothalamo-pituitary-adrenal (HPA)-axis activation and fever. Considering its physiological properties and its behaviour in plasma after stress and surgery, the pro-inflammatory cytokine interleukin (IL)-6 is a putative candidate in eliciting these stress-related symptoms. However, evidence for this hypothesis is lacking.

The role of interleukin-6 in nociception and pain.

That IL-6 is an interesting target in the study of pain is underscored by its biomolecular properties, its localization after experimental pain, and its modulating effect on pain after administration.