Does Mg2+ deficiency induce a long-tenn sensitization of the central nociceptive pathways?

In rats, a Mg2+-deficient diet, which in a few days dramatically decreased the Mg2+ concentration in plasma, cerebrospinal fluid (CSF) and spinal cord, was accompanied by a significant lowering of the nociceptive threshold. After reloading, the Mg2+ concentration was rapidly normalized in both spinal cord and CSF. In parallel, the neurological disturbances induced by Mg2+ deficiency vanished in less that 24 h, but the reversal of the hyperalgesia was delayed for up to 11 to 20 days. In this model, repeated doses of dizocilpine (MK-801), a noncompetitive NNMA receptor antagonist, given at start of the Mg2+-depleted diet, prevented hyperalgesia, suggesting the involvement of NMDA receptor channels. The delayed recovery of a normal pain threshold argues for long-term sensitization of the nociceptive pathways. (C) 2003 Elsevier Science B.V. All rights reserved.