[Pharmacological correction of pain sensitivity threshold in magnesium deficiency]

The purpose of this study was to compare effect of: Mg L-aspartate and MgCl2 alone and in combination with pyridoxine (B6) on hyperalgesia in rats fed with Mg-deficient diet. To induce hypomagnesemia, two hundred rats were placed on a Mg-deficient diet (MP Biomedicals Inc., OH) and demineralized water. To evaluate pain sensitivity, motor and vocalization threshold in response to a mechanical stimulus (Randall-Selitto paw pressure test) and tail withdrawal, simple and brief vocalization threshold in response to an electrical stimulation (algesimetry by electrical stimulation of the tail through intracutaneous needles) were assessed. In our study Mg deficiency results in reduced vocalization threshold by 42% in response to a mechanical stimulus. Thresholds of motor tail response, simple vocalization and brief vocalization after discharge in response to an electrical stimulation were decreased by 32.5%, 20.5% and 23.8%. Oral magnesium salts led to normalization of thresholds of pain sensitivity with a return to pre-deficient levels. Magnesium salts in combinations with pyridoxine tended to be significantly more effective in Randall-Selitto paw pressure test as compared with salts without pyridoxine. The effect of studied salts was comparable with those observed in Magne B6 treatment and significantly higher than in magnesium sulfate treatment.