Meire Nakamura-Craig | PubMed Health

PubMed1995

Effect of lamotrigine in the acute and chronic hyperalgesia induced by PGE2 and in the chronic hyperalgesia in rats with streptozotocin-induced diabetes.

There is still a need for a new analgesic devoid of the side effects presented by opioids or non-steroidal anti-inflammatory drugs, for the treatment of some acute and chronic pain conditions. Lamotrigine (Lamictal1, 10-100 mg/kg), a new anticonvulsant, showed analgesic effects in the acute model of prostaglandin E2 (PGE2)-induced hyperalgesia when given orally before or after the subplantar injection of PGE2 in the rat. It also inhibited the development of sustained hyperalgesia induced by multiple subplantar injections of PGE2 when administered orally prior to the PGE2 injections. Furthermore, lamotrigine induced analgesia in the model of chronic hyperalgesia in streptozotocin-induced diabetic rats. The effects of carbamazepine and phenytoin are compared to the effects of lamotrigine in this model. The results suggest that lamotrigine could be used in pain conditions where neuronal sensitization may be present and possibly also where it could inhibit the development of this sensitization.

Acute Disease↗

PubMed1989

Substance P and peripheral inflammatory hyperalgesia.

The hyperalgesic effect of substance P (SP) is usually described as presenting short latency. We now report that multiple injections of sub-threshold doses of SP into the foot pad of a hind paw of rats pre-treated with indomethacin induced a long-lasting hyperalgesia, sensitizing the paw to further challenges with small doses of SP, dopamine or prostacyclin. The sensitizing process also occurred after multiple injections of prostacyclin or prostaglandin E2. The sensitizing effect induced by SP, prostaglandin E2 or prostacyclin is inhibited by pre-treatment with the SP antagonist (D-Arg, D-Pro, D-Trp, Leu)-SP. We suggest that SP has an important role as a modulator in peripheral inflammatory pain by sensitizing nociceptors to its own action and to the action of different mediators. This sensitizing process could also be associated with chronic inflammatory pain.

Animals↗