Potentiation of sural nerve Abeta action potential after neurogenic inflammation

A cyclic peptide targeted against PSD-95 blocks central sensitization and attenuates thermal hyperalgesia

Post-synaptic density protein PSD-95 is emerging as a valid target for modulating nociception in animal studies. Based on the key role of PSD-95 in neuronal plasticity and the maintenance of pain behavior, we predicted that CN2097, a peptide-based macrocycle of nine residues that binds to the PSD-95 Discs large, Zona occludens 1 (PDZ) domains of PSD-95, would interfere with physiologic phenomena in the spinal cord related to central sensitization. Furthermore, we tested whether spinal intrathecal injection of CN2097 attenuates thermal hyperalgesia in a rat model of sciatic neuropathy. Results demonstrate that spinal CN2097 reverses hyperexcitability of wide dynamic range (WDR) neurons in the dorsal horn of neuropathic rats and decreases their evoked responses to peripheral stimuli (brush, low caliber von Frey and pressure), whereas CN5125 ("negative control") has no effect. CN2097 also blocks C-fiber long-term potentiation (LTP) in the dorsal horn, which is linked to neuronal plasticity and central sensitization. At a molecular level, CN2097 attenuates the increase in phosphorylated p38 MAPK, a key intracellular signaling pathway in neuropathic pain. Moreover, spinal injection of CN2097 blocks thermal hyperalgesia in neuropathic rats. We conclude that CN2097 is a small molecule peptide with putative anti-nociceptive effects that modulates physiologic phenomena related to central sensitization under conditions of chronic pain.

Lidocaine treatment in pediatric convulsive status epilepticus

BACKGROUND

Convulsive status epilepticus (CSE) may end fatally or leave serious sequelae. CSE treatment, invariably an emergency case, is based upon i.v. benzodiazepines as well as phenytoin, barbiturates or both. The present paper reports efficiency of lidocaine in CSE.

METHODS

The effects of lidocaine on patients with CSE due to infectious and non-infectious reasons were compared. Lidocaine was given in 29 episodes of CSE to 49 patients having failed to respond to first-line anticonvulsive drugs, such as diazepam, phenobarbital and phenytoin therapy. Lidocaine was given in doses of 2 mg/kg bolus i.v., and then in 4 mg/kg per h infusion.

RESULTS

Mean duration of lidocaine infusion was 14.6 +/- 7.8 h. Effectiveness of lidocaine in patients with CSE was found to be 44.4%. Also, 11 patients responded to a single dose of lidocaine (37.9%), while another two (6.9%) required another dose to suppress their seizures. Patients with seizures attributable to infections were observed to have responded favorably to lidocaine when compared to those with seizures due to epilepsy (37.9% vs 6.8%; P < 0.05). Subsequent epilepsy was found to occur more frequently in patients with a poor response to lidocaine than in patients with a good response (P < 0.05). Adverse reactions to lidocaine were observed in three patients (10.3%), two of them having ventricular arrhythmia. As for the other patient, the focal seizure developed into a generalized one.

CONCLUSIONS

Lidocaine seems to be useful for the management of CSE as a rapid-acting anticonvulsant, particularly in patients with CSE due to infections. But further studies with larger number of patients are needed.