Antinociceptive effects of sinomenine in a rat model of neuropathic pain

Abstract

Sinomenine is a principal ingredient of traditional Chinese medicine, Sinomenium Acutum, which has been reported to have various pharmacological effects including anti-rheumatism and immunomodulation. This study examined the effects of sinomenine in rats that received chronic constriction injury (CCI), a model of peripheral neuropathic pain. CCI injury on the right sciatic nerve led to long-lasting mechanical hyperalgesia. Acute sinomenine treatment (10–40 mg/kg, i.p.) significantly and dose-dependently reversed mechanical hyperalgesia. In addition, the antinociceptive effects of sinomenine remained stable during repeated daily treatment for up to 2 weeks. Although sinomenine did not alter the duration of immobility in the forced swimming test in healthy animals, it dose-dependently reversed the increased immobility time in rats receiving CCI, suggesting that sinomenine attenuated chronic pain-induced depressive-like behavior. The antinociceptive effects of sinomenine were blocked by the GABAa receptor antagonist bicuculine. The doses of sinomenine studied here did not significantly alter the spontaneous locomotor activity. Together, these results suggested that sinomenine exerts significant antinociceptive effects for neuropathic pain via GABAa-mediated mechanism, which suggests that sinomenine may be useful for the management of chronic painful conditions such as neuropathic pain.

Low temperature photoluminescence from disordered granular ZnO

“…Our observation is consistent with the report [11] that 3.313 eV PL emission is quenched for annealing at 800 o C. Some acceptor defects residing at stacking faults are thought to be the origin of this peak [10,27]. Such acceptors, presumably V Zn related complexes, gets recovered [9][10][11] above 700 o C annealing and this peak disappears. A simple consideration (band gap of ZnO at 0 K the peak energy position) yields the binding energy of the acceptor defect as 124±5 meV.…”

“…1c). This particular peak has been found by several authors [6,10,27,30] in ZnO micro or nano crystallites, particularly in powder samples [31]. Our observation is consistent with the report [11] that 3.313 eV PL emission is quenched for annealing at 800 o C. Some acceptor defects residing at stacking faults are thought to be the origin of this peak [10,27].…”

“…A simple consideration (band gap of ZnO at 0 K the peak energy position) yields the binding energy of the acceptor defect as 124±5 meV. This is in conformity with earlier reports [10,11,27] of V Zn related acceptors in ZnO. It is interesting to note that with increasing irradiation induced disorder, this emission intensity does not vary much (Fig.…”

“…During irradiation large scale generation I Zn , V Zn , I O , V O as well as antisite defects take place. Reorganization of defects can increase DBX emission at the cost of 3.313 eV PL emission [10]. As both the donors and acceptors are present in 500U sample, DAP transition is also expected.…”

“…It has 4 been earlier found that defective natures of 500 o C and 800 o C annealed ZnO are quite different [9,10]. Due to annealing at 800 o C, majority of the zinc vacancies (V Zn ) are recovered and oxygen vacancies (V O ) become dominant [9][10][11].…”