Antinociceptive effect of Zanthoxylum rhoifolium Lam. (Rutaceae) in models of acute pain in rodents

AIM OF THE STUDY

Zanthoxylum rhoifolium Lam. (Rutaceae) is locally known as "mamica de cadela", and its bark is popularly used for toothache and earache. The objective of this study was to investigate the antinociceptive effect of the ethanolic extract from this species' stem bark (EtOH), its fractions of partition (hexane-HEX, ethyl acetate-AcOEt, aqueous-AQ) and lupeol (a triterpene obtained from HEX) in models of acute pain.

MATERIALS AND METHODS

Male and female Swiss mice (25-35 g, n=6-12 animals/group) were used to assess acute toxicity and nociception (Animal Ethics Committee/UFPI, No. 09/2008). Acute toxicity was studied up to 2 g/kg p.o. of EtOH. In the formalin test (2%, 20 microL/paw), the licking time of the stimulated paw was quantified during the first 5 min (first phase) and at 15-30 min (second phase), 1h after oral treatment with EtOH, HEX, AcOEt or saline, and 30 min after use of morphine-MOR (5 mg/kg i.p.). The same response evoked by capsaicin (2 microg/20 microL/paw) was quantified during 5 min, after administration of EtOH, HEX, AcOEt, AQ, saline and MOR. The licking time of the paw that was stimulated with glutamate (10 micromol/20 microL) was measured (15 min) after treatment with EtOH, HEX, AcOEt, AQ, lupeol, saline or MK801 (0.03 mg/kg, i.p.). Mice were submitted to the rota-rod task and open-field test in order to assess any non-specific muscle-relaxant or sedative effects of EtOH (250 mg/kg p.o.) and HEX (500 mg/kg p.o.).

RESULTS

The animals did not exhibit any acute toxicity to EtOH (up to 2 g/kg p.o.), so it was not possible to calculate the LD50. EtOH, HEX and AcOEt (62.5-250 mg/kg) produced a significant antinociceptive effect in the formalin and capsaicin tests. However, AQ was ineffective. EtOH, HEX, AcOEt and lupeol reduced the glutamate-evoked nociceptive response, but AQ had no effect. EtOH and HEX did not alter the locomotion of animals in the open-field or rota-rod tests, which suggest a lack of a central depressant effect.

CONCLUSION

The results confirm the popular use of Zanthoxylum rhoifolium as an analgesic, and contribute to the pharmacological knowledge of this species because it was shown that EtOH and its less polar partition fractions (HEX, AcOEt) have an antinociceptive effect in models of chemical nociception, and that lupeol appears to be one of the constituents responsible for this effect.

[Remuneration and productivity: the case of the Minas Gerais Hospital Foundation, Brazil, 1992-1995]

This article presents an analysis of the Minas Gerais State Hospital Foundation immediately after the introduction in its health services units in early 1993 of a new system of rewards for good performance and productivity, as a complement to salaried remuneration. Analysis was based on a cross-sectional study of changes in indicators of production and productivity in the Foundation during the 1992-1995 period. Data were obtained from hospitalization authorization forms, payment authorization guides, and bulletins from the Human Resource Administration. The strategy of conditional remuneration and incentives was adopted not only to step up production and productivity, but also to increase the employees' commitment to the institution. Analysis of the selected indicators appears to confirm other study results in that remuneration based on results (conditional incentives) leads to a positive change in the production level of services and productivity, even if it does not last for the long term. Study results also support the notion that such alternatives may be deliberately used as part of a more general strategy of organizational development and not only as an isolated element for concrete improvements in productivity.