RESUMO
Curcumin, a curcuminoid from Curcuma longa, presents antioxidant and anti-inflammatory actions and, among pathological changes of cerebral ischemic injury, inflammation is an important one. The objectives were to study the neuroprotective action of curcumin, in a model of global ischemia. Male Wistar rats (sham-operated, ischemic untreated and ischemic treated with curcumin, 25 or 50 mg/kg, p.o.) were anesthesized and their carotid arteries occluded, for 30 min. The SO group had the same procedure, except for carotid occlusion. In the 1st protocol, animals were treated 1 h before ischemia and 24 h later; and in the 2nd protocol, treatments began 1 h before ischemia, continuing for 7 days. Twenty four hours after the last administration, animals were euthanized and measurements for striatal monoamines were performed, at the 1st and 7th days after ischemia, as well as histological and immunohistochemical assays in hippocampi. We showed in both protocols, depletions of DA and its metabolites (DOPAC and HVA), in the ischemic group, but these effects were reversed by curcumin. Additionally, a decrease seen in 5-HT contents, 1 day after ischemia, was also reversed by curcumin. This reversion was not seen 7 days later. On the other hand, a decrease observed in NE levels, at the 7th day, was totally reversed by curcumin. Furthermore, curcumin treatments increased neuronal viability and attenuated the immunoreactivity for COX-2 and TNF-alpha, in the hippocampus in both protocols. We showed that curcumin exerts neuroprotective actions, in a model of brain ischemia that are probably related to its anti-inflammatory activity.
RESUMO
Piperine, an alkaloid present in the Piper genus, was shown to have an anticonvulsant activity, evaluated by the pilocarpine-induced model, in mice. Pilocarpine (350mg/kg, i.p.) was administered 30min after piperine (2.5, 5, 10 and 20mg/kg, i.p.) which significantly increased latencies to 1st convulsion and to death, and percentage of survivals. These parameters were also increased in the pilocarpine groups pretreated with atropine plus piperine (10 and 2.5mg/kg, respectively), as related to the pilocarpine group. However, they were not altered in the pilocarpine groups pretreated with memantine (a NMDA-type glutamate receptors blocker, 2mg/kg, p.o.) or nimodipine (a calcium channel blocker, 10mg/kg, p.o.), both associated with piperine (1 or 2.5mg/kg), as compared to the piperine plus pilocarpine group. Moreover, the pilocarpine group pretreated with diazepam (which binds to the GABAA receptor, 0.2 and 0.5mg/kg, i.p.) plus piperine (1 and 2.5mg/kg) significantly increased latency to the 1st convulsion, as related to the pilocarpine group, suggesting that the GABAergic system is involved with the piperine action. Furthermore, the piperine effect was blocked by flumazenil (2mg/kg, i.p.), a benzodiazepine antagonist. Untreated P350 animals showed decreased striatal DA and increased DOPAC and HVA levels that were not affected in the piperine plus pilocarpine groups. Piperine increased striatal levels of GABA, glycine and taurine, and reversed pilocarpine-induced increases in nitrite contents in sera and brain. Hippocampi from the untreated pilocarpine group showed an increased number of TNF-α immunostained cells in all areas, as opposed to the pilocarpine group pretreated with piperine. Taken together, piperine anticonvulsant effects are the result of its anti-inflammatory and antioxidant actions, as well as TNF-α reduction. In addition, piperine effects on inhibitory amino acids and on the GABAergic system may certainly contribute to the drug anticonvulsant activity.
