ABSTRACT
Annona vepretorum Mart. (Annonaceae) is a species popularly known in Brazil as "araticum" and "pinha da Caatinga". We have evaluated the antinociceptive effects of A. vepretorum in formalin-, capsaicin-, and glutamate-induced orofacial nociception in mice. Male Swiss mice were pretreated with either saline (p.o.), A. vepretorum ethanol extract (Av-EtOH 25, 50 and 100 mg/kg, p.o.), or morphine (10 mg/kg, i.p.), before formalin, capsaicin, or glutamate was injected into the right upper lip. Pre-treatment with Av-EtOH at all doses produced a reduction in face-rubbing behavior induced by formalin in both phases, and these pre-treatments also produced a significant antinociceptive effect in the capsaicin and glutamate tests. Pre-treatment with naloxone (1.5 mg/kg, i.p.) did not reverse the antinociceptive activity of the extract at the dose of 100 mg/kg in the first phase of this test. Our results suggest that Av-EtOH might be useful in the treatment of orofacial pain.
Subject(s)
Analgesics/pharmacology , Annona/chemistry , Facial Pain/prevention & control , Plant Extracts/pharmacology , Plant Leaves/chemistry , Analgesics/chemistry , Animals , Capsaicin , Dose-Response Relationship, Drug , Drug Antagonism , Ethanol/chemistry , Facial Pain/chemically induced , Formaldehyde , Glutamic Acid , Male , Mice , Naloxone/pharmacology , Narcotic Antagonists/pharmacology , Pain Measurement/methods , Phytotherapy , Plant Extracts/chemistryABSTRACT
BACKGROUND: Annona vepretorum Mart. (Annonaceae) is a native tree from Caatinga (Brazilian Northeastern savanna biome), popularly known as "araticum" and "pinha da Caatinga". In this study, we investigated the effects of the crude ethanolic extract (Av-EtOH) in models of pain and inflammation in rodents. METHODS: The evaluation of antinociceptive activity was carried out by the acetic acid-induced writhing, formalin, hot plate and tail flick tests, while paw edema induced by carrageenan or histamine, and leukocyte migration to the peritoneal cavity were used for anti-inflammatory profile. Histological analyses also were carried out. RESULTS: Av-EtOH (25, 50 and 100 mg/kg, p.o) significantly reduced the number of writhing (P < 0.01) and decreased (P < 0.01) the paw licking time in both phases of the formalin test. In the hot plate and tail flick tests, this extract increased the reaction time, consequently reduced painful behavior. The effects in the formalin and hot plate tests were antagonized by naloxone. Av-EtOH inhibited significantly (P < 0.01) the increase in the edema volume after administration of carrageenan and histamine. In the peritonitis test, acute pre-treatment with Av-EtOH inhibited leukocyte migration. Histological analysis showed less inflammation in the groups treated with the extract when the inflammation was induced by carrageenan or histamine. CONCLUSION: Thus, Av-EtOH has significant antinociceptive and anti-inflammatory properties, which are related probably with the activation of opioid receptors and inhibition of release of mediators of the inflammatory process. This specie is a potential target for drug discovery.