title: The stem bark extracts of Cenostigma macrophyllum attenuates tactile allodynia in streptozotocin-induced diabetic rats.
abstract: CONTEXT. Cenostigma macrophyllum Tul. var. acuminata Teles Freire (Leguminosae- Caesalpinioideae) is popularly known as "caneleiro". Previous studies showed antioxidant action and analgesic effects of the ethanol extract from the leaves of C. macrophyllum. The phytochemical evaluation of the stem bark revealed the presence of antinociceptive compounds.
  
  
  OBJECTIVE
  To investigate the antinociceptive actions of the ethanol extract and ethyl acetate fraction from C. macrophyllum stem bark in streptozotocin (STZ)-induced diabetic rats and the involvement of opioid and nitrergic mechanisms.
  
  
  METHODS
  STZ-rats received the ethanol extract (E.EtOH 200 and 300 mg/kg, p.o.) during 5 weeks. In acute experiments, untreated diabetic rats were treated with the ethyl acetate fraction (F.EtOAc 250 and 500 mg/kg, p.o.), on the 28th day of diabetes induction when the opioid and nitrergic mechanisms were investigated. The mechanical nociceptive threshold (MNT) was determined by application of von Frey filaments.
  
  
  RESULTS
  Data show that STZ-induced diabetic rats developed a significant tactile allodynia during 5 weeks. Diabetic rats that received E.EtOH (200 and 300 mg/kg) and F.EtOAc (250 and 500 mg/kg) had a pain threshold higher than those in the STZ-vehicle group. F.EtOAc effects were inhibited by pretreatment with naloxone and were not influenced by .-arginine.
  
  
  CONCLUSIONS
  The results suggest that the ethanol extract and ethyl acetate fraction of C. macrophyllum presented antinociceptive activity. Thus, F.EtOAc may be exerting its effect by affecting the opioid system, but nitrergic mechanisms are not detectable. The observed activity may be due to its gallic acid, lupeol and bergenin content.
authors.affiliation: Department of Biochemistry and Pharmacology, Federal University of Piaui, Teresina-PI, Brazil.
authors.forename: Celyane Alves
authors.initials: CA
authors.lastname: Piaulino
authors.forename: Fernanda Cerqueira Barroso
authors.initials: FC
authors.lastname: Carvalho
authors.forename: Buana Carvalho
authors.initials: BC
authors.lastname: Almeida
authors.forename: Mariana Helena
authors.initials: MH
authors.lastname: Chaves
authors.forename: Fernanda Regina Castro
authors.initials: FR
authors.lastname: Almeida
authors.forename: Salete Maria Rocha Cipriano
authors.initials: SM
authors.lastname: Brito
mesh_terms: D000085:Acetates / Q000737:chemistry; D000700:Analgesics / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D000818:Animals; D003921:Diabetes Mellitus, Experimental / Q000150:complications / Q000188:drug therapy*; D003929:Diabetic Neuropathies / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology / Q000517:prevention & control*; D000431:Ethanol / Q000737:chemistry; D007887:Fabaceae / Q000737:chemistry; D006930:Hyperalgesia / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology / Q000517:prevention & control*; D008297:Male; D009270:Naloxone / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D026602:Nitrergic Neurons / Q000187:drug effects / Q000378:metabolism; D018847:Opioid Peptides / Q000378:metabolism; D017288:Pain Threshold / Q000187:drug effects; D008517:Phytotherapy; D024301:Plant Bark; D010936:Plant Extracts / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D018547:Plant Stems; D010946:Plants, Medicinal; D051381:Rats; D017208:Rats, Wistar; D011957:Receptors, Opioid / Q000378:metabolism; D012997:Solvents / Q000737:chemistry; D013997:Time Factors
chemical_list: D000085:Acetates; D000700:Analgesics; D009292:Narcotic Antagonists; D018847:Opioid Peptides; D010936:Plant Extracts; D011957:Receptors, Opioid; D012997:Solvents; D009270:Naloxone; D000431:Ethanol; C007650:ethyl acetate