title: Pharmacological basis for the medicinal use of psyllium husk (Ispaghula) in constipation and diarrhea.
abstract: BACKGROUND
  The objective of this study was to determine the pharmacological basis of the medicinal use of psyllium husk (Ispaghula) in gastrointestinal motility disorders.
  
  
  METHODS
  In-vivo studies were conducted on mice, and isolated rabbit jejunum and guinea-pig ileum were used in in-vitro experiments.
  
  
  RESULTS
  The crude extract of Ispaghula (Po.Cr) had a laxative effect in mice at 100 and 300 mg/kg, which was partially sensitive to atropine or SB203186 (5-HT(4) antagonist). At higher doses (500 and 1,000 mg/kg), Po.Cr had antisecretory and antidiarrheal activity. In guinea-pig ileum, Po.Cr (1-10 mg/ml) had a stimulatory effect, which was partially sensitive to atropine or SB203186. In rabbit jejunum, Po.Cr had a partially atropine-sensitive stimulatory effect followed by relaxation at 10 mg/ml. The relaxation was inhibited by the presence of L-NAME, a nitric oxide (NO) synthase inhibitor, or methylene blue, a guanylyl cyclase inhibitor. Similarly, the relaxant effect of Po.Cr on K(+) (80 mM)-induced contractions, was attenuated in the presence of L-NAME or methylene blue. Activity-directed fractionation of Po.Cr revealed that the gut stimulatory and inhibitory constituents were widely distributed in the aqueous and organic fractions.
  
  
  CONCLUSIONS
  This study demonstrates that Ispaghula has a gut-stimulatory effect, mediated partially by muscarinic and 5-HT(4) receptor activation, which may complement the laxative effect of its fiber content, and a gut-inhibitory activity possibly mediated by blockade of Ca(2+) channels and activation of NO-cyclic guanosine monophosphate pathways. This may explain its medicinal use in diarrhea. It is, perhaps, also intended by nature to offset an excessive stimulant effect.
authors.affiliation: Natural Product Research Division, Department of Biological and Biomedical Sciences, Aga Khan University Medical College, Karachi, 74800, Pakistan. hassan.mehmood@aku.edu
authors.forename: Malik Hassan
authors.initials: MH
authors.lastname: Mehmood
authors.forename: Nauman
authors.initials: N
authors.lastname: Aziz
authors.forename: Muhammad Nabeel
authors.initials: MN
authors.lastname: Ghayur
authors.forename: Anwarul-Hassan
authors.initials: AH
authors.lastname: Gilani
mesh_terms: D000818:Animals; D001127:Arginine Vasopressin / Q000031:analogs & derivatives / Q000187:drug effects; D003248:Constipation / Q000188:drug therapy*; D003967:Diarrhea / Q000188:drug therapy*; D005260:Female; D006168:Guinea Pigs; D007583:Jejunum / Q000187:drug effects; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology; D011620:Psyllium / Q000494:pharmacology*; D011817:Rabbits; D014700:Verapamil / Q000494:pharmacology
chemical_list: D010936:Plant Extracts; C056685:argipressin, beta-mercapto(beta,beta)-cyclopentamethylenepropionic acid(1)-Ile(2,4)-; D001127:Arginine Vasopressin; D011620:Psyllium; D014700:Verapamil