title: Mediation of cholino-piperine like receptors by extracts of Piper nigrum induces melanin dispersion in Rana tigerina tadpole melanophores.
abstract: OBJECTIVE
  The present study was carried out to determine the effects of lyophilized dried fruit extracts of Piper nigrum and pure piperine on the tadpole melanophores of frog Rana tigerina which offer excellent in vitro opportunities for studying the effects of pharmacological and pharmaceutical agents. The nature of specific cellular receptors present on the neuro-melanophore junction and their involvement in pigmentary responses has been explored.
  
  
  METHODS
  Effects of lyophilized extracts of P. nigrum and pure piperine were studied on the isolated tail melanophores of tadpoles of the frog R. tigerina as per the modified method.
  
  
  RESULTS
  The extract of P. nigrum and its active ingredient piperine caused significant melanin dispersal responses leading to darkening of the tail melanophores, which were completely antagonized by atropine and hyoscine. These per se melanin dispersal effects were also found to be markedly potentiated by neostigmine an anticholinesterase agent.
  
  
  CONCLUSIONS
  It appears that the melanin dispersal effects of the extracts of P. nigrum and pure piperine leading to skin darkening are mediated by cholinergic muscarinic or piperine-like receptors having similar properties.
authors.affiliation: Postgraduate Department of Biotechnology, Saifia College of Science, Bhopal, India.
authors.forename: Mohammed
authors.initials: M
authors.lastname: Sajid
authors.forename: Sharique A
authors.initials: SA
authors.lastname: Ali
mesh_terms: D000109:Acetylcholine / Q000378:metabolism; D000470:Alkaloids / Q000737:chemistry / Q000494:pharmacology*; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D052117:Benzodioxoles / Q000737:chemistry / Q000494:pharmacology*; D002086:Butylscopolammonium Bromide / Q000494:pharmacology; D002800:Cholinesterase Inhibitors / Q000494:pharmacology; D007814:Larva / Q000166:cytology*; D008543:Melanins; D008547:Melanophores / Q000187:drug effects* / Q000378:metabolism; D015394:Molecular Structure; D018727:Muscarinic Antagonists / Q000494:pharmacology; D009388:Neostigmine / Q000494:pharmacology; D029222:Piper nigrum / Q000737:chemistry*; D010880:Piperidines / Q000737:chemistry / Q000494:pharmacology*; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology*; D053284:Polyunsaturated Alkamides / Q000737:chemistry / Q000494:pharmacology*; D011898:Ranidae / Q000502:physiology*; D011950:Receptors, Cholinergic / Q000378:metabolism*
chemical_list: D000470:Alkaloids; D052117:Benzodioxoles; D002800:Cholinesterase Inhibitors; D008543:Melanins; D018727:Muscarinic Antagonists; D010880:Piperidines; D010936:Plant Extracts; D053284:Polyunsaturated Alkamides; D011950:Receptors, Cholinergic; D002086:Butylscopolammonium Bromide; D009388:Neostigmine; D001285:Atropine; D000109:Acetylcholine; C008922:piperine