title: On the role of histamine receptors in regulating pigmentary responses in Oreochromis mossambicus melanophores.
abstract: OBJECTIVE
  The present work was carried out to reveal the involvement of histamine receptors at the neuro-melanophore junction of teleost, Oreochromis mossambicus.
  
  
  METHODS
  The isolated scale melanophores were assayed using the mean melanophore size index and their responses were recorded in presence of various concentrations of histamine along with H(1) and H(2) receptor specific agonists and antagonist and potentiator compound 48/80.
  
  
  RESULTS
  Melanophores showed high sensitivity to histamine and its specific agonists. Histamine caused a dose-dependent pigment aggregation, whereas 2-(2-Pyridyl) ethylamine (PEA), a specific H(1)R agonist also caused aggregation in a similar manner. Conversely, amthamine, a specific H(2)R agonist resulted in pigment dispersion. The effects were antagonized by mepyramine; specific H(1)R antagonist and ranitidine a specific H(2)R antagonist.
  
  
  CONCLUSIONS
  It is concluded that O. mossambicus melanophores have both H(1) and H(2) receptors which mediate melanophore aggregation and dispersion respectively. Compound 48/80 augmented the melanin-aggregating and dispersing effects of PEA and amthamine. It is suggested that the effect of histamine is directly mediated through H1 and H2 receptors, whereas H1Rs may be predominantly involved in the aggregatory responses.
authors.affiliation: Saifia College of Science and Education, Department of Biotechnology, Bhopal, MP, India.
authors.forename: Saima
authors.initials: S
authors.lastname: Salim
authors.forename: Ayesha S
authors.initials: AS
authors.lastname: Ali
authors.forename: Sharique A
authors.initials: SA
authors.lastname: Ali
mesh_terms: D000818:Animals; D005260:Female; D006632:Histamine / Q000737:chemistry / Q000378:metabolism; D017442:Histamine Agonists / Q000494:pharmacology; D006633:Histamine Antagonists / Q000494:pharmacology; D008297:Male; D008543:Melanins / Q000096:biosynthesis / Q000378:metabolism; D008547:Melanophores / Q000187:drug effects / Q000378:metabolism; D010860:Pigments, Biological / Q000378:metabolism; D011738:Pyrilamine / Q000494:pharmacology; D011969:Receptors, Histamine H1 / Q000378:metabolism*; D011970:Receptors, Histamine H2 / Q000378:metabolism*; D013844:Thiazoles / Q000494:pharmacology; D017210:Tilapia / Q000378:metabolism / Q000502:physiology; D003189:p-Methoxy-N-methylphenethylamine / Q000494:pharmacology
chemical_list: D017442:Histamine Agonists; D006633:Histamine Antagonists; D008543:Melanins; D010860:Pigments, Biological; D011969:Receptors, Histamine H1; D011970:Receptors, Histamine H2; D013844:Thiazoles; C076207:amthamine; D003189:p-Methoxy-N-methylphenethylamine; D006632:Histamine; D011738:Pyrilamine