CHROMATOSOME-DISPERSING HORMONE 



New observations on the pharmacology of melanophores or of 

 the melanosome-dispersing hormone. — Shen (1937) has studied 

 the effects of a number of drugs on the behavior of the gran- 

 ules of pigment in the melanophores of the skin of frogs. 

 Substances like F 933 and F 883^ bring about marked dis- 

 persion of the melanosomes, provided that the pituitary is 

 intact. After hypophysectomy, "expansion" of the melano- 

 phores does not appear. The conditions under which chlo- 

 ralosane, nicotine, or yohimbine cause melanosome disper- 

 sion are similar. Therefore, all these substances appear to 

 act either by increasing the rate of secretion of the hormone 

 or by markedly potentiating its peripheral effects or by both 

 mechanisms. Shen found that melanosome concentration is 

 reversed by F 933, if it is due to epinephrine but not if it fol- 

 lows stimulation of "pigmento-motor" nerves. Hence, in 

 respect of a congregating effect on the melanosomes, he de- 

 scribes F 933 as a substance which is adrenolytic but not 

 sympatholytic. The injection of either atropine sulphate or 

 ergotamine tartrate into normal frogs adapted to a dark 

 background is followed by paling;' in hypophysectomized 

 frogs, however, either drug causes some melanosome disper- 

 sion. The author's experiments yield no specific information 

 on the possible importance of effects on the secretion or 

 peripheral action of a hormone of the pars tuberalis in rela- 

 tion to melanosome concentration. Hypophysectomy does 

 not affect the dispersion of the melanosomes which is the re- 

 sult of the administration of amyl nitrite, chloroform, ether, 

 or strychnine. 



According to Jores (1935), the injection of extract contain- 

 ing melanophore hormone into rabbits by either an intra- 

 ventricular or an intravenous route is followed by a fall in 



*F933: piperidino-methyl-3-benzodioxane; F 883: diethylamino-methyl-3-ben- 

 zodioxane. 



'The injection of ergometrine," Ephetonin" (synthetic ephedrine), or lobeline is 

 followed by a similar effect. 



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