The sympathetic neuro-melanophore transmission in a fresh-water Indian major carp, Labeo rohita (Ham.).

Adrenaline was effective in aggregating the melanosomes both in innervated as well as denervated melanophores. Isotonic KCl could induce pigment aggregation only in innervated melanophores. Adrenaline- and K+-induced pigment aggregation response in these melanophores was blocked by phentolamine: propranolol failed to do so. It is suggested that the chromatic nerves in the fish, Labeo rohita are adrenergic and via post-synaptic alpha-adrenoceptors, control the melanosome aggregation.