ISSN:
1432-136X
Schlagwort(e):
Melanosome aggregation
;
Signal transduction
;
Adenylate cyclase activity
;
Second messenger
;
Fish, Carassius auratus
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Biologie
,
Medizin
Notizen:
Abstract The signal-transduction system that mediates the melanosome-aggregating response in melanophores of the black-moor goldfish, Carassius auratus, was investigated by examining the inhibition of adenylate cyclase activity mediated by α-adrenoceptors in cultured cells. When the melanophores were incubated with 1 mmol·l-1 3-isobutyl-1-methylxanthine for 5 min, the intracellular level of cyclic adenosine-3′,5′-monophosphate increased two- to three-fold. Norepinephrine at 100 nmol·l-1 and naphazoline at 1 μmol·l-1 inhibited the 3-isobutyl-1-methylxanthine-induced accumulation of cyclic adenosine-3′,5′-monophosphate in the cells in both the presence and the absence of isoproterenol, a β-adrenergic agonist. Methoxamine and phenylephrine also reduced the extent of accumulation of cyclic adenosine-3′,5′-monophosphate, but only when they were present at relatively high concentrations (above 100 μmol·l-1). The range of concentrations at which norepinephrine inhibited the accumulation of cyclic adenosine-3′,5′-monophosphate was consistent with the range at which it induced the aggregation of melanosomes. Pretreatment of the cells with pertussis toxin (1 μg·ml-1) for 15 h or treatment with 100 nmol·l-1 yohimbine (an α2-adrenergic antagonist) inhibited the effects of the α-adrenergic agonists on both the aggregation of melanosomes and the 3-isobutyl-1-methylxanthine-induced accumulation of cyclic adenosine-3′,5′-monophosphate, but prazosin (an α1adrenergic antagonist) at 100 nmol·l-1 was not inhibitory. These results indicate that the melanosome-aggregating response of the goldfish melanophore is induced mainly via inhibition of the activity of adenylate cyclase, which occurs as result of stimulation of a pathway that involves α1adrenergic and a inhibitory GTP-binding protein.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF00302111
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