In vitro response of goldfish (Carassius auratus L.) dermal melanophores to cyclic 3, 5′-nucleotides, nucleoside 5′-phosphates and methylxanthines
✍ Scribed by Joel Abramowitz; Walter Chavin
- Publisher
- John Wiley and Sons
- Year
- 1974
- Tongue
- English
- Weight
- 724 KB
- Volume
- 84
- Category
- Article
- ISSN
- 0021-9541
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✦ Synopsis
Abstract
cAMP, dbcAMP, cCMP, cGMP, theophylline and caffeine caused reversible melanosome dispersion within 5 minutes at 10 mM in the dermal melanophores of the black goldfish, Carassius auratus L. cTMP, cUMP, 5′‐AMP, 5′‐CMP, 5′‐GMP, 5′‐TMP, and 5′‐UMP did not produce melanosome dispersion or aggregation in this melanophore system. cAMP was the most effective nucleotide in the induction of melanosome dispersion; at 10 mM, cGMP and at 5 mM, dbcAMP were the least effective of those nucleotides inducing melanosome dispersion. At the 10 mM level dbcAMP required 30 minutes to evoke the same degree of melanosome dispersion as 5 minutes cAMP treatment. Theophylline was more effective than caffeine in eliciting melanosome dispersion. At 1 mM, theophylline and caffeine first induced melanosome dispersion which was followed by aggregation in the course of the 30 minute test period. These reactions suggest both a high melanophore phosphodiesterase activity and competitive inhibition of phosphodiesterase by theophylline and caffeine. Induction of melanosome dispersion by several cyclic 3′,5′‐nucleotides suggest multi‐nucleotide control of melanosome dispersion. These findings also support a proposed mechanism of prostaglandin induced melanosome dispersion as well as the “second messenger” hypothesis.