Modulation of pig epidermal adenylate-cyclase responses by protein-synthesis inhibitors: Its relation to glucocorticoid and colchicine effects

Publisher Website
Google Scholar
Abstract
The effects of protein-synthesis inhibitors (actinomycin D, puromycin, and cycloheximide) on epidermal adenylate-cyclase responses were investigated. When pig skin (epidermis) was incubated in RPMI-1640 medium, the β-adrenergic adenylatecyclase response (epinephrine-induced cyclic-AMP accumulations) decreased, whereas the adenosine and histamine responses increased after long-term (up to 48 h) incubation. The addition of actinomycin D or puromycin to the incubation medium resulted in a marked increase in epinephrine-induced cyclic-AMP accumulations and a decrease in adenosine- and histamine-induced cyclic-AMP accumulations. Cycloheximide had a weak effect on the epinephrine response, and had apparently stronger effects on the adenosine and histamine responses than actinomycin D or puromycin. Histologically, various degenerative changes of keratinocytes (with or without acantholytic changes) were observed after long-term incubation with these protein-synthesis inhibitors. Both low- and high-K m cyclic-AMP phosphodiesterase activities were moderately decreased by the protein-synthesis inhibitors. However, augmentation effects on the β-adrenergic response were also observed in the presence of the cyclic-AMP phosphodiesterase inhibitor, theophylline. We have described previously similar augmentation effects on the β-adrenergic response caused by glucocorticoids and colchicine. Comparison of the effects of these chemicals with those of protein-synthesis inhibitors revealed that the most marked effects on the β-adrenergic response were produced by actinomycin D, puromycin and colchicine; glucocorticoid had a moderate effect (hydrocortisone), while cycloheximide had only a weak effect. Furthermore, the simultaneous addition of actinomycin D (or puromycin) and colchicine (or hydrocortisone) at their optimal concentrations produced a more marked (additive or synergistic) increase in the β-adrenergic response than the addition of each chemical alone. The simutaneous addition of actinomycin D and puromycin at their optimal concentrations resulted in neither an additive nor a synergistic effect. Our results indicate that, as well as being affected by glucocorticoids and colchicine, epidermal adenylatecyclase responses are affected by various protein-synthesis inhibitors, the mechanism of which seems to be independent of that of glucocorticoids or colchicine.