Effects of stimulation of the parasympathetic and sympathetic innervations in bursts on the syntheses of polyamines, DNA and protein in salivary glands of the rat: non-adrenergic, non-cholinergic responses.

The increase in the activity of ornithine decarboxylase, the key enzyme in the formation of polyamines, in the sublingual glands of the chloralose-anaesthetized rat in response to stimulation of the parasympathetic innervation was enhanced by employing an intermittent pattern of nerve stimulation. 20 Hz in bursts delivered for 1 second every 10th second over a period of 3 hours increased the activity 1000-fold, whereas a frequency of 2 Hz delivered continuously, and thus giving rise to the same total number of impulses as the burst stimulation, increased the enzyme activity only 50-fold. Already 2 Hz in bursts caused the ornithine decarboxylase activity to increase. A parasympathetic non-adrenergic, non-cholinergic regulation of ornithine decarboxylase activity was shown in response to the two modes of stimulation. The increase to 2 and 20 Hz in bursts was 2- and 80-fold, respectively, whereas it was 29-fold to 2 Hz continuously. Increases in the concentration of the polyamine putrescine in response to burst stimulation of the parasympathetic nerve were found both in the absence and in the presence of atropine. The ornithine decarboxylase activity of the submaxillary gland was not affected by the parasympathetic stimulation. Stimulation of the sympathetic innervation was more effective in both types of glands, as to increases in the ornithine decarboxylase activity, when employing the continuous mode. In cultured tissue of the sublingual glands which, in vivo, had been subjected to parasympathetic stimulation in bursts (20 Hz), the syntheses of DNA and protein were increased as judged by the incorporation of radio-labelled thymidine and leucine; in the presence of atropine the stimulation resulted only in increased synthesis of protein.