Electrical stimulation of sympathetic nerves increases the concentration of cyclic AMP in rat pineal gland.

Electrical stimulation of the superior cervical ganglia causes a rapid increase in the concentration of cyclic AMP in the pineal gland of rats. This effect is dependent upon the frequency, voltage, and duration of the stimulus and is markedly potentiated by pretreating the animals with desmethylimipramine. The increase in cyclic AMP is blocked by prior treatment of the rats with reserpine, bretylium, or propanolol but not with phentolamine. These results provide direct evidence that electrical stimulation of sympathetic nerves increases cyclic AMP in a target organ through the release of norepinephrine from presynaptic terminals acting on postsynaptic beta-adrenergic receptors.