Electric field stimulation releases norepinephrine and cyclic GMP from the rat pineal gland.

Electrical field stimulation caused the release of preloaded ³H-norepinephrine and of cyclic GMP from the rat pineal gland. Increased release of catecholamines and of cyclic nucleotide occurred at low frequency and current, and was largely dependent on the presence of intact nerve endings and extracellular calcium. Presynaptic synthesis and release of cyclic GMP appears to accompany the exocytotic release of neurotransmitter.