Transmitters and modulators in the superior cervical ganglion of the rat

Several transmitters and modulators have been found to exist in the superior cervical ganglion of the rat. It has been shown that noradrenaline is present in the principal neurons and dopamine is the main catecholamine in the small intensely fluorescent cells. 5-hydroxytryptamine and histamine have been investigated immunohistochemically and found to be present only in the small intensely fluorescent cells of an adult rat, in the same cells which are also immunoreactive to tyrosine hydroxylase. On the other hand, enkephalins which were studied using highly specific antibodies against methionine-enkephalin-arginine-phenylalanine and methionine-enkephalin-arginine-glycine-leucine were found in the principal neurons and nerve fibres. Ligation studies showed that enkephalins in the superior cervical ganglion of the rat are both of intrinsic and extrinsic origin. It is evident that the transmission in the sympathetic ganglion is complex. The possible function of the transmitter and modulator candidates is discussed.