6533b82ffe1ef96bd12952bf

RESEARCH PRODUCT

Effects of electrical stimulation of the superior cervical ganglia on the number of ?synaptic? ribbons and the activity of melatonin-forming enzymes in the rat pineal gland

Jörg H. StehleLutz VollrathStefan ReussA. SeidelHannsjörg SchröderWerner Concemius

subject

Acetylserotonin O-MethyltransferaseMaleNervous systemendocrine systemEmbryologySuperior cervical ganglionmedicine.medical_specialtyArylamine N-AcetyltransferaseStimulationBiologyPineal GlandMelatoninPineal glandInternal medicinemedicineAnimalsMelatoninGanglia SympatheticRats Inbred StrainsCell BiologyMetabolismElectric StimulationRatsMicroscopy Electronmedicine.anatomical_structureEndocrinologySynapsesCervical gangliaSerotoninAnatomyDevelopmental Biologymedicine.drug

description

Melatonin metabolism in the mammalian pineal gland is under the clear influence of sympathetic fibers originating in the superior cervical ganglia (SCG). Previous studies suggested that pineal "synaptic" ribbons (SR) as well are regulated by the gland's sympathetic innervation. To gain more insight into the mechanisms involved, we examined the effects of sympathetic stimulation on SR number and on the activity of melatonin forming enzymes, serotonin N-acetyltransferase (NAT) and hydroxyindole-O-methyltransferase (HIOMT). The SCG in adult male rats were stimulated electrically during daytime for either 15 or 120 min. Immediately following stimulation, the glands were removed and processed for electron microscopy and for the determination of NAT and HIOMT activities. No differences in pineal SR number, size or location were found in rats stimulated with either parameters when compared with sham-stimulated or control animals. While the activity of HIOMT remained unchanged, the activity of NAT was also unaltered following 15 min of stimulation, but was augmented approximately three-fold in animals stimulated for 120 min. It is concluded that if SR in the rat pineal gland are under sympathetic control, the regulation is different from that involved in melatonin formation.

https://doi.org/10.1007/bf00305060