title: Reciprocal synaptic relationships between angiotensin II-containing neurons and enkephalinergic neurons in the rat area postrema.
abstract: A preembedding double immunostaining technique was used to study synaptic relationships between angiotensin-II-like immunoreactive and enkephalin-like immunoreactive neurons in the rat area postrema. The angiotensin-II-like immunoreactive neurons were detected by silver-gold intensification of the DAB reaction results while the enkephalin-like immunoreactive neurons were detected by simple ABC-DAB reaction. The synaptic relationships were reciprocal between the two neurons. Most of the synapses found between these two neurons were the presynaptic enkephalin-like immunoreactive axon terminals that made synapses on the angiotensin-II-like immunoreactive perikarya and dendrites. Both the axo-somatic and axo-dendritic synapses were symmetrical. However, although angiotensin-II-like immunoreactive axon terminals also made synapses on enkephalin-like perikarya and dendrites, the axo-somatic synapses were symmetrical, while the axo-dendritic synapses were asymmetrical. The present results confirm the presence of angiotensin-II-like immunoreactive neurons in the area postrema and suggest that these angiotensinergic neurons in the area postrema may play a role in the regulation of blood pressure via coordinated synaptic interactions with enkephalinergic neurons.
authors.affiliation: Department of Anatomy, Showa University School of Medicine, Tokyo 142-8555, Japan.
authors.forename: J L
authors.initials: JL
authors.lastname: Guan
authors.forename: Q P
authors.initials: QP
authors.lastname: Wang
authors.forename: S
authors.initials: S
authors.lastname: Lu
authors.forename: S
authors.initials: S
authors.lastname: Shioda
mesh_terms: D000804:Angiotensin II / Q000378:metabolism*; D000818:Animals; D002628:Chemoreceptor Cells / Q000378:metabolism / Q000648:ultrastructure*; D004745:Enkephalins / Q000378:metabolism*; D020546:Fourth Ventricle / Q000378:metabolism / Q000648:ultrastructure*; D007150:Immunohistochemistry; D008297:Male; D008526:Medulla Oblongata / Q000378:metabolism / Q000648:ultrastructure*; D008854:Microscopy, Electron; D009434:Neural Pathways / Q000378:metabolism / Q000648:ultrastructure; D009474:Neurons / Q000378:metabolism / Q000648:ultrastructure*; D017729:Presynaptic Terminals / Q000378:metabolism / Q000648:ultrastructure; D051381:Rats; D017208:Rats, Wistar; D013569:Synapses / Q000378:metabolism / Q000648:ultrastructure*
chemical_list: D004745:Enkephalins; D000804:Angiotensin II