Plasma membrane calcium ATPase in synaptic terminals of chick Edinger-Westphal neurons

• Published in: Brain research 1996-09, Vol.734 (1-2), p.193-202
• Main Authors: FUJII, J. T, FEI TENG SU, WOODBURY, D. J, KURPAKUS, M, HU, X.-J, POURCHO, R
• Format: Article
• Language: English
• Subjects: Animals; Animals, Newborn; Biochemistry and metabolism; Biological and medical sciences; Brain Stem - cytology; Brain Stem - metabolism; Calcium-Transporting ATPases - metabolism; Cation Transport Proteins; Central nervous system; Chick Embryo; Chickens; Electric Organ - metabolism; Fundamental and applied biological sciences. Psychology; Ganglia, Parasympathetic - metabolism; Neurons - metabolism; Plasma Membrane Calcium-Transporting ATPases; Presynaptic Terminals - metabolism; Presynaptic Terminals - ultrastructure; Substance P - metabolism; Synaptic Vesicles - metabolism; Synaptic Vesicles - ultrastructure; Tissue Distribution; Torpedo - metabolism; Vertebrates: nervous system and sense organs
• ISSN: 0006-8993; 1872-6240
• DOI: 10.1016/S0006-8993(96)00638-5

The plasma membrane calcium ATPase pump (PMCA) is one of two major mechanisms known to be involved in extruding calcium from cells. The monoclonal antibody 5F10 was used to examine the distribution of PMCA in chick Edinger-Westphal neurons, a population of cholinergic preganglionic neurons whose cells bodies reside in the Edinger-Westphal nucleus in the brainstem and whose axons form synaptic terminals on parasympathetic neurons in the ciliary ganglion. Definitive PMCA immunoreactivity was undetectable in Edinger-Westphal cell bodies in the brainstem. In contrast, immunoreactivity for PMCA was robust in ciliary ganglia and resembled patterns of immunoreactivity for the synaptic vesicle antigen SV-2, suggesting that PMCA is expressed in Edinger-Westphal synaptic terminals. Moreover, PMCA immunoreactivity co-localized with immunoreactivity for enkephalin and substance P, two neuropeptides known to be expressed in Edinger-Westphal synaptic terminals. Fine structure studies revealed that PMCA immunoreactivity is associated with synaptic vesicles rather than the plasma membrane in Edinger-Westphal terminals. In immunodot assays, synaptic vesicles purified from Torpedo electric organ are also immunoreactive for PMCA as well as SV-2. Torpedo vesicles are negative for the sarcoplasmic/ endoplasmic reticulum ATPase, suggesting that the observed PMCA immunoreactivity is not associated with smooth endoplasmic reticulum. Immunoblot analysis confirmed that 5F10 recognizes a protein with the correct molecular mass for PMCA in tissue homogenates of chick cerebellum, chick ciliary ganglia, and Torpedo synaptic vesicles. These findings describe a previously unrecognized location for PMCA in the membranes of cholinergic synaptic vesicles. Relevance to previous data and possible functions are discussed.