Postsynaptic localization of CB2 cannabinoid receptors in the rat hippocampus.
The expression of CB2 cannabinoid receptors (CB2-Rs) in the brain and their neuronal function has now attracted research interest, since we and others have demonstrated the presence of CB2-Rs in neuronal and glial cells in the brain. In this study, we show the subcellular distribution of CB2-Rs in neuronal, glial, and endothelial cells in the rat hippocampus using immunohistochemical electron microscopy. Brain sections from the hippocampus were immunolabeled for CB2-R, visualized, and analyzed by electron microscopy. We found that in neurons, CB2-R immunoreactivity is present in the cell body as well as in large and medium-sized dendrites. In the soma, the CB2-R labeling is associated with the rough endoplasmic reticulum and Golgi apparatus demonstrating that CB2-Rs are synthesized by hippocampal neurons. CB2-R labeling in dendrites was observed in the cytoplasm and associated with the plasma membrane near the area of synaptic contact with axon terminals indicating a postsynaptic distribution of these receptors. In CB2-R immunoreactive glial and endothelial cells, the labeling was also found to be associated with the plasma membrane. These results provide the first ultrastructural evidence that CB2-Rs are mainly postsynaptic in the rat hippocampus.
Brusco
Alicia
A
Instituto de Biología Celular y Neurociencia, Facultad de Medicina, Universidad de Buenos Aires, Argentina.
Tagliaferro
Patricia
P
Saez
Trinidad
T
Onaivi
Emmanuel S
ES
D000595:Amino Acid Sequence; D000818:Animals; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology; D006624:Hippocampus / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure*; D008297:Male; D016253:Microscopy, Immunoelectron; D008969:Molecular Sequence Data; D051381:Rats; D017207:Rats, Sprague-Dawley; D043885:Receptor, Cannabinoid, CB2 / Q000378:metabolism* / Q000648:ultrastructure*; D013570:Synaptic Membranes / Q000737:chemistry* / Q000648:ultrastructure*
D043885:Receptor, Cannabinoid, CB2