Y.K. and S-X.W. contributed equally to this work.
Paucity of enkephalin production in neostriatal striosomal neurons: analysis with preproenkephalin–green fluorescent protein transgenic mice
Article first published online: 6 NOV 2008
© The Authors (2008). Journal Compilation © Federation of European Neuroscience Societies and Blackwell Publishing Ltd
European Journal of Neuroscience
Volume 28, Issue 10, pages 2053–2064, November 2008
How to Cite
Koshimizu, Y., Wu, S.-X., Unzai, T., Hioki, H., Sonomura, T., Nakamura, K. C., Fujiyama, F. and Kaneko, T. (2008), Paucity of enkephalin production in neostriatal striosomal neurons: analysis with preproenkephalin–green fluorescent protein transgenic mice. European Journal of Neuroscience, 28: 2053–2064. doi: 10.1111/j.1460-9568.2008.06502.x
- Issue published online: 12 NOV 2008
- Article first published online: 6 NOV 2008
- Received 21 May 2008, revised 9 September 2008, accepted 11 September 2008
- mu-opioid receptor;
Whether or not the striosome compartment of the neostriatum contained preproenkephalin (PPE)-expressing neurons remained unresolved. To address this question by developing a sensitive detection method, we generated transgenic mice expressing enhanced green fluorescent protein (GFP) under the specific transcriptional control of the PPE gene. Eight transgenic lines were established, and three of them showed GFP expression which was distributed in agreement with the reported localization of PPE mRNA in the central nervous system. Furthermore, in the matrix compartment of the neostriatum of the three lines, intense GFP immunoreactivity was densely distributed in the neuronal cell bodies and neuropil, and matrix neurons displayed > 94% co-localization for GFP and PPE immunoreactivities. In sharp contrast, GFP immunoreactivity was very weak in the striosome compartment, which was characterized by intense immunoreactivity for mu-opioid receptors (MOR). Although neostriatal neurons were divided into GFP-immunopositive and -negative groups in both the striosome and matrix compartments, GFP immunoreactivity of cell bodies was much weaker (∼1/5) in GFP-positive striosomal neurons than in GFP-positive matrix neurons. A similar reciprocal organization of PPE and MOR expression was also suggested in the ventral striatum, because GFP immunoreactivity was weaker in intensely MOR-immunopositive regions than in the surrounding MOR-negative regions. As PPE-derived peptides are endogenous ligands for MOR in the neostriatum and few axon collaterals of matrix neurons enter the striosome compartment, the present results raised the question of the target of those peptides produced abundantly by matrix neurons.