Expression of GABAergic and glutamatergic phenotypic markers in hypothalamic proopiomelanocortin neurons
Article first published online: 1 OCT 2012
Copyright © 2012 Wiley Periodicals, Inc.
Journal of Comparative Neurology
Volume 520, Issue 17, pages 3863–3876, 1 December 2012
How to Cite
Jarvie, B. C. and Hentges, S. T. (2012), Expression of GABAergic and glutamatergic phenotypic markers in hypothalamic proopiomelanocortin neurons. J. Comp. Neurol., 520: 3863–3876. doi: 10.1002/cne.23127
- Issue published online: 1 OCT 2012
- Article first published online: 1 OCT 2012
- Accepted manuscript online: 23 APR 2012 03:04AM EST
- Manuscript Accepted: 13 APR 2012
- Manuscript Revised: 24 FEB 2012
- Manuscript Received: 20 JAN 2012
- National Institute of Diabetes and Digestive and Kidney Diseases. Grant Number: R01DK0798749
- in situ hybridization
Hypothalamic proopiomelanocortin (POMC) neurons have traditionally been defined by their peptide transmitters, which are important regulators of energy balance and reward. Recent work shows that POMC neurons can also release the amino acid transmitters γ-aminobutyric acid (GABA) and glutamate, although studying GABAergic and glutamatergic populations of POMC neurons has been hindered by the difficulty in reliably identifying amino acid (AA) transmitter phenotypes. In the present study, fluorescent in situ hybridization and immunohistochemistry were used to identify POMC neurons and to detect the presence of mRNA for the transporters responsible for packaging either GABA (vesicular GABA transporter [vGAT]) or glutamate (vesicular glutamate transporter [vGLUT]) into vesicles, as well as the enzymes responsible for GABA synthesis, glutamic acid decarboxylase (GAD)65 and GAD67. Approximately 7% of POMC neurons expressed vGlut2 and the highest percentage of vGlut2-positive POMC cells were located in the rostral arcuate nucleus. Despite the reports of GABA release from POMC neurons, vGat was not detected in POMC neurons, although Gad65 and Gad67 were present in ∼40% of POMC neurons. Approximately half of the vGlut2-expressing POMC cells also expressed Gad65. Markers of neurotransmitter phenotype were better detected by using in situ hybridization techniques rather than transgenic expression of fluorophores under the control of the vGat or Gad67 promoters. It is now clear that the expression of markers of AA phenotype provides a useful means to identify distinct subpopulations of POMC neurons. Additionally, the method described will be useful to explore the possibility that plasticity of AA phenotype is an important aspect of POMC neuron function. J. Comp. Neurol. 520:3863–3876, 2012. © 2012 Wiley Periodicals, Inc.