کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
6262397 | 1613796 | 2016 | 11 صفحه PDF | دانلود رایگان |
- Approximately 80% of Arc POMC neurons express the leptin receptor (POMC/LepR+ cells)
- An elevated degree of co-localization was observed in all brain regions analyzed
- No brain nuclei contained exclusively axonal terminals from POMC/LepRâ neurons
- POMC/LepR+ and POMC/LepRâ cells may contact distinct neurons in some target nuclei.
Neurons that express the prohormone proopiomelanocortin (POMC) in the arcuate hypothalamic nucleus (Arc) are engaged in the regulation of energy balance and glucose homeostasis. Additionally, POMC neurons are considered key first-order cells regulated by leptin. Interestingly, in the Arc, POMC cells that express the leptin receptor (POMC/LepR+ cells) are found side by side with POMC cells not directly responsive to leptin (POMC/LepRâ cells). However, it remains unknown whether these distinct populations innervate different target regions. Therefore, the objective of the present study was to compare the projections of POMC/LepR+ and POMC/LepRâ neurons. Using genetically modified LepR-reporter mice to identify leptin receptor-expressing cells and immunohistochemistry to stain POMC-derived peptides (α-MSH or β-endorphin) we confirmed that approximately 80% of Arc β-endorphin-positive neurons co-expressed leptin receptors. POMC/LepR+ and POMC/LepRâ axons were intermingled in all of their target regions. As revealed by confocal microscopy, we found an elevated degree of co-localization between α-MSH+ axons and the reporter protein (tdTomato) in all brain regions analyzed, with co-localization coefficients ranging from 0.889 to 0.701. Thus, these two populations of POMC neurons seem to project to the same set of brain structures, although one of the two subtypes of POMC axons was sometimes found to be more abundant than the other in distinct subregions of the same nucleus. Therefore, POMC/LepR+ and POMC/LepRâ cells may target separate neuronal populations and consequently activate distinct neuronal circuits within some target nuclei. These findings contribute to unravel the neuronal circuits involved in the regulation of energy balance and glucose homeostasis.
Journal: Brain Research - Volume 1646, 1 September 2016, Pages 366-376