Horvath TL, Sarman B, GarcÃa-CÃ¡ceres C, Enriori PJ, Sotonyi P, Shanabrough M, Borok E, Argente J, Chowen JA, Perez-Tilve D, Pfluger PT, BrÃ¶nneke HS, Levin BE, Diano S, Cowley MA, TschÃ¶p MH
Synaptic input organization of the melanocortin system predicts diet-induced hypothalamic reactive gliosis and obesity.
Proc Natl Acad Sci U S A. 2010 Aug 17;107(33):14875-80
Authors: Horvath TL, Sarman B, GarcÃa-CÃ¡ceres C, Enriori PJ, Sotonyi P, Shanabrough M, Borok E, Argente J, Chowen JA, Perez-Tilve D, Pfluger PT, BrÃ¶nneke HS, Levin BE, Diano S, Cowley MA, TschÃ¶p MH
The neuronal circuits involved in the regulation of feeding behavior and energy expenditure are soft-wired, reflecting the relative activity of the postsynaptic neuronal system, including the anorexigenic proopiomelanocortin (POMC)-expressing cells of the arcuate nucleus. We analyzed the synaptic input organization of the melanocortin system in lean rats that were vulnerable (DIO) or resistant (DR) to diet-induced obesity. We found a distinct difference in the quantitative and qualitative synaptology of POMC cells between DIO and DR animals, with a significantly greater number of inhibitory inputs in the POMC neurons in DIO rats compared with DR rats. When exposed to a high-fat diet (HFD), the POMC cells of DIO animals lost synapses, whereas those of DR rats recruited connections. In both DIO rats and mice, the HFD-triggered loss of synapses on POMC neurons was associated with increased glial ensheathment of the POMC perikarya. The altered synaptic organization of HFD-fed animals promoted increased POMC tone and a decrease in the stimulatory connections onto the neighboring neuropeptide Y (NPY) cells. Exposure to HFD was associated with reactive gliosis, and this affected the structure of the blood-brain barrier such that the POMC and NPY cell bodies and dendrites became less accessible to blood vessels. Taken together, these data suggest that consumption of an HFD has a major impact on the cytoarchitecture of the arcuate nucleus in vulnerable subjects, with changes that might be irreversible due to reactive gliosis.
PMID: 20679202 [PubMed - in process]