title: Preferential expression of IGF-I in small DRG neurons and down-regulation following injury.
abstract: In this study, we examined the expression of insulin-like growth factor I (IGF-I) and its receptor (IGF-IR) in dorsal root ganglia (DRG) neurons in two rodent models of nerve injury: sciatic nerve axotomy and streptozotocin-induced (STZ) painful diabetic neuropathy. We demonstrate that IGF-I and its receptor are preferentially expressed in small (< 25 microm diameter) DRG neurons. There is a significant down-regulation in the expression of IGF-I and IGF-IR in the small DRG neurons of STZ rats by 59% and 71%, respectively. A parallel reduction in expression is shown in axotomized < 25 microm diameter DRG neurons for IGF-I (47%) but not for IGF-IR. The loss of IGF-I support to a population of predominantly nociceptive neurons may contribute to neuropathic pain observed in these models.
mesh_terms: D000344:Afferent Pathways / Q000378:metabolism* / Q000503:physiopathology; D000818:Animals; D019771:Axotomy; D048429:Cell Size / Q000502:physiology; D003921:Diabetes Mellitus, Experimental / Q000150:complications / Q000503:physiopathology; D003929:Diabetic Neuropathies / Q000378:metabolism / Q000503:physiopathology; D004195:Disease Models, Animal; D015536:Down-Regulation / Q000502:physiology*; D005727:Ganglia, Spinal / Q000378:metabolism* / Q000503:physiopathology; D007150:Immunohistochemistry; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008297:Male; D009410:Nerve Degeneration / Q000378:metabolism / Q000503:physiopathology; D036421:Nerve Fibers, Unmyelinated / Q000378:metabolism*; D009437:Neuralgia / Q000378:metabolism* / Q000503:physiopathology; D009619:Nociceptors / Q000378:metabolism*; D010523:Peripheral Nervous System Diseases / Q000378:metabolism* / Q000503:physiopathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017526:Receptor, IGF Type 1 / Q000378:metabolism; D012584:Sciatic Nerve / Q000293:injuries / Q000378:metabolism / Q000601:surgery
chemical_list: D007334:Insulin-Like Growth Factor I; D017526:Receptor, IGF Type 1