title: Role of IGF-1 in cortical plasticity and functional deficit induced by sensorimotor restriction.
abstract: In the adult rat, sensorimotor restriction by hindlimb unloading (HU) is known to induce impairments in motor behavior as well as a disorganization of somatosensory cortex (shrinkage of the cortical representation of the hindpaw, enlargement of the cutaneous receptive fields, decreased cutaneous sensibility threshold). Recently, our team has demonstrated that IGF-1 level was decreased in the somatosensory cortex of rats submitted to a 14-day period of HU. To determine whether IGF-1 is involved in these plastic mechanisms, a chronic cortical infusion of this substance was performed by means of osmotic minipump. When administered in control rats, IGF-1 affects the size of receptive fields and the cutaneous threshold, but has no effect on the somatotopic map. In addition, when injected during the whole HU period, IGF-1 is interestingly implied in cortical changes due to hypoactivity: the shrinkage of somatotopic representation of hindlimb is prevented, whereas the enlargement of receptive fields is reduced. IGF-1 has no effect on the increase in neuronal response to peripheral stimulation. We also explored the functional consequences of IGF-1 level restoration on tactile sensory discrimination. In HU rats, the percentage of paw withdrawal after a light tactile stimulation was decreased, whereas it was similar to control level in HU-IGF-1 rats. Taken together, the data clearly indicate that IGF-1 plays a key-role in cortical plastic mechanisms and in behavioral alterations induced by a decrease in sensorimotor activity.
authors.affiliation: Laboratoire « Activité Physique, Muscle et Santé », EA 4488, IFR 114, Université Lille 1, Sciences et Technologies, F-59650 Villeneuve d'Ascq, France; Unité de Recherche Pluridisciplinaire Sport, Santé, Société (URePSSS), Université Lille Nord de France, F-59000 Lille, France. Electronic address: julien.mysoet@univ-lille1.fr.
authors.forename: Julien
authors.initials: J
authors.lastname: Mysoet
authors.affiliation: Laboratoire « Activité Physique, Muscle et Santé », EA 4488, IFR 114, Université Lille 1, Sciences et Technologies, F-59650 Villeneuve d'Ascq, France; Unité de Recherche Pluridisciplinaire Sport, Santé, Société (URePSSS), Université Lille Nord de France, F-59000 Lille, France. Electronic address: erwan.dupont@univ-lille1.fr.
authors.forename: Erwan
authors.initials: E
authors.lastname: Dupont
authors.affiliation: Laboratoire « Activité Physique, Muscle et Santé », EA 4488, IFR 114, Université Lille 1, Sciences et Technologies, F-59650 Villeneuve d'Ascq, France; Unité de Recherche Pluridisciplinaire Sport, Santé, Société (URePSSS), Université Lille Nord de France, F-59000 Lille, France. Electronic address: bruno.bastide@univ-lille1.fr.
authors.forename: Bruno
authors.initials: B
authors.lastname: Bastide
authors.affiliation: Laboratoire « Activité Physique, Muscle et Santé », EA 4488, IFR 114, Université Lille 1, Sciences et Technologies, F-59650 Villeneuve d'Ascq, France; Unité de Recherche Pluridisciplinaire Sport, Santé, Société (URePSSS), Université Lille Nord de France, F-59000 Lille, France. Electronic address: marie-helene.canu@univ-lille1.fr.
authors.forename: Marie-Hélène
authors.initials: MH
authors.lastname: Canu
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects / Q000502:physiology*; D004192:Discrimination, Psychological / Q000187:drug effects / Q000502:physiology; D019417:Hindlimb Suspension / Q000502:physiology; D007334:Insulin-Like Growth Factor I / Q000008:administration & dosage / Q000494:pharmacology / Q000502:physiology*; D008297:Male; D009473:Neuronal Plasticity / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D012683:Sensory Deprivation / Q000502:physiology*; D012684:Sensory Thresholds / Q000187:drug effects / Q000502:physiology*; D013003:Somatosensory Cortex / Q000378:metabolism / Q000502:physiology* / Q000503:physiopathology; D014110:Touch / Q000187:drug effects / Q000502:physiology*
chemical_list: D007334:Insulin-Like Growth Factor I
keywords: Adult rat; Cortical plasticity; Cutaneous receptive field; Disuse; Electrophysiology; Hindlimb unloading; Somatotopy; Tactile sensation; Von Frey monofilament