Role of IGF-1 in cortical plasticity and functional deficit induced by sensorimotor restriction

Behav Brain Res. 2015 Sep 1;290:117-23. doi: 10.1016/j.bbr.2015.04.055. Epub 2015 May 7.


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.

Keywords: Adult rat; Cortical plasticity; Cutaneous receptive field; Disuse; Electrophysiology; Hindlimb unloading; Somatotopy; Tactile sensation; Von Frey monofilament.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Behavior, Animal / drug effects
  • Behavior, Animal / physiology*
  • Discrimination, Psychological / drug effects
  • Discrimination, Psychological / physiology
  • Hindlimb Suspension / physiology
  • Insulin-Like Growth Factor I / administration & dosage
  • Insulin-Like Growth Factor I / pharmacology
  • Insulin-Like Growth Factor I / physiology*
  • Male
  • Neuronal Plasticity / drug effects
  • Neuronal Plasticity / physiology*
  • Rats
  • Rats, Wistar
  • Sensory Deprivation / physiology*
  • Sensory Thresholds / drug effects
  • Sensory Thresholds / physiology*
  • Somatosensory Cortex / metabolism
  • Somatosensory Cortex / physiology*
  • Somatosensory Cortex / physiopathology
  • Touch / drug effects
  • Touch / physiology*


  • Insulin-Like Growth Factor I