Concentration of amino acid neurotransmitters in the somatosensory cortex of the rat after surgical or functional deafferentation
Hindlimb unloading is considered as a model of functional deafferentation, since in this situation the tactile information from the paw and the proprioceptive input from the limb are dramatically reduced. Unloading induces a shrinkage of the cortical representation of the affected body part associated to a reorganization of topographic maps and to an expansion of receptive fields. Previous studies have suggested that cortical plasticity was the result of a change in the balance of excitation and inhibition in the cortex. The aim of the present study was thus to determine whether deafferentation of the hindlimb representation in the somatosensory cortex, by 14 days of unloading or by surgical means (selective dorsal rhizotomy during 17 days), can change the concentration in various amino acid neurotransmitters in the deprived cortex. The present findings indicate that both types of deafferentation result in a decrease in inhibitory amino acids (GABA, taurine) without significant changes in the main excitatory amino acid (glutamate). In conclusion, the present results support the idea that cortical changes are more likely due to a release from inhibition than to an increased excitation.
KeywordsHindlimb unloading Rhizotomy Cortical plasticity Glutamate GABA
- De-Doncker L, Kasri M, Picquet F, Falempin M (2005) Physiologically adaptive changes of the L5 afferent neurogram and of the rat soleus EMG activity during 14 days of hindlimb unloading and recovery. J Exp Biol 208(Pt 24):4585–4592Google Scholar
- Fletcher EJ, Beart PM, Lodge D (1990) Involvement of glycine in excitatory neurotransmission. In: Ottersen OP, Storm-Mathisen J (Eds) Glycine neurotransmission. Wiley, New York, pp 193–218Google Scholar
- Leonard BE (2003) Basic aspects of neurotransmitter function. In: Leonard BE (eds) Fundamentals of psychopharmacology, 3rd edn. Wiley, Chichester, pp 15–78Google Scholar