Effects of hypodynamia–hypokinesia on somatosensory evoked potentials in the rat

• Published in: Brain research Vol. 978; no. 1; pp. 162 - 168
• Main Authors: Canu, Marie-Hélène, Langlet, Cécile, Dupont, Erwan, Falempin, Maurice
• Format: Journal Article
• Language: English
• Published: London Elsevier B.V 18-07-2003; Amsterdam Elsevier; New York, NY
• Subjects: Animals; Biological and medical sciences; Central nervous system; Deafferentation; Electric Stimulation; Electrical stimulation; Electrophysiology; Evoked Potentials, Somatosensory - physiology; Fundamental and applied biological sciences. Psychology; hypokinesia; Hypokinesia - physiopathology; Immobilization - adverse effects; Immobilization - physiology; Male; Neural Conduction - physiology; Plasticity; Rats; Rats, Wistar; Reaction Time; Sciatic Nerve - physiology; Somatosensory cortex; Somatosensory Cortex - cytology; Somatosensory Cortex - physiology; Space life sciences; Spinal cord; Spinal Cord - physiology; Vertebrates: nervous system and sense organs; Weightlessness; Somatosensory cortex; Spinal cord; Plasticity; Sensory systems; Electrical stimulation; Weightlessness; Deafferentation; Rat; Electrical stimulus; Rodentia; Central nervous system; Hypokinesia; Electrophysiology; Vertebrata; Mammalia; Somatosensory evoked potential
• ISSN: 0006-8993; 1872-6240
• DOI: 10.1016/S0006-8993(03)02804-X

The aim of this study was to determine if a prolonged period (7 or 14 days) of hypodynamia–hypokinesia (HH) affects the conduction of afferent input and the cortical and spinal responsiveness. Acute recordings of cortical and spinal somatosensory evoked potentials (SEPs) were performed after stimulation of the sciatic nerve in control rats and in rats submitted to 7 or 14 days of HH. HH was obtained by unloading the hindquarter. HH induced some subtle modifications in the SEP characteristics. Latency was increased for the spinal and cortical SEPs after 7 days of HH, and restored after 14 days of HH. A decrease in the amplitude was observed after 14 days of HH for the cortical SEP only. At the end of the experiment, the compound action potential of the sciatic nerve was recorded in vitro in order to evaluate the mean conduction velocity. Results indicate that the nerve velocity was reduced after 14 days of HH. The results also suggest that sensory conduction and/or cortical and spinal excitability are changed after HH.