Transient increase in insulin-like growth factor I immunoreactivity in rat peripheral nerves exposed to vibrations.
Hind legs of adult rats were exposed to vibrations (81 Hz; amplitude 0.50 mm peak to peak) for 4 h during two consecutive days. The sciatic, tibial and plantar nerves were isolated and processed for immunohistochemical demonstration of IGF-I (insulin-like growth factor I; somatomedin C) immunoreactivity at different time intervals after the vibration exposure. In sham-exposed rats the axons in peripheral nerves showed no or faint IGF-I immunoreactivity while most Schwann cells were negative. Exposure of the hind legs to vibrations induced increased IGF-I immunoreactivity in the Schwann cells, demonstrable at the end of the exposure period and reaching maximal intensity 2-3 days after vibration exposure. Several distended axons similarly showed increased staining. The IGF-I immunoreactivity decreased after 7-10 days to almost the level in the control nerves. The most extensive changes were observed in the plantar nerves. The tibial nerves similarly expressed strongly increased IGF-I immunoreactivity in their Schwann cells. The sciatic nerve showed, however, only slightly to moderately increased staining. Cells in the epineurium of the plantar and, to a limited extent, of the tibial nerves expressed concomitantly increased IGF-I immunoreactivity. We conclude that the transiently increased IGF-I immunoreactivity in peripheral nerves reflects reactive changes caused by vibrations and most prominently expressed by the Schwann cells.
Hansson
H A
HA
Institute of Neurobiology, University of Göteborg, Sweden.
Dahlin
L B
LB
Löwenadler
B
B
Lundborg
G
G
Paleus
S
S
Skottner
A
A
D000818:Animals; D005455:Fluorescent Antibody Technique; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008297:Male; D008856:Microscopy, Fluorescence; D010525:Peripheral Nerves / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012584:Sciatic Nerve / Q000378:metabolism; D013002:Somatomedins / Q000378:metabolism*; D013979:Tibial Nerve / Q000378:metabolism; D014732:Vibration / Q000009:adverse effects*
D013002:Somatomedins; D007334:Insulin-Like Growth Factor I