[Responses of afferent unit of the caudal nerve of diabetic hyperalgesic rats to sympathetic efferent stimulation].
Responses of afferent unit to sympathetic stimulation (SS), intravenous injection of noradrenaline (NA) and phentolamine in the caudal nerve of diabetic rats were investigated. The results showed that the discharge frequencies of C and Adelta units with spontaneous discharges were increased in diabetic hyperalgesic rats after SS, and these spontaneous discharges were eliminated by adrenergic antagonist. The C (6/21) and Adelta (19/81) units with no spontaneous discharges of diabetic hyperalgesic rat turned from silent state into active state during SS; although SS did not elicit afferent discharges of the C mechanical receptive units (C-M), it elicited afferent discharges of a part of C mechano  heat units (C-MH) and C polymodal units (C-Pol); afferent discharges of some of the Adelta mechanical receptive units (Adelta-M) and Adelta mechano  heat units (Adelta-MH) were also elicited by SS. The latencies of the C and Adelta units responses upon SS were not equal, but no less than 5 s. SS elicited neither afferent discharges from Abeta mechanical receptive units of diabetic hyperalgesic rat, nor receptive units of all types in the control rat. The C(3/8) and Adelta (4/12) units of diabetic hyperalgesic rat were activated by intravenous injection of NA. The present data suggest that NA released from sympathetic nerve terminals excites C and Adelta units of diabetic hypesthesic rat, which may be a peripheral factor in hyperalgesia and paresthesia of diabetic rats.
Liu
J
J
Department of Physiology, School of Medicine, Xian Jiao Tong University, Xian 710061, China. physi-x@xjtu.edu.cn
Wang
K M
KM
Zhang
Q J
QJ
Cao
D Y
DY
D000344:Afferent Pathways; D000818:Animals; D002420:Cauda Equina / Q000503:physiopathology*; D003921:Diabetes Mellitus, Experimental / Q000150:complications / Q000503:physiopathology*; D004525:Efferent Pathways; D005728:Ganglia, Sympathetic / Q000503:physiopathology; D006930:Hyperalgesia / Q000209:etiology / Q000503:physiopathology*; D008297:Male; D009431:Neural Conduction; D009619:Nociceptors / Q000503:physiopathology*; D051381:Rats; D017207:Rats, Sprague-Dawley