[Experimental study on promotion of somato-visceral heterogenic reinnervation with nerve growth factor in rat phrenic-to-vagus anastomosis model].
OBJECTIVE
To investigate the influence of nerve growth factor (NGF) on neuronal regeneration of somato-visceral heterogenic reinnervation using a rat phrenic-to-vagus anastomosis model.


METHODS
Forty male SD rats, aging 3 months and weighing 200 g, were selected and randomly divided into 3 groups. In group A (n = 10, control group), phrenic and vagus nerves were exposed and no neurography was performed. In group B (n = 15) and group C (n = 15), both nerves were transected and proximal stump of phrenic nerves were microsurgically anastomosed to the distal stump of vagus nerves. Postoperatively, group C was intraperitoneally injected with NGF (20 microg/kg x d), while groups A and B were given matching saline solution. Twelve weeks later, cardiac function was examined under electrical stimulation of the regenerated nerve. Light and electron microscopies were used to examine the heterogenic regenerated nerve, and the passing rate of axon and thickness of myelin sheath were calculated.


RESULTS
Under electrical never stimulation in groups A, B, and C, the decreases of blood pressure were (20.12 +/- 2.57), (10.63 +/- 2.44), and (14.18 +/- 2.93) mmHg (1 mmHg = 0.133 kPa), respectively; and the decreases of heart rate were (66.77 +/- 9.96), (33.44 +/- 11.82), and (43.27 +/- 11.02)/minutes, respectively. In group B, the decrease amplitudes of blood pressure and heart rate were 52.83% and 50.08% of group A, respectively. Blood pressure and heart rate in group C also decreased dramatically; the decrease amplitudes of blood pressure and heart rate in group C were 70.48% and 64.80% of group A. There were significant differences in the decrease amplitudes of blood pressure and heart rate (P < 0.05) between group B and group C. Morphological observation showed that heterogenic nerve fibers had the structure of matured myelin sheath and their axons could regenerate into the vagus nerve. In group B and group C, the passing rates of axon were 66.83% +/- 4.46% and 81.63% +/- 3.56%, respectively; and the thicknesses of myelin sheath were (0.25 +/- 0.10) microm and (0.46 +/- 0.08) microm, respectively; showing significant differences (P < 0.05) between group B and group C.


CONCLUSIONS
Heterogenic nerve is primarily a somatic motor nerve; NGF can promote the axons of heterogenic nerve to regenerate into the parasympathetic nerve.
Du
Shouchao
S
Department of Orthopedics, Tongji Hospital, Tongji University, Shanghai 200065, PR China.
Zhang
Shimin
S
Ye
Xiaosheng
X
Ye
Hongfeng
H
D000818:Animals; D008297:Male; D020932:Nerve Growth Factor / Q000494:pharmacology*; D009416:Nerve Regeneration / Q000187:drug effects* / Q000502:physiology; D010791:Phrenic Nerve / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D014630:Vagus Nerve / Q000502:physiology
D020932:Nerve Growth Factor