The reduction of proprioceptors in the mesencephalic trigeminal tract nucleus after neonatal masseteric nerve transection; effect of brain-derived neurotrophic factor.
The effect of neonatal masseteric nerve transection on primary proprioceptors was examined in the mesencephalic trigeminal tract nucleus (Mes5) of the rat. At 72 h to 21 days after the injury, the number of Mes5 neurons decreased on the side ipsilateral to the transection. The means+/-SD of percentage proportion of ipsilateral/contralateral neurons at 72 h and 21 days were 69.9+/-7.5% and 58.2+/-14.6%, respectively. The application of brain-derived neurotrophic factor to the proximal stump of the masseteric nerve delayed the loss of Mes5 neurons at 72 h after the injury; the mean numbers+/-SD of ipsilateral and contralateral Mes5 neurons in injured animals with BDNF application was 553.6+/-61.9 and 558.4+/-55.3, respectively. Saline application had no effect on the injury-induced loss of Mes5 neurons; i.e., the mean numbers+/-SD of ipsilateral and contralateral Mes5 neurons were 367.3+/-72.5 and 543+/-33.5, respectively. These findings indicate that trigeminal primary proprioceptors are sensitive to the neonatal injury. The survival of proprioceptors during early postnatal period is probably dependent upon brain-derived neurotrophic factor in the trigeminal nervous system.
Ichikawa
H
H
Department of Oral Function and Anatomy, Okayama University Graduate School of Medicine and Dentistry, 2-5-1 Shikata-cho, Okayama 700-8525, Japan. hiroichi@md.okayama-u.ac.jp
Jin
H W
HW
Terayama
S
S
Yamaai
T
T
Matsuo
S
S
Sugimoto
T
T
D000818:Animals; D000831:Animals, Newborn; D019771:Axotomy / Q000379:methods; D019208:Brain-Derived Neurotrophic Factor / Q000008:administration & dosage*; D002452:Cell Count / Q000379:methods; D005260:Female; D007839:Functional Laterality; D008297:Male; D008406:Masseter Muscle / Q000294:innervation*; D009474:Neurons / Q000378:metabolism; D010320:Parvalbumins / Q000378:metabolism; D010523:Peripheral Nervous System Diseases / Q000209:etiology / Q000473:pathology*; D051381:Rats; D013997:Time Factors; D014278:Trigeminal Nuclei / Q000473:pathology / Q000503:physiopathology*
D019208:Brain-Derived Neurotrophic Factor; D010320:Parvalbumins