title: Quantitative analysis of survival of hypoglossal neurons in neonatally nerve-injured rats: Correlation with milk intake.
abstract: BACKGROUND
  Tongue movement innervated by the hypoglossal (XII) nerve is essential for the survival of neonatal rats. The pups with bilateral XII nerve resection failed to suckle milk and did not survive, and the pups with unilateral XII nerve resection showed disturbed suckling capability and lower survival rates. The present study was performed to investigate the relation between neuronal population and milk intake of developing rats that had received various degrees of crush injuries to the unilateral XII nerve during the neonatal period.
  
  
  METHODS
  The right XII nerve of postnatal day 1 (P1) pups was crushed and milk intake was estimated at 3 days and 6 days after the nerve injury. As nerve injury at the neonatal stage results in death of axotomized neurons, varying degrees of crushing was estimated by the number of survived motor neurons.
  
  
  RESULTS
  In nerve-crushed rats, the populations of XII motor neurons and amounts of milk intake were reduced in a varied manner. Statistically significant positive correlations were observed between increasing XII neuron survival and increasing milk intake at 3 (r=0.62) and 6 (r=0.71) days after the nerve injury.
  
  
  CONCLUSIONS
  The results indicate that there is a strong relationship between the number of XII motor neurons and the amount of milk intake in neonatally XII nerve-injured rats.
authors.affiliation: Department of Anatomy, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, Nagano 390-8621, Japan. Electronic address: nanae@shinshu-u.ac.jp.
authors.forename: Nanae
authors.initials: N
authors.lastname: Fukushima
authors.affiliation: Department of Anatomy, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, Nagano 390-8621, Japan.
authors.forename: Kumiko
authors.initials: K
authors.lastname: Yokouchi
authors.affiliation: Department of Anatomy, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, Nagano 390-8621, Japan.
authors.forename: Kyutaro
authors.initials: K
authors.lastname: Kawagishi
authors.affiliation: Department of Anatomy, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, Nagano 390-8621, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Kakegawa
authors.affiliation: Department of Anatomy, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, Nagano 390-8621, Japan.
authors.forename: Norimi
authors.initials: N
authors.lastname: Sumitomo
authors.affiliation: Department of Anatomy, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, Nagano 390-8621, Japan.
authors.forename: Mika
authors.initials: M
authors.lastname: Karasawa
authors.affiliation: Department of Anatomy, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, Nagano 390-8621, Japan.
authors.forename: Tetsuji
authors.initials: T
authors.lastname: Moriizumi
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D000833:Animals, Suckling; D005260:Female; D061228:Hypoglossal Nerve Injuries / Q000503:physiopathology*; D008892:Milk; D009046:Motor Neurons / Q000502:physiology; D010784:Photomicrography; D011247:Pregnancy; D051381:Rats; D017208:Rats, Wistar; D013391:Sucking Behavior / Q000502:physiology*
keywords: Crush injury; Hypoglossal nerve; Hypoglossal nucleus; Neonatal rats; Suckling