Brn-3a is required for the generation of proprioceptors in the mesencephalic trigeminal tract nucleus.
The distribution of motor and proprioceptive neurons was investigated in the trigeminal nervous system of wild-type and Brn-3a knockout mice at embryonic day 18.5 and postnatal day 0. We found that the trigeminal motor nucleus (Mo5) contained abundant motoneurons in wild-type (mean number +/- SD per section = 128 +/- 22, range = 93-167) and knockout (mean number +/- SD per section = 121 +/- 23, range = 75-158) mice and that the cell size of Mo5 neurons was similar between these mice (wild-type, mean +/- SD = 165 +/- 59 microm2, range = 65-326 microm2; knockout, mean +/- SD = 167 +/- 59 microm2, range = 71-327 microm2). Mo5 neurons were immunoreactive for calcitonin gene-related peptide and such immunoreactive neurons were abundant in both wild-type and mutant mice. In the mesencephalic tract nucleus (Mes5) of wild-type mice, many proprioceptors (mean number +/- SD per section = 56 +/- 19, range = 27-85) that contained parvalbumin immunoreactivity were also observed. In knockout mice, however, Mes5 neurons could not be detected. The area of brainstems which normally contained the Mes5 was devoid of parvalbumin-immunoreactive proprioceptors. The present study suggests that Brn-3a is required for the development of proprioceptors but not motoneurons 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
Qiu
F
F
Xiang
M
M
Sugimoto
T
T
D000818:Animals; D015740:Calcitonin Gene-Related Peptide / Q000235:genetics / Q000378:metabolism; D002452:Cell Count / Q000379:methods; D048429:Cell Size; D004268:DNA-Binding Proteins / Q000172:deficiency / Q000502:physiology*; D004622:Embryo, Mammalian; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D007150:Immunohistochemistry / Q000379:methods; D008636:Mesencephalon / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D009046:Motor Neurons / Q000378:metabolism; D009475:Neurons, Afferent / Q000378:metabolism*; D010320:Parvalbumins / Q000235:genetics / Q000378:metabolism; D050818:Transcription Factor Brn-3; D050819:Transcription Factor Brn-3A; D014157:Transcription Factors / Q000172:deficiency / Q000502:physiology*; D014278:Trigeminal Nuclei / Q000166:cytology* / Q000196:embryology / Q000378:metabolism
D004268:DNA-Binding Proteins; D010320:Parvalbumins; C494189:Pou4f1 protein, mouse; D050818:Transcription Factor Brn-3; D050819:Transcription Factor Brn-3A; D014157:Transcription Factors; D015740:Calcitonin Gene-Related Peptide