Postnatal expression of TrkB receptor in rat vestibular nuclear neurons responsive to horizontal and vertical linear accelerations.
We examined the maturation expression profile of tyrosine kinase B (TrkB) receptor in rat vestibular nuclear neurons that were activated by sinusoidal linear acceleration along the horizontal or vertical axis. The otolithic origin of Fos expression in these neurons was confirmed with labyrinthectomized controls and normal controls, which showed only sporadically scattered Fos-labeled neurons in the vestibular nucleus. In P4-6 test rats, no Fos-labeled neurons were found in the vestibular nucleus, but the medial and spinal vestibular neurons showed weak immunoreactivity for TrkB. The intensity of TrkB immunoreactivity in vestibular nuclear neurons progressively increased in the second postnatal week but remained low in adults. From P7 onward, TrkB-expressing neurons responded to horizontal or vertical otolithic stimulation with Fos expression. The number of Fos-labeled vestibular nuclear neurons expressing TrkB increased with age, from 13-43% in P7 rats to 85-90% in adult rats. Our results therefore suggest that TrkB/neurotrophin signaling plays a dominant role in modulating vestibular nuclear neurons for the coding of gravity-related horizontal head movements and for the regulation of vestibular-related behavior during postnatal development.
Department of Physiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, People's Republic of China.
Chun-Wai
CW
Ma
Fu-Xing
FX
Zhang
Chun-Hong
CH
Lai
Suk-King
SK
Lai
Ken Kin-Lam
KK
Yung
Daisy Kwok-Yan
DK
Shum
Ying-Shing
YS
Chan
D000054:Acceleration; D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D005260:Female; D018466:Gravity Sensing / Q000502:physiology*; D019416:Head Movements / Q000502:physiology*; D008297:Male; D009474:Neurons / Q000378:metabolism*; D010037:Otolithic Membrane / Q000254:growth & development / Q000294:innervation* / Q000502:physiology; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D020813:Receptor, trkB / Q000378:metabolism*; D014726:Vestibular Nuclei / Q000166:cytology / Q000254:growth & development / Q000378:metabolism*; D014722:Vestibule, Labyrinth / Q000294:innervation / Q000502:physiology / Q000601:surgery
D016760:Proto-Oncogene Proteins c-fos; D020813:Receptor, trkB