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Enhanced heat shock protein 25 immunoreactivity in cranial nerve motoneurons and their related fiber tracts in rats prenatally‐exposed to X ‐irradiation
Author(s) -
Sawada Kazuhiko,
Saito Shigeyoshi,
HoriuchiHirose Miwa,
Murase Kenya
Publication year - 2014
Publication title -
congenital anomalies
Language(s) - English
Resource type - Journals
eISSN - 1741-4520
pISSN - 0914-3505
DOI - 10.1111/cga.12028
Subject(s) - immunostaining , pons , anatomy , brainstem , medulla oblongata , biology , dorsal motor nucleus , area postrema , nucleus , pathology , solitary tract , hypoglossal nucleus , parabrachial nucleus , vagus nerve , central nervous system , medicine , immunohistochemistry , endocrinology , neuroscience , stimulation
Alterations in histoarchitecture of the brainstem were examined immunohistochemically in 4‐week‐old rats with a single whole body X ‐irradiation at a dose of 0.5, 1.0, or 1.5 G y on embryonic day ( ED ) 15 using anti‐heat shock protein 25 ( HSP25 ). HSP25 immunostaining was seen in the neuronal perikarya of cranial nerve motoneurons, that is, the motor and mesencephalic nuclei of the trigeminal nerve, facial nucleus, abducens nucleus and accessory facial nucleus in the pons, and the ambiguous nucleus, dorsal nucleus of vagus nerve and hypoglossus nucleus in the medulla oblongata of intact controls. In 0.5 to 1.5 G y‐irradiated rats, HSP25 immunostaining in those neurons was more intense than in controls, while the most intense immunostaining was marked in 1.5 G y‐irradiated rats. HSP25 immunostaining was also apparent in the spinal tract of the trigeminal nerve and facial nerve tracts in 0.5 to 1.5 G y‐irradiated rats, but was faint in controls. Interestingly, HSP25 immunostaining was aberrantly enhanced in dendritic arbors in the magnocellular region of medial vestibular nucleus of 0.5–1.5 G y‐irradiated rats. Those arbors were identified as excitatory secondary vestibulo‐ocular neurons by double immunofluorescence for HSP25 and SMI ‐32. The results suggest an increase of HSP25 expression in cranial nerve motoneurons and their related fiber tracts from prenatal exposure to ionizing irradiation. This may be an adaptive response to chronic hypoxia due to malformed brain arteries caused by prenatal ionizing irradiation.