Expression of acidic FGF mRNA in rat auditory brainstem during postnatal maturation
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1Department of Surgery, UCSD School of Medicine, La Jolla 92093-0666, USA.
Abstract:
In situ hybridization was used to investigate the mRNA distribution of acidic and basic fibroblast growth factor (aFGF and bFGF) in the auditory brainstem of neonatal and adult rats. bFGF mRNA was not detected at any age. In adult rats, aFGF mRNA was strongly expressed in the principal neurons of the anteroventral and posteroventral cochlear nuclei, but not in the octopus cells. In the dorsal cochlear nucleus, aFGF mRNA was seen only in scattered smaller vertical cells. aFGF was strongly expressed in the nucleus of the trapezoid body and in all periolivary cell groups, but not in the medial and lateral olivary nuclei. No expression was observed in the lemniscal nuclei or in the central nucleus of the inferior colliculus, but large neurons in the external zone of the colliculus were labeled. Developmentally, low levels of aFGF expression appeared in the cochlear nuclei and olivary nuclei between P0 and P6. This expression increased rapidly during the onset of hearing, between P10 and P14, and reached adult level by P14-P17. Labeling in collicular neurons appeared slightly later. The results suggest that the appearance of strong aFGF mRNA expression is related to the onset of function.
Insights
Acidic fibroblast growth factor (aFGF) mRNA is present in the adult rat auditory brainstem, particularly in cochlear nuclei and olivary nuclei. Its expression increases significantly with the onset of hearing, suggesting a functional role.
Area of Science:
- Neuroscience
- Developmental Biology
- Molecular Biology
Background:
- Fibroblast growth factors (FGFs) are crucial signaling molecules involved in cell growth, differentiation, and tissue repair.
- Acidic fibroblast growth factor (aFGF) and basic fibroblast growth factor (bFGF) are members of the FGF family with distinct roles.
- The auditory brainstem processes complex auditory information and undergoes significant developmental changes.
Purpose of the Study:
- To map the distribution of acidic fibroblast growth factor (aFGF) and basic fibroblast growth factor (bFGF) mRNA in the auditory brainstem of rats at different developmental stages.
- To investigate the relationship between aFGF expression and the onset of hearing.
Main Methods:
- In situ hybridization was employed to detect and localize aFGF and bFGF mRNA.
- The study examined neonatal (P0-P6) and adult rats, as well as specific developmental time points (P10-P17).
Main Results:
- bFGF mRNA was undetectable in the auditory brainstem at any age.
- In adult rats, aFGF mRNA was highly expressed in principal neurons of the cochlear nuclei and in the nucleus of the trapezoid body and periolivary cell groups.
- aFGF expression was low in neonatal rats but increased significantly between P10 and P14, coinciding with the onset of hearing, and reached adult levels by P14-P17.
Conclusions:
- The study demonstrates a specific expression pattern for aFGF in the adult auditory brainstem, with notable absence of bFGF.
- The developmental upregulation of aFGF mRNA correlates with the onset of auditory function, suggesting a role in auditory system maturation and processing.