It was previously shown [NeuroReport, 3 (1992) 829-832] that unilateral labyrinthectomy (UL) induces Fos expression in several brainstem regions, including the β subnucleus of the inferior olive. Using isotopic 33P in situ hybridization, the present results demonstrate significant changes in oligonucleotide-probed mRNA levels for corticotropin-releasing factor (CRF) in the rat inferior olivary nucleus 4 days following unilateral labyrinthectomy (UL). In the medulla of normal animals there was strong CRF mRNA labeling in the inferior olivary nucleus, and weaker labeling in the vestibular nuclei and prepositus hypoglossi. Following unilateral labyrinthectomy, the contralateral olivary β subnucleus showed a significant increase in CRF message, similar to the contralateral Fos labeling observed after hemilabyrinthectomy [NeuroReport, 3 (1992) 829-832]. In addition, the contralateral A and B subnuclei (IOA/B) of the inferior olive showed a strong increase in CRF labeling, while the ipsilateral dorsal cap of Kooy (IOK) showed a decrease. This novel bidirectional alteration in CRF message in different subdivisions of the same nuclear group indicates the existence of both up and down regulatory mechanisms controlling CRF peptide expression, and reflects the dynamic neurochemical alterations occurring during vestibular compensation.
Bibliographical noteFunding Information:
This work was supported by a graduate student researcher program fellowship NASA /NGT-50563 to G.D.K., and by NIH Grants NS31318, DC01086, DC00110, and DE06682.
- Climbing fiber
- Corticotropin-releasing factor
- Vestibular compensation
- Vestibular nuclei