Eur J Anat, 4 (2): 83-94 (2000)
c-Fos activation in the superior olivary complex and nuclei of the lateral lemniscus of sound-stimulated rats
Riera-Sala C., Marco-Algarra J., Martinez-Soriano F., Olucha F.E.
Dpto. Ciencias Morfológicas, Facultad de Medicina y Odontologia, Univ. de Valencia, Av. Blasco Ibáñez 17, E-46010 Valencia, Spain
ABSTRACT The pattern of c-fos expression was analyzed along the superior olivary complex and the nuclei of the lateral lemniscus of rats subjected to different types of sound stimuli. A detailed map was obtained by comparing parallel series stained with Giemsa, acetyl cholinesterase histochemistry, and fos immunocytochemistry The experimental groups consisted of rats isolated for 24 hours in a soundproof cage and sound-stimulated rats. Sound-stimulated rats received 5 KHz and a Combination of 4 tones. The superior olivary complex was divided into three levels. The rostral level I contained only the rostral periolivary nucleus. In level II, a core and periolivary nuclei were differentiated. The core was composed of the medial supraolivary nucleus and the lateral supraolivary nucleus and was surrounded by the dorsal periolivary nucleus, the superior periolivary nucleus, the nucleus of the trapezoid body and the medial and lateral divisions of the ventral periolivary nucleus. Caudal to level II, level III, only contained the caudal periolivary nucleus. The medial division of the ventral periolivary nucleus and the rostral periolivary nucleus showed c-fos activation in isolated conditions and were strongly activated following any kind of sound stimulus. The rest of the superior olivary nuclei showed no c-fos activation in isolated rats and a weak but consistently constant activation following sound stimulation. No c-fos activation was obtained in the core of the lateral supraolivary nucleus; however, some labeling occurred in the hilus around the nucleus. The lateral lemniscus complex consisted of the dorsal, intermediate and ventral nuclei. Additionally, the paralemniscal nucleus and the nucleus sagulum were considered. c-fos activation was absent in isolated rats and increased strongly following all types of stimulation in the nuclei of the lateral lemniscus. Labeled nuclei formed bands parallel and perpendicular to the lemniscal fiber tracts. Labeling was scarce in the paralemniscal nucleus and in the nucleus sagulum. These results lead us to conclude that both the superior olivary complex and the nuclei of the lateral lemniscus respond to sound stimuli by activating the c-fos immediate early gene. c-fos activation may play an important role in processing auditory information in these brainstem steps of the auditory pathway.
Keywords: acetylcholinesterase, animal experiment, animal tissue, article, auditory stimulation, controlled study, gene activation, Giemsa stain, histochemistry, immediate early gene, immunocytochemistry, lateral lemniscus nucleus, male, nonhuman, oncogene c fos, rat, superior olivary nucleus