The selective neurotoxin DSP-4 impairs the noradrenergic projections from the locus coeruleus to the inferior colliculus in rats

• DOI: 10.3389/fncir.2012.00041
• Publication Date: 2012-06-28T10:16:54Z
• Authors: Sebastián Hormigo; José de Anchieta ...; Ricardo Gómez-Nieto; Dolores E. López
• Keywords: Locus coeruleus; Superior colliculus; Colocalization; Biotinylated dextran amine

The inferior colliculus (IC) and the locus coeruleus (LC) are two midbrain nuclei that integrate multimodal information play a major role in novelty detection to elicit an orienting response. Despite reciprocal connections between these structures, projection pattern target areas of LC within subdivisions rat IC still unknown. Here, we used tract-tracing approaches combined with immunohistochemistry, densitometry, confocal microscopy (CM) analysis describe from IC. Biotinylated dextran amine (BDA) injections into showed LC-IC is mainly ipsilateral (90%) reaches, extent, dorsal lateral part intercollicular commissure. Additionally, some fibers extend central nucleus neurochemical nature this noradrenergic, given tyrosine hydroxylase (TH) dopamine beta (DBH) colocalize BDA-labeled LC. To determine total field innervations IC, destroyed neurons using highly selective neurotoxin, DSP-4, then studied distribution density TH- DBH-immunolabeled axons In DSP-4 treated animals, number axonal immunolabeled for TH DBH were deeply decreased throughout entire rostrocaudal extent its compared controls. Our densitometry results receives up 97% noradrenergic only 3% non-coeruleus neurons. also indicate immunoreactivity was less impaired than after administration. This consistent existence important dopaminergic substantia nigra conclusion, our study demonstrates quantifies subdivisions. re-examination treatment provides insights source, topographic efferent network hence, contributes understanding noradrenaline (NA) system auditory processing.