The site of origin of calcitonin gene-related peptide-like immunoreactive afferents to the inferior olivary complex of the mouse.

Peltier AC, Bishop GA
Neurosci Res. 1999 34 (3): 177-86

PMID: 10515260 · DOI:10.1016/s0168-0102(99)00045-0

The intent of the present study is to define the brainstem nuclei which give rise to CGRP-immunolabeled afferents to the inferior olivary complex of the mouse. A technique which combines retrograde transport of fluorescent microspheres with immunohistochemistry was used to address this question. In the present study, intensely labeled CGRP neurons were localized within several cranial nerve nuclei including the hypoglossal, facial, oculomotor, motor nucleus of the trigeminal nerve and nucleus ambiguus, as well as in the parabrachial nucleus, locus coeruleus and medullary and pontine reticular formation. In addition, lightly labeled CGRP neurons were identified within the deep cerebellar nuclei, the inferior olivary complex, lateral reticular nucleus, medial and lateral vestibular nuclei, nucleus Darkschewitsch, interstitial nucleus of Cajal, the central gray area adjacent to the third ventricle, and the zona incerta. The origin of the projection to the inferior olivary complex primarily arises from the deep cerebellar nuclei, the locus coeruleus, and the central gray matter of the mesodiencephalic area. In addition, a small CGRP input is derived from the superior and lateral vestibular nuclei as well as the zona incerta. In conclusion, we have identified several extrinsic sources of CGRP to the inferior olivary complex and have localized it within afferents that have been shown to have either excitatory (mesodiencephalic nuclei) or inhibitory (cerebellar nuclei) effects on olivary circuits. The presence of CGRP in these functionally diverse brainstem and cerebellar afferents suggests that the peptide may act as a co-transmitter to modulate the activity of olivary neurons.

MeSH Terms (12)

Animals Brain Stem Calcitonin Gene-Related Peptide Fluorescent Dyes Immunohistochemistry Injections, Intraperitoneal Mice Mice, Inbred C57BL Microscopy, Fluorescence Microspheres Neurons, Afferent Olivary Nucleus

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