Journal of Neuroscience, Vol 8, 4121-4137, Copyright © 1988 by Society for Neuroscience
Corticotropin-releasing factor in olivocerebellar climbing-fiber system of monkey (Saimiri sciureus and Macaca fascicularis): parasagittal and regional organization visualized by immunohistochemistry
CI Cha and SL Foote
Department of Psychiatry, School of Medicine, University of California, San Diego, La Jolla 92093.
An antiserum directed against the human form of corticotropin-releasing
factor (CRF) was utilized for immunohistochemical visualization of the
distribution of this peptide in the inferior olivary nucleus and cerebellum
of 2 monkey species (Saimiri sciureus, Macaca fascicularis). Colchicine
pretreatment was not used. In both species, immunoreactivity was evident in
the vast majority of neurons in the inferior olivary nucleus, with
perikarya in the medial accessory olive exhibiting especially intense
staining. In cerebellum, no labeled perikarya were present, but
immunoreactive axons exhibiting the morphological characteristics of
climbing fibers and their collaterals were observed in cortical and nuclear
structures. In the cortex, most labeled axons were confined to the
molecular and Purkinje cell layers. In the sagittal plane, individual
axonal arbors originated from thick, isolated axons at the base of the
molecular layer and repeatedly ramified as they extended toward the
cortical surface. In coronal sections, only thin, paired profiles were
present. Labeled processes also formed efflorescences in the granular layer
of cortex and were evident as highly arborized axons in cerebellar nuclei.
In each of these instances, the labeled elements resembled climbing fibers
or their collaterals as visualized by other methods. Other labeled
processes in the granular layer exhibited the morphological characteristics
of mossy fiber axons. Immunoreactive, climbing-fiber- like axons were
present in the molecular layer throughout the major regions of cerebellar
cortex. However, the most intensely labeled of these axons were strikingly
clustered within particular regions and parasagittal domains. In the vermis
and intermediate zone, intensely labeled axons were present only within
parasagittal zones similar in location to those defined by climbing fiber
innervation from the medial accessory olive. Intensely labeled axons were
also densely but uniformly distributed within the uvula, the medial region
of the dorsal paraflocculus, and the dorsal region of the pyramis, areas
that receive their climbing fiber input primarily from the medial accessory
olive. Labeled fibers were much less dense and were not clustered in the
lateral hemispheres. The present observation of CRF-like immunoreactivity
in the monkey olivocerebellar pathway is compatible with the previous
observation of CRF mRNA within olivary neurons of rat, baboon, and human
(Young et al., 1986) and with recent immunohistochemical findings in rat
(Sakanaka et al., 1987; Palkovits et al., 1987), cat (Cummings et al.,
1988; Kitahama et al., 1988), sheep (Cummings et al., 1988), and human
(Powers et al., 1987).(ABSTRACT TRUNCATED AT 400 WORDS)