Distribution and densitometry mapping of LI-CAM immunoreactivity in the adult mouse brain - Light microscopic observation

Abstract

Background: The importance of LI expression in the matured brain is suggested by physiological and behavioral studies showing that LI is related to zzzhippocampal plasticity and fear conditioning. The distribution of LI in mouse brain might provide a basis for understanding its role in the brain. Results: We examined the overall distribution of LI in the adult mouse brain by immunohistochemistry using two polyclonal antibodies against different epitopes for LI. Immunoreactive LI was widely but unevenly distributed from the olfactory bulb to the upper cervical cord. The accumulation of immunoreactive LI was greatest in a non-neuronal element of the major fibre bundles, i.e. the lateral olfactory tract, olfactory and temporal limb of the anterior commissure, corpus callosum, stria terminalis, globus pallidus, fornix, mammillothalamic tract, solitary tract, and spinal tract of the trigeminal nerve. High to highest levels of non-neuronal and neuronal LI were found in the grey matter; i.e. the piriform and entorhinal cortices, hypothalamus, reticular part of the substantia nigra, periaqueductal grey, trigeminal spinal nucleus etc. High to moderate density of neuronal LI was found in the olfactory bulb, layer V of the cerebral cortex, amygdala, pontine grey, superior colliculi, cerebellar cortex, solitary tract nucleus etc. Only low to lowest levels of neuronal LI were found in the hippocampus, grey matter in the caudate-putamen, thalamus, cerebellar nuclei etc. Conclusion: LI is widely and unevenly distributed in the matured mouse brain, where immunoreactivity was present not only in neuronal elements; axons, synapses and cell soma, but also in non-neuronal elements. © 2003 Munakata et al; licensee BioMed Central Ltd.