title: The relationship of calbindin-containing neurons with substance P, Leu-enkephalin and cholecystokinin fibres: an immunohistochemical study in the rat thalamus.
abstract: In the rat thalamus, immunoreactivity for the calcium binding protein calbindin (Cb) is mostly confined to neuronal cell bodies, sometimes revealing proximal dendrites, of the midline, intralaminar and posterior regions. Substance P (SP)-, cholecystokinin (CCK)- and Leu-enkephalin (L-ENK)-immunoreactive (ir) elements in the thalamus are fibre-like structures, intermingled with punctate elements probably representing axonal arborizations and their synaptic boutons. These peptidergic fibres are unevenly distributed in several thalamic domains, including the areas that contain Cb-ir neurons. The relationship between Cb-ir cell bodies and these three different peptidergic systems of thalamic innervation was studied with immunohistochemistry. Single-labelling experiments on adjacent sections and double immunostaining on the same section were performed. A considerable overlap between Cb-ir perikarya and SP-ir fibres was found in most thalamic nuclei. In particular, in the intralaminar nuclei and posterior complex, SP-ir punctate elements were frequently observed in close proximity to Cb-ir cell bodies and dendrites. On the other hand, no consistent topographical correspondence between Cb-ir perikarya and CCK- or L-ENK-ir fibres was evident. Altogether, the present data suggest a selective anatomical and, possibly, functional relationship between SP and Cb in at least a subpopulation of rat thalamic neurons.
mesh_terms: D000818:Animals; D064026:Calbindins; D002766:Cholecystokinin / Q000032:analysis*; D004743:Enkephalin, Leucine / Q000032:analysis*; D007150:Immunohistochemistry; D009412:Nerve Fibers / Q000737:chemistry*; D009474:Neurons / Q000737:chemistry*; D051381:Rats; D017207:Rats, Sprague-Dawley; D064030:S100 Calcium Binding Protein G / Q000032:analysis*; D013373:Substance P / Q000032:analysis*; D013788:Thalamus / Q000737:chemistry*
chemical_list: D064026:Calbindins; D064030:S100 Calcium Binding Protein G; D013373:Substance P; D004743:Enkephalin, Leucine; D002766:Cholecystokinin