Calretinin and calbindin-D28k in dopaminergic neurons of the rat midbrain: a triple-labeling immunohistochemical study.
We used triple-labeling immunohistochemistry in rat midbrain sections to identify dopaminergic neurons that contain either one or both of the calcium-binding proteins, calretinin (CR) and calbindin-D28k (CB). Midbrain dopaminergic neurons were immunohistochemically labeled for tyrosine hydroxylase (TH), CR, and CB. In the substantia nigra pars compacta (SNC), TH+/CR+/CB+ cells were clustered in two regions: the dorsal tier of the rostral SNC and the medial part of the intermediate SNC. The ventral tier of the rostral SNC mainly comprised both TH+/CR+/CB- and TH+/CR-/CB- cells. The lateral part of the intermediate SNC and the caudal SNC primarily consisted of TH+/CR-/CB- cells. Throughout the extent of the SNC, approximately half of the TH+ neurons were stained for neither CR nor CB, while the remaining TH+ populations were labeled for CR and/or CB. Throughout the ventral tegmental area, TH+/CR+/CB+ cells, TH+/CR+/CB- cells, TH+/CR-/CB+ cells, and TH+/CR-/CB- cells were found generally scattered, though the TH+/CR-/CB- cells were dominant in number. In the substantia nigra pars lateralis, interfascicular nucleus, and caudal linear nucleus, more than half of the TH+ cells were stained for both CR and CB. In the retrorubral field, two-thirds of the TH+ neurons contained neither protein. The present findings suggest that the SNC can be divided into subcompartments based on the distribution of dopaminergic neurons that contain calcium-binding proteins. Furthermore, because CR and CB likely contribute to calcium homeostasis by buffering intracellular calcium concentrations, midbrain dopaminergic neurons containing one or both of these calcium-binding proteins may have a higher calcium-buffering capacity than those lacking the two proteins.
Nemoto
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C
Department of Anatomy, Fujita Health University School of Medicine, Toyoake, Aichi 470-1192, Japan.
Hida
T
T
Arai
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R
D000818:Animals; D064092:Calbindin 1; D064032:Calbindin 2; D064026:Calbindins; D004298:Dopamine / Q000502:physiology; D005455:Fluorescent Antibody Technique; D008297:Male; D009474:Neurons / Q000737:chemistry* / Q000201:enzymology; D051381:Rats; D017207:Rats, Sprague-Dawley; D064030:S100 Calcium Binding Protein G / Q000032:analysis*; D013378:Substantia Nigra / Q000737:chemistry / Q000166:cytology*; D014446:Tyrosine 3-Monooxygenase / Q000032:analysis; D017557:Ventral Tegmental Area / Q000737:chemistry / Q000166:cytology*
C576500:Calb1 protein, rat; C576512:Calb2 protein, rat; D064092:Calbindin 1; D064032:Calbindin 2; D064026:Calbindins; D064030:S100 Calcium Binding Protein G; D014446:Tyrosine 3-Monooxygenase; D004298:Dopamine