Colocalization of calretinin and calbindin-D28k with oxytocin and vasopressin in rat supraoptic nucleus neurons: a quantitative study.
Recent electrophysiological experiments, in which purified calbindin-D28k (calbindin) and calretinin antibodies were diffused into these neurons, showed that Ca2+-dependent membrane potentials and firing patterns were profoundly and predictably affected by Ca2+-binding proteins (CaBPs). The present study used quantitative analyses of a dual-labeling immunofluorescence method to investigate the colocalization of the CaBPs, calbindin and calretinin in oxytocin (OT)- and (VP)-containing neurons of the supraoptic nucleus. Analyses of tissue immunostained with two different dilutions of each CaBP antibody used, revealed that 84% and 72% of the OT neurons were positive for calbindin immunoreactivity (-ir) at the higher and lower antibody concentrations, respectively. 52% and 50% of OT neurons were positive for calretinin-ir; thus, many OT neurons express both calbindin and calretinin. In contrast, only 25% and 18% of VP neurons showed calbindin-ir, and they were virtually devoid of calretinin-ir. These results provide evidence that CaBP expression in OT neurons is both greater and more diverse than in VP neurons, and are consistent with the hypothesis that Ca2+ buffering capacity contributes to the control of intrinsic firing patterns.
Miyata
S
S
Department of Neuroscience, University of California, Riverside, CA 92521, USA.
Khan
A M
AM
Hatton
G I
GI
D000704:Analysis of Variance; D000818:Animals; D064092:Calbindin 1; D064032:Calbindin 2; D064026:Calbindins; D005455:Fluorescent Antibody Technique; D008297:Male; D009419:Nerve Tissue Proteins / Q000032:analysis; D009474:Neurons / Q000166:cytology*; D010121:Oxytocin / Q000032:analysis*; D051381:Rats; D017207:Rats, Sprague-Dawley; D064030:S100 Calcium Binding Protein G / Q000032:analysis*; D013495:Supraoptic Nucleus / Q000166:cytology*; D014667:Vasopressins / Q000032:analysis*
C576500:Calb1 protein, rat; C576512:Calb2 protein, rat; D064092:Calbindin 1; D064032:Calbindin 2; D064026:Calbindins; D009419:Nerve Tissue Proteins; D064030:S100 Calcium Binding Protein G; D014667:Vasopressins; D010121:Oxytocin