Immunocytochemical characterization of neuron-rich rat brain primary cultures: calbindin D 28K as marker of a neuronal subpopulation

Abstract

The function in neurons of the vitamin D-dependent calcium ion-binding-protein of 28 kDa mol. wt., calbindin D 28K, is unknown. In order to find a simple system for studying the function of this protein, neuron-rich primary cultures derived from brains of 16-day-old rat embryos were analyzed for the presence of calbindin D 28K by immunocytochemical mono- and double-labelling techniques. The studies were carried out between the 5th and 23rd day after seeding. In contrast to the neuronal marker neuron-specific enolase which was found in nearly all cells in the culture, calbindin D 28K was expressed only in a subpopulation of neurons. Calbindin D 28K-positive cells were intensely stained in their cell bodies and were also stained in their processes. Astroglial cells indentified by the presence of the specific marker glial fibrillary acidic protein did not express calbindin D 28K. Therefore, calbindin D 28K is a useful marker for defining a neuronal subpopulation in neuron-rich primary cultures. Such cultures may be employed as a tool in searching for function(s) of calbindin D 28K.