Activity-dependent regulation of calcium-binding proteins in the developing rat olfactory bulb

Abstract

Intracellular calcium, important in a variety of second messenger cascades, is regulated in part by calcium-binding proteins such as calretinin, parvalbumin, and calbindin. These proteins are highly concentrated in the rat main olfactory bulb and are localized in distinct neuronal populations. In the present study, postnatal expression was characterized immunohistochemically in normal rats and in rats with functional olfactory deprivation caused by unilateral naris closure, a manipulation that attenuates electrical activity in the bulb. Bulbs were examined from rats that had undergone naris closure or sham surgery on either postnatal day 1 (P1) or P30 and were allowed varying subsequent survival times. Each of the calcium-binding proteins showed both distinct patterns of early expression and differential susceptibility to olfactory restriction. For example, at P10, the densest immunoreactivity was observed for calretinin, a protein whose expression was the least affected by naris closure. After occlusion from P1-P30, there was a 30% reduction in the density of calbindin-immunoreactive profiles in the glomerular layer, and parvalbumin-immunoreactive profiles were reduced by 64% in the external plexiform layer. Unlike many other changes induced by deprivation, the effects of olfactory restriction on calbindin and parvalbumin expression were not age dependent: naris closure from P30-P60 caused similar substantial decreases in calbindin and parvalbumin immunoreactivities. These data demonstrate that the expression of calbindin and parvalbumin in rat bulb is regulated, in part, by afferent activity that is associated with full sensory experiences. The reductions of these calcium-binding proteins following olfactory deprivation are likely to be commensurate with altered control of intracellular calcium.

A Specific Role for NR2A-Containing NMDA Receptors in the Maintenance of Parvalbumin and GAD67 Immunoreactivity in Cultured Interneurons

“…2 A). The expression of PV in cortical neuronal cultures followed a similar developmentally regulated pattern as that described in vivo for rodents and primates (de Lecea et al, 1995;Philpot et al, 1997;Erickson and Lewis, 2002), appearing after 8 -9 d in vitro (DIV8 -9) when the PV-positive subpopulation represented 8% of the GABAergic population (as determined by double immu-nocytochemistry using anti-PV and anti-GAD67 antibodies), and increasing thereafter reaching a plateau at approximately DIV20, when they reached ϳ50% of the GABAergic population (Fig. 2).…”

Glutamatergic Synaptic Dysregulation in Schizophrenia: Therapeutic Implications

“…The levels of expression of these proteins are modulated by afferent synaptic activity (Philpot et al 1997). Parvalbumin is expressed predominantly in chandelier and basket cells in the cortex, which receive direct input from pyramidal neurons.…”

Properties of external plexiform layer interneurons in mouse olfactory bulb slices

“…In addition, EPL interneurons are strongly IR for the glutamate receptor 1 (GluR1) ␣-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptor subunit (Petralia and Wenthold, 1992;Giustetto et al, 1997;Montague and Greer, 1999). Immunoreactivity for GluR1 (Hamilton and Coppola, 2003) and for parvalbumin (Philpot et al, 1997) is greatly reduced following neonatal naris occlusion, a procedure that deprives the olfactory system of airborne odor stimulation and alters olfactory bulb development.…”