Expression of Calcium Binding Proteins in Olfactory Bulb of Rat: The Effect of Food Restriction

Yeo, Seung Geun; Cho, Joong Saeng; Kim, Kwang Hoon; Huh, Young Buhm; Shim, Hyun Joon; Yoon, Sang Won

Abstract

BACKGROUND AND OBJECTIVES: Food restriction retards aging and increases mean and maximum life span in nearly all species tested thus far. Calcium-binding proteins show a heterogenous distribution in the mammalian central nervous system and are useful markers for identifying neuronal populations. These proteins have been implicated in the buffering and transport of calcium as well as in the regulation of various enzyme systems. We investigated the change of the immunoreactivity of calcium-binding proteins in olfactory bulb of rat after food restriction. MATERIALS AND METHOD: 10 weeks old Sprague-Dawley rat were used in this study. 6 rats were killed at the beginning of the experiment. 30 rats which were restricted food only half of their normal voluntary mean food intake (12 g instead of 24 g per day) were killed at 3 days, 1, 2, 4 and 9 weeks after food restriction (n=6 per time point). Olfactory bulbs of the rats were cut into 40 micro m-thick coronal sections and immunostained.
RESULTS
On the layers of olfactory nerve, glomerular, outer plexiform, granular cell and subependymal zone, immunoreactivities of parvalbumin and calbindin were increased on food restriction week 1 and 2. However, parvalbumin at olfactory nerve layer and calbindin at granule cell layer failed to increase at week 2. Calretinin increased its immunoreactivity at olfactory nerve and outer plexiform layer at week 1. After restriction week 2, immunoreactivity of calcium-binding proteins was almost same as control.
CONCLUSION
The results we obtained from restricted rats indicated that parvalbumin, calbindin and calretinin could be expressed by different manner and layer in olfactory bulb.