The effect of pyrithioxine and pyridoxine on individual behavior, social interactions, and learning in rats malnourished in early postnatal life.

Abstract

Low protein (LP) or low calorie (LC) dietary regimens were applied in early postnatal life(1st-40th day of life) in male rats. After nutritional rehabilitation, open-field behavior in larger more illuminated boxes (HI, high intensity stimulus), and smaller, less illuminated boxes (HI, high intensity stimulus), and smaller, less illuminated boxes (HI, high intensity stimulus), and smaller, less illuminated boxes (HI, high intensity stimulus), dyadic interactions, and learning ability were investigated in these animals as adults (between the 200th to 300th day of life). LP malnutrition induced an increase of open-field activity with features of sterotypy both in LI and HI situations, an increase number of intersignal reactions during learning procedures without changes in other registered criteria of learning ability (latency, number of correct responses), and an increase of aggressive behavior in pair interaction. LC rats revealed only significant inhibition in LI--open-field activity and a slightly increased number in intersignal reactions during avoidance learning. With the aim of preventing previously described long-term deviations in early malnourished rats, some groups of animals with the above-mentioned early calorie or protein deficits were treated with pyrithioxine (Encephabol Merck) or pyridoxine in 10 doses of 40 mg/kg i.p. administered in the period when nutritional rehabilitation was carried out (between the 40th--50th day of life). The treatment with pyrithioxine reduced significantly behavioral disturbances in adult LP rats except the increase of intersignal reactions which was even potentiated. Pyridoxine was less effective but normalized the increase number of intersignal reactions both in LP and LC rats. The effect of pyridoxine of adult LC rats was interesting. There was significant improvement in all registered parameters of avoidance learning and a significant increase of sexual acts was recorded.