Vulnerability of developing brain. II. Effects of early nutritional deprivation on reflex ontogeny and development of behaviour in the rat

Abstract

During the last two weeks of pregnancy and throughout lactation the food intake of a group of female rats was restricted to about half that of a control group fed ad libitum. The growth, physical maturation and behavioural development of control and undernourished male offspring were compared. At 21 days the body weight of the underfed young was only one-third that of controls. The appearance of 2 out of 3 physical features, and of 4 out of 8 reflexes was significantly delayed in the undernourished group. Generally, characteristics which normally appear in the first week of postnatal life were not significantly affected; whereas most of those appearing later were significantly delayed. When rats were 9, 13, 17 and 21 days old their behaviour in an open field was observed. Exploratory responses were first seen significantly later in undernourished young. Though they moved about the field as much as the controls, they made significantly fewer upward-directed responses on the first 3 days of testing. At 21 days most control rats were able to move round the rim of a plastic beaker to a refuge platform, a feat accomplished by only a few underfed animals.