Effects of early-life undernutrition in artificially reared rats: subsequent body and organ growth

Abstract

I. Four groups of rat pups were reared: mother-reared (MR) control (well-fed) and undernourished (MRC and MRU respectively) and artificially reared (AR) control and undernourished (ARC and ARU respectively). Pups for artificial rearing were fitted with a gastric cannula on postnatal day 5 and were fed, by intermittent gastric infusion, expressed rats' milk (days 5-7), mixtures of rats' milk and milk-substitute (days 8-16), and milksubstitute only (days 17-20). Solid food was available to MR pups throughout and to AR pups from day 14. Undernutrition, imposed from postnatal days 5 to 25, was effected initially by underfeeding the mother (MRU) or by infusing restricted quantities of milk (ARU). Weaning was at 21 d and undernutrition from day 21 to day 25 was by restricting the supply of solid food. A11 rats were fed ad lib. from 25 d.2. The developmental milestone, eye-opening, was delayed by undernutrition but unaffected by artificial rearing.3. Growth curves in body-weight during the refeeding phase were influenced most by previous undernutrition and to a lesser extent (also negatively) by artificial rearing. 4.Fourteen measures of body and organ growth were taken at autopsy at 39 weeks. Twelve measures were affected by nutrition and only four by rearing (weight of whole body, epididymal fat pads, renal fat pads and adrenals).5. AR rats had lighter epididymal and renal fat pads than MR rats perhaps due to the low fat content of the expressed milk they received early in artificial rearing.

An F1-Extended One-Generation Reproductive Toxicity Study in Crl:CD(SD) Rats With 2,4-Dichlorophenoxyacetic Acid

“…In humans, the metabolic demands of breastfeeding require an increase in maternal metabolism of approximately 20% or less (Frigerio et al , 1991; Prentice and Whitehead, 1987). This contrasts markedly with laboratory rodents, where nutrient intake is critical for lactation success because a large portion of the metabolic output is directed to milk synthesis (Grigor et al , 1987; Smart et al , 1987). …”

Mild carbon monoxide exposure and auditory function in the developing rat

“…1A) through which the milk substitute is pulse‐fed from an infusion syringe for up to 30 min in each hour over the 24‐hr day before the milk is replenished and the system maintained. AR rats can be weaned from the milk substitute at 19–20 days of age to develop to adulthood (Smart et al, 1987, 1989). This model eliminates variables introduced from maternal influences because the mother rat is not a component of the test or control groups (O'Connor et al, 1988).…”

Standardised Parenteral Nutrition

“…It is becoming clear that early nutrition in the critical period plays an important role in the long-term health and neuro-development. Experimental studies in animals have shown that nutrition in the critical period of life can affect brain structure and function irreversibly [11,12]. Postnatal nutrition in rat male pups was shown to affect dendritic branching in certain locations of rat brain, important in regulating attention status and the integration of motor and sensory activity, and this effect persisted in spite of later correction of nutritional deficits [13].…”