Stimuli from pups of adrenalectomized and malnourished female rats

The present study was designed to examine the effects of maternal adrenalectomy on pup cues. In Experiment 1, pituitary-adrenal activity of test mothers was differentially affected by cues from handled and shocked pups of adrenalectomized (ADX) and control (CON) mothers. The results suggest that the cues provided by pups of ADX mothers are less arousing to lactating females than are cues from pups of CON mothers. In Experiment 2, ultrasonic vocalizations in response to handling and shock were measured in pups of CON, ADX and malnourished (MAL) mothers. For all types of pups, shocking evoked more signaling than did handling on postnatal Days 8, 9 and 11. Pups of CON mothers showed a peak of vocalizations on Day 4. Pups of ADX and MAL mothers vocalized as frequently as did pups of CON mothers, but did not reach their peak of signaling until Day 11. This experiment demonstrates a retardation in the development of ultrasonic signaling in pups of ADX mothers. This effect appears to be due to the pup malnutrition that maternal adrenalectomy produces because pups of MAL mothers show a similar retardation.