Thermoregulatory deficits following prenatal alcohol exposure: structural correlates

Prenatal exposure to alcohol delays the development of thermoregulation in newborn rats. This study examined two possible physiological correlates of this effect. In the first experiment, the effect of prenatal alcohol exposure on the availability of brown adipose tissue for nonshivering thermogenesis was investigated in rat pups from birth to weanling age. Male and female pups were chosen from independent litters with one of three prenatal treatment histories: 35% ethanol-derived calories (35% EDC), pair-fed control (0% EDC), or lab-chow control (LC). Prenatal alcohol exposure resulted in decreased body weight from postnatal (PN) day 1 to 20 compared to controls. Similarly, alcohol-exposed subjects had lighter interscapular brown adipose tissue pads than controls. However, the proportion of brown adipose tissue to body weight in alcohol-exposed pups was not different from controls. It appears that thermoregulatory deficits at birth due to prenatal alcohol exposure are not due to decreased substrate availability. In the second experiment, the relative growth rate of the tail compared to the growth rate of the body was measured in male and female pups from the three prenatal treatment groups. Five-day-old rat pups exposed to alcohol prenatally had relatively slower tail growth than control pups. Since tail growth rate has been associated with ambient temperature, these results suggest that alcohol-exposed rat pups may be experiencing transient periods of cold stress in the nest because of their thermoregulatory deficiencies, which, in turn, could have important implications for neural and body growth retardation seen in Alcohol Related Birth Defects.