Combined effects of moderate ethanol consumption and a low-protein diet during gestation on brain development in BALB/c mice

Early malnutrition favours heavy ethanol intake in weaning rats without long-lasting effects

INTRODUCTION

Although food restriction is well known to increase ethanol intake, the subject has not been extensively studied in developing animals which could be more vulnerable to long-lasting effects. Therefore, the aim of this study was to show some findings concerning this subject.

MATERIALS AND METHODS

Food restriction was used to produce malnutrition either during lactation (lactating dams food restricted 60%) or after weaning (pups food restricted 60%). At weaning, day 25, males were assigned to one of the following groups: C, food ad libitum throughout the experiment - control group; MW, malnourished only after weaning; ML, malnourished only during lactation period; and MLW, malnourished throughout the experiment, during lactation and after weaning. All rats were kept isolated in cages in which they could choose to drink either a 10% ethanol solution or tap water (from days 25 to 45). Re-exposure to this model was performed on day 49. Between exposure and re-exposure, rats drank tap water for 4 days.

RESULTS

There was a significant effect of malnutrition during lactation, up to day 35, with heavy drinking patterns (ethanol intake day 2: C, 8 g/kg; MW, 9 g/kg; ML, 19 g/kg; and MLW, 22 g/kg). This heavy drinking pattern lasted until the recovery of body weight. Food restriction after weaning had significant effects after 14 days, when a statistically significant decrease in body weight occurred (body weight day 39: C, 147.8 g; MW, 98.5 g). Only rats which were persistently malnourished (MLW and MW) drank ethanol more significantly than their ad libitum-fed counterparts during the re-exposure period (ethanol intake: malnourished, 5 g/kg; and well-nourished, 2.5 g/kg). Adulteration of the ethanol solution with quinine (0.1 g/l) precluded the effect of malnutrition.

CONCLUSIONS

Malnutrition during early development had no long-lasting effects on ethanol consumption. In addition, malnutrition increased ethanol consumption as long as it kept body weight low, which was apparently more significant in young animals.

Thalamocortical maturation in mice is influenced by body weight

The emergence of the whisker-related patterning of the barrel cortex during the first postnatal week is a frequently assessed feature of rodent cortical development and has been used extensively to screen for effects of genetic mutations on neural development in mice. As alterations in body weight often accompany genetic mutations, we asked whether body weight itself might affect the progression of barrel cortex development in wildtype C57/BL6 mice. The body weight varied considerably between as well as within litters, and could differ by a factor of up to 1.6 between littermates. The establishment of the periphery-related and barrel patterning was assessed at postnatal (P days) 4 and 6 using cytochrome oxidase and Nissl staining. We found that only 20% of the mouse pups had an established thalamocortical afferent pattern in the barrel cortex at P4 (4 out of 21 brains), while the majority of the pups showed a well-established pattern at P6 (13 of 16 brains). At both ages the more developed barrel structure was found in the heavier littermates. Conversely, no periphery-related pattern was apparent in the somatosensory cortex at either P4 or P6 below a critical body weight of 2.6 g and 2.0 g, respectively. These findings may have implications for the interpretation of developmental changes in the barrel cortex of genetically modified mice.

Interactive effects of ethanol intake and maternal nutritional status on skeletal development of fetal rats

Skeletal development on gestation day 21 was examined in fetuses of alcohol-consuming (A), pair-fed (PF) and ad lib-fed (C) Sprague-Dawley females. Ethanol (36% ethanol-derived calories) was administered in liquid diets that were marginal (Diet A1) or optimal (Diet A2) in terms of pregnancy requirements (18% vs. 25% total calories as protein, respectively). For each bone studied, a lengthwise measurement was made of the whole bone and of the ossified portion(s), and percent ossification was calculated. Number of sternebral ossification centers present was also determined. Alcohol-exposed fetuses showed retarded ossification of the tibia and radius, regardless of maternal protein intake. Increasing the protein content of the alcohol diet from 18% (Diet A1) to 25% (Diet A2) significantly increased ossification of the ulna, sternum, humerus and ilium-ischium. For the ulna, A2 fetuses showed greater ossification than A1 fetuses but were still retarded compared to PF and C fetuses. For the sternum, humerus and ilium-ischium, however, ossification in A2 fetuses increased to the levels observed in the PF and C groups. In addition, number of sternebral ossification centers present was significantly increased in A2 compared to A1 fetuses. These data indicate that skeletal development provides a sensitive index of ethanol-induced developmental delay as well as interactive effects of ethanol and nutrition.