Protein malnutrition on suprachiasmatic nucleus cells in rats of three ages.

The effects of prenatal and postnatal protein malnutrition on the major and minor somatic axes of the suprachiasmatic nucleus (SCN) cells of the rat were investigated. Female rats were fed either 6%, 8% or 25% casein diet 5 weeks before mating, during gestation and lactation. After weaning the pups were maintained on the same diet until sacrifice at 30, 90 or 220 days of age. The major and minor axes in fusiform, multipolar and ovoid cells were measured in Nissl-stained SCN slices. Although the 8% diet group displayed significant reductions in fusiform and ovoid cells, the 6% diet group showed the most intense reductions in cell size of the three cell types. In the 6% diet group, cell size was significantly lower at 30 days but the difference with the other nutritional groups ameliorated at 90 days and almost reached control values at 220 days. These data suggest that malnutrition maintained during gestation and postnatal life reduces the somatic size of SCN cells. This alteration may be a morphological substrate underlying sleep and behavioral circadian alterations observed in malnourished rats.