A fractionator study of the effects of undernutrition during early life on rat Purkinje cell numbers (with a caveat on the use of nucleoli as counting units)

Abstract

The effects of varying periods of general protein-calorie undernutrition during early life on Purkinje cells in the cerebellum of the rat were examined. In Experiment 1, animals were undernourished from d 18 of gestation until either d 30 or d 60 of postnatal age, followed in some cases by a period of nutritional rehabilitation. In Experiment 2, rats were undernourished from conception until d 30 postnatally, followed by a period of rehabilitation until 60 d of age. The 'fractionator' method was employed to estimate the total number of cerebellar Purkinje cell nucleoli. If each cell has one nucleolus, this number is equal to the number of Purkinje cells. In Experiment 1, the estimated mean number of Purkinje cell nucleoli varied between 188,000 and 273,000 for the groups of animals studied. However, the interanimal variation was large and 2-way analysis of variance tests failed to reveal any statistically significant age, nutrition or interaction effects. In Experiment 2, rats killed immediately after the period of undernutrition possessed significantly fewer Purkinje cell nucleoli than age-matched controls. This did not represent a real decrease in cell number. Instead, the result could be explained by a change of Purkinje cell morphology in undernourished rats. The change included nucleolar regression. Nutritionally rehabilitated animals had similar numbers of nucleoli to control rats. It is concluded that the levels and periods of undernutrition used in these experiments did not affect significantly the total numbers of cerebellar Purkinje neurons.