ABSTRACT
Albino rats undernourished from the 18th day of gestation until 140 days of age, with some of rats being nutritionally rehabilitated between 70 and 140 days of age. Control and experimental rats were anaesthetised and perfused with 2.5% gluteraldehyde at each of 70 and 140 days of age. Pieces of cerebellar tissue from each rat were postfixed in osmium tetroxide and embedded in resin. Stereological procedures at high and electron microscope levels were used to estimate the numerical density [Nv] of granule cell neurons and synapses as well as the synapse-to-neuron ratio. No obvious qualitative differences in the ultrastructural morphology within the granular cell layer were observed between control, undernourished and nutritionally rehabilitated rats. Undernourished rats had significantly lower body and cerebellar weight than control at all ages examined. These deficits persisted even after a period of nutritional rehabilitation. The Nv of granule cells showed no significant difference between the undernourished and control groups at 70 and 140 days of age. However, nutritional rehabilitation caused significant deficit in the Nv of granule cells in rats rehabilitated from 70 to 140 days of age compared with control ones. At 70 days of age, undernourished rats showed non significant deficit in the Nv of synapses compared with control rats. However, by 140 days of age, there was a significant increase in the synaptic density of the undernourished rats compared with control. The synaptic density was not significantly different between the nutritionally rehabilitated animals and control ones. The synapse-to-[granule cell] neuron ratio showed a significant deficit [14%] in the undernourished rats at 70 days of age compared to the control group. This was reversed by the age of 140 days when the undernourished rats had a significant greater [11%] synapse-to- [granule cell] neuron ratio despite continuing the undernutrition. However, 140 days old rats nutritionally rehabilitated from 70 days of age showed significant increase [19%] in this ratio compared with well-fed controls. It was concluded that a lengthy period of undernutrition can cause an initial deficit in the synapse-to-neuron ratio in the rat cerebellum. This deficit was not permanent, but it completely disappeared despite continued undernutrition. Moreover, this deficit was changed to a significant increase in both rats continuously undernourished and also in the nutritionally rehabilitated ones so, the nutritional rehabilitation was not prerequisite to restore the deficit in this ratio induced by a period of undernutrition