Effect of undernutrition on developing rat cerebellum. Some electrophysiological and neuromorphological correlates.

Electrophysiological studies of Purkinje cells from the developing normal and undernourished rat cerebellar cortex were correlated with the neuromorphological studies. In undernourished animals the firing pattern of Purkinje cells was simpler as compared to complex electrical activity in normal animals. The firing frequency of Purkinje cells remained reduced in all the age-matched undernourished groups. The duration of a spike was also prolonged as compared to their normal age mates. Similarly the mean amplitude was also relatively smaller in the undernourished animals when compared with the normal litter mates. Undernourished animals exhibited typical increased stimulus thresholds, prolonged N-2 peak wave latencies, reduced number of functional components, amplitude and increased duration of mossy fiber response (MFR). The mossy fiber (MF) activity exhibited a sluggish rise in its amplitude, when stimulus intensity was increased in undernourished animals. A phenomenon of fatigue was observed with a significant reduction in the amplitude and frequency of Purkinje cell unit discharge on repeated MF stimulation in the undernourished animals. However, repeated MF stimulation provided a high frequency discharge in the normal as well as undernourished adult rats. Neuromorphological studies at light-microscopic level exhibited delayed cell migration from the external granular layer in the undernourished rats. At electron-microscopic level, intracellular morphology exhibited almost similar ultrastructural details except for a few minor alterations. A free ribosomal pool, immature development of E.R., increased incidence of lysosomes and electron-dense membrane stacks were observed in the Purkinje cells at 30 days in the undernourished animals. The results of the present study indicated that undernutrition affects the maturation of Purkinje cell regional neurocircuitry.