Effect of nicotine on the postnatal development of the cerebellar cortex of the albino rat.

摘要

The cerebellum is a crucial component in the neuron circuit responsible for muscle coordination, posture, locomotion and head position. The aim of this study was to clarify the effect of nicotine on the postnatal development of the cerebellar cortex in albino rats. 80 rats were divided into control and experimental groups. The experimental group included the offspring of nicotine treated mothers. Nicotine free base was administered to the pregnant rats from the 14th day of gestation until birth and during the whole period of lactation. The dose of nicotine used in this study was 6 mg/kg/day. Nicotine was injected subcutaneously in a single dose. Eight animals in both control and nicotine treated groups were sacrificed at 0 (newborn), 7, 15, 21 and 60 days of age. Samples of the cerebellar cortex were processed for study by transmission electron microscopy. The thickness of the cerebellar cortical layers (molecular, purkinje and internal granular layers) and the number of cells in the internal granular layer per field (12060 micron2) were measured and statistically analysed. It was shown that there was complete disappearance of the external granular layer at 21 days of age in the control group while was present in the nicotine-treated group after this age. In the nicotine treated group, the purkinje cell layer remained as a multicellular layer until 15 days of age in comparison with the control group which attained the typical monocellular pattern by the end of the first week. Several cavities appeared to be present in the internal granular layer of nicotine-treated group. The ultrastructural study of purkinje neurons of the nicotine-treated group showed the presence of many degenerative changes. The thickness of the cerebellar cortical layers and the number of cells in the internal granular layer significant decreases in the nicotine-treated group at all ages compared with that of the control. In conclusion, nicotine could induce delayed cerebellar development with neuronal damage. Cigarette smoking is recommended to be prohibited during pregnancy and through the period of lactation.