Developmental expression of SNAP-25 protein in the rat striatum and cerebral cortex.

The developmental changes of 25-kDa synaptosomal-associated protein (SNAP-25) expression in the rat striatum and cerebral cortex were examined using Western- blotting and densitometric scanning of immunoblots. Analysis of the striatum extracts from postnatal day 0 (P0) to postnatal day 120 (P120) demonstrated that SNAP-25 is poorly expressed until P14. From this point the expression level gradually increases to reach a maximum on P60 and then decreases. The pattern of SNAP-25 expression in the rat cerebral cortex is different. Two peaks are observed, the first on P10 and the second on P60, after which the expression level decreases. These results appear to confirm the role of SNAP-25 protein in axon outgrowth and synaptogenesis in the nervous system.

Developmental pattern of calbindin D28k protein expression in the rat striatum and cerebral cortex.

We examined the protein expression of the calcium-binding protein calbindin D28k in two developing rat brain structures, the striatum and the cerebral cortex. The relative protein concentration level was quantified by means of the Western blotting method and densitometric scanning. 32 Wistar rats were used, divided according to survival period (P0-P120-postnatal days). Observations of the calbindin D28k protein expression in the rat striatum and the cerebral cortex revealed an increase in band color intensity between P0 and P10. The intensity of protein staining in older groups of animals stabilised at a similar level and in the P28 and P120 groups we observed a decrement of calbindin expression in the striatum. Calbindin D28k stabilises the intracellular calcium level, preventing calcium-induced apoptotic cell death in neurons. Thus, changes in calbindin D28k expression might be related to its neuroprotective role in differentiation and synaptogenesis during the postnatal development of the brain.

Developmental changes in nitric oxide synthase protein expression in the rat striatum and cerebral cortex.

We examined the expression of brain nitric oxide synthase (bNOS) in two developing rat brain structures, the striatum and the cerebral cortex. For this purpose, we quantified the relative protein concentration level using the Western blotting method and densitometric scanning. 32 Wistar rats, divided according to survival period (PO-P120-postnatal days) were used in this study. Our results demonstrate that bNOS expression rises in these structures during the first week of postnatal life, reaching a maximum in the striatum on the 10th day and in the cerebral cortex on the 7th day of postnatal life. After the period of increase the expression declines and after the 14th day a stabilisation of bone protein concentration is observed, both in the striatum and the cerebral cortex. These changes in bone protein expression might be related to the important role of nitric oxide in the developing rat brain, especially in synaptogenesis, apoptosis and neurotransmission.

Qualitative and quantitative analysis of the postnatal development of the ventroposterolateral nucleus of the thalamus in rat and rabbit.

The morphometric analysis of changes occurring in the rat and rabbit ventroposterolateral (VPL) nucleus of the thalamus during the postnatal development was performed using unbiased stereological methods. The materials used in the study included 30 Wistar rats and 32 New Zealand rabbits aged from P0 to P180 (P-postnatal day), which were divided into six and eight age groups, respectively. The following stereological parameters of VPL nucleus on the cresyl violet stained sections were determined: volume of the nucleus, numerical density and total number of neurons. The total number of neurons indicated that the development of VPL nucleus in both species ended within the third week of postnatal life. The volume of VPL nucleus increased gradually (by about 2.2 and 5 times in rats and rabbits, respectively) in comparison with the volume of the cerebral hemisphere during the development from P0 to adulthood. The numerical density of VPL neurons decreased rapidly at the beginning of postnatal life and stabilized by the end of the third week. In both species, the gradual increase in the volume of VPL nucleus and the simultaneous decrease in the neuronal density in the first week of postnatal life were mainly caused by changes in the neuropil volume. The total number of cells did not change remarkably during the first postnatal week. However, it decreased significantly during the second week. This decrease was probably due to the naturally occuring cell death. These results show that the most prominent qualitative and quantitative changes in VPL nucleus and its neurons occur during the first two weeks of postnatal life of rats and rabbits. Also, because the thalamocortical relay neurons completely acquire their physiological features, this the most critical period of time for their morphological maturation.