Immunohistochemical Study on the Changes of Neuropeptide Y Immunoreactive Neurons in the Corpus Striatum and Motor System of Aged Rat / 대한해부학회지

Decreased number of the Neuropeptide-Y[NPY] immunoreactive neurons in the corpus striatum and primary motor cortex of aged rat was detected by the immunohistochemical method. The animals were categorized into control and aged group and we used 10 Sprague-Dawley rat weighing 250-300gm for control group. 10 Sprague-Dawley rat weighing over 600gm for aged group. The number of NPY-immunoreactive neurons in corpus striatum and primary motor cortex were counted under the light microscope and the following results were obtained. 1. The NPY-immunoreactive neurons were evenly distributed in corpus striatum and in the primaty motor cortex, the NPY-immunoreactive neurons were concentrated within the layer II, III and layer V, VI. The typical NPY-immunoreactive perikarya was multipolar shape. 2. Decreased number of NPY-immunoreactive neurons were detected in some areas of corpus striatum and primary mortor cortex of the aged rat. 3. Decrease of NPY-immunoreactive neurons were most prominent in the caudate-putamen and there were moderate decrease of NPY-immunoreactive neurons in the primary motor cortex, mild decrease of NPY-immunoreactive neurons in the nucleus accumbens but the NPY-immunoreactive neurons were not observed in the globus pallidus in both control and aged rat. NPY is supposed to act as a neurotransmitter of local circuit neurons in the striatum and may exert its potent vasoconstrictor effects on cerebral vessels which influences on the microcirculation of cerebral cortex and striatum. So our results seems to provide an important data on change of the function in the striatum and primary motor cortex of aged rat brain.

Double Immunohistochemical Study on the Postnatal Development of Somatostatin - and Neuropeptide Y - Immunoreactive Neurons in Rat Cerebral Cortex / 대한해부학회지

The postnatal development of somatostatin [SOM]- and neuropeptide Y[NPY]- immunoreactive[ir] neurons were examined in rat cerebral cortex considering their coexistence in cortical neurons. Using double immunohistochemical staining for SOM and NPY with diaminobenzidine and benzidine dihydrochloride as chromogens, we subdivided immunoreactive cells into double-labeled SOM/NPY-, SOM only-, and NPY only-ir neurons. Interestingly, SOM/NPY- and SOM only-ir neurons were detectable even at the day of birth, in contrast to NPY only-ir cells which first appeared in most cortices from two weeks of age. The morphological features of double-labeled SOM/NPY neurons were not identical to those SOM only- and NPY only-ir neurons. No apparent changes in the shape and size of single-labeled neurone occurred with age ; throughout their postnatal life they were round and ovoid, had a thin rim of perinuclear cytoplasm, and short processes. In contrast, the features of SOM/NPY-ir neurons were not consistent during postnatal life. By day P7, these neurons showed immature features ; they began to show more advanced neuronal characteristics by week P2, when they had a larger and more intensely-stained cytoplasm. In addition, their processes were longer, thicker and more complex than at earlier ages. At this age, SOM/NPY-ir somata were close to their maximum size. From week P4, they became smaller and were lightly labeled. SOM/NPY-ir somata were larger than SOM only- and NPY only-ir somata at and after two weeks of age. The present results showing different postnatal maturation patterns such as time of appearance and morphological features suggest that double-labeled SOM/NPY and single-labeled neurons might be different populations regulated by different mechanisms in their development, and with different functional properties during development.