$142

ONTOGENY OF SOMATOSTATIN IN THE CEREBRAL CORTEX OF THE MACAQUE MONKEY: AN IMMUNOHISTOCHEMICAL STUDY.

AKIKO YAMASHITA, MOTOHARU HAYASHI, KEIKO SHIMIZU and KIYOSHI OSHIMA* Primate Research Institute, Kyoto University, Kanrin, Inuyama, Aichi 484, Japan

The regional distribution and ontogeny of somatostatin in the cerebral cortical subdivisions of the macaque monkey were studied by radioimmunoassay (HAYASHI and OSHIMA 1986). The present study was performed to clarify the patterns of somatostatin cells at 4 different stages (embryonic 140-days, new- born, postnatal 60-days and adult) of the macaque monkey by an immunohisto- chemical method (Avidin Biotin Complex method). The number of somatostatin cells in all cell layers and white matter were higher in the earlier stages than during the adult stage. During development, the number of somatostatin cells became smaller, especially in layer IV and the white matter. During the adult stage, somatostatin cells localized in layer II, upper layer III, and layers V and VI. The number of somatostatin cells were low in the white matter. Among the cerebral subdivisions, there exist differences in development of somatostatin cells. At embryonic 140-days, the number of somatostatin cells in the parietal and prefrontal cortex was more than in any other area. There were more cells in the prestriate cortex than in the striate cortex at embryonic 140-days. The number of cells in the striate cortex did not change during development. Therefore, at the adult stage, more cells exist in the striate cortex than in the prestriate cortex. The larger number of somatostatin cells in all layers during the earlier developmental stages suggest that somatostatin may participate in the development of the monkey cerebral cortex.

POSTNATAL DEVELOPMENT OF CHOLECYSTOKININ-LIKE IMMUNOREACTIVITY AND ITS mRNA LEVEL IN RAT BRAIN REGIONS

+* KATSUMICHI TAKEDA~ HIROYUKI KOSHIMOTO~ FUMIAKI UCHIUMI~ RANDY S. HAUN, JACK E. DIXONt~ND TAKESHI KATO, Department+of Life Chemistry, Tokyo Institute of Technology, Yokohama 227, Japan and Purdue Univ., West Lafayette, IN 47907, USA.

Developmental changes of preprocholecystokinin mRNA(CCKmRNA) and cholecys- tokinin-like immunoreactivity(CCK-LI) were examined in rat brain regions(frontal cortex,eolliculi, hippocampus, striatum, and cerebellum) using RNA dot blots assay with CCKcDNA and a radioimmunoassay, respectively. The CCK-LI levels in all regions examined were very low at birth. These levels, except in the cerebellum, increased postnatally and reached adult levels at 28 days of age. The cerebellum contained a small amount of CCK-LI during development. On the other hand, changes in the CCKmRNA level were different from those of CCK-LI. The frontal cortex already contained a small amount of CCKmRNA at birth. The levels of CCKmRNA increased rapidly during 7-14 days of age and showed maximal values during 21-28 days of age. The adult values amounted to 75% of the maximal mRNA levels. The increase of CCK-LI in the frontal cortex was preceded by a corresponding increase in CCKmRNA. The CCKmRNA levels in the colliculi showed a rapid increase during 7- 14 days of age and attained adult level, including the moderate decrease, during 14-28 days of age. CCKmRNA levels in the hippocampus and striatum showed a single peak at 14 days of age. In the adult brain the CCKmRNA levels were high in the frontal cortex, medium in the hippocampus and colliculi, and low in the striatum. The cerebellum contained only a negligible amount of CCKmRNA during development. The CCK-LI levels in the striatum were relatively high, whereas the CCKmRNA levels were low during development. These data support the idea that the majority of striatal CCK-LI are supplied from extrastriatal regions. Finally, our data show that increasing of the CCK-gene expression and/or numbers of CCK neurons may occur during 7-14 days of age, and the different regulation of CCK-gene expression and the different post-transcriptional regulatory mechanism may exist in the various brain region during development.