ONTOGENY OF SOMATOSTATIN EXPRESSION IN PRIMARY CULTURES OF CORTICAL-NEURONS PARALLELS THAT SEEN INVIVO

The expression of somatostatin (SS) was followed during the development of rat cortical neurons growing in primary cultures. The appearance of SS mRNA is delayed in cultures of cortical neurons, where it is not readily detectable prior to 5 days in culture. Between 5 and 11 days in vitro, there is a large increase in the level of SS mRNA in these cultures. The analysis of SS immunoreactive neurons indicates that they represent a significant proportion of the total neuronal population in these cultures. The majority of these neurons are bipolar or stellate in morphology, although some pyramidal cells are also immunoreactive for SS. More neurons are immunoreactive for SS28 than for SS281-12. Immunoreactivity for SS281-12 is primarily localized throughout the entire soma and neurites, while SS28 reactivity is mainly perinuclear in location. These results indicate that the development of SS neurons in primary cortical culture parallels normal cortical SS ontogeny in vivo, suggesting that these cultures provide a suitable model for the study of intrinsic neocortical peptidergic neurons. © 1990.