SOMATOSTATIN EXPRESSION IN TS16 MOUSE-BRAIN CULTURES

Somatostatin expression in trisomy 16 mouse neuronal cultures has been studied to investigate the effects of the presence of an extra copy o f the pre-pro-somatostatin (ppSS) gene on mouse chromosome 16. The imm unoreactivity for somatostatin (SS) was considered in mixed cultures o f neurons and glia cells and in neuron-enriched cultures as well as th at for neuropeptide Y, glutamic acid decarboxylase, and gamma-enolase immunoreactivity the genes of which are not present on mouse chromosom e 16. ppSS and pre-pro-neuropeptide Y (ppNPY) mRNA expression was eval uated and SS immunoreactivity in neurons analyzed by a morphometrical study. The extra copy of the ppSS gene resulted in a significantly inc reased level of the transcript in trisomic cultures, whereas the expre ssion of the other neuropeptides did not differ. The absence of glial cells in these cultures reduced the number of SS-positive neurons maki ng their number comparable in the trisomic and control cultures. Thus, in spite of higher expression of the ppSS mRNA in trisomic cultures, the determination of this peptidergic phenotype was influenced by the presence of neuroglial cells.