Somatostatin enhances neurofilament expression and neurite outgrowth in cultured rat cerebellar granule cells.
Somatostatin and its receptors are transiently expressed at a high level in the cerebellum around birth, before declining to adult levels by 2-3 weeks postnatally. We therefore investigated the neurotrophic effects of somatostatin (SS) on rat cerebellar granule cells in culture by measuring the percentage of cells with processes, the content of mRNA and protein for neurofilament (NF) and mRNA for glutaminase, and the number of viable cells (MTS assay). SS increased the percentage of cells with processes at 8 h after plating. After 1 day in vitro (DIV), SS caused a 2-fold increase in NF mRNA, and a 23% increase in NF protein. The mRNA increase was maximal at DIV1 whereas by DIV7 the NF protein content of control cells reached that of SS-treated cells. SS had no effect on glutaminase mRNA or on the number of viable neurons from either postnatal day 5 or 8 animals. These results demonstrated that SS has a neurotrophic effect on neurite production, including initiation of neurite outgrowth, but no effect on neuronal survival, cell proliferation, or phenotype differentiation (glutaminase expression), and support the possibility that SS plays a role in the differentiation of immature cerebellar granule cells during central nervous system development.
D000818:Animals; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology* / Q000187:drug effects; D004797:Enzyme-Linked Immunosorbent Assay; D009419:Nerve Tissue Proteins / Q000096:biosynthesis; D016501:Neurites / Q000187:drug effects*; D016900:Neurofilament Proteins / Q000096:biosynthesis*; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D013004:Somatostatin / Q000494:pharmacology*
D009419:Nerve Tissue Proteins; D016900:Neurofilament Proteins; D012333:RNA, Messenger; D013004:Somatostatin