The use of a tyrosine-hydroxylase cDNA probe to study the neurotransmitter plasticity of rat sympathetic neurons in culture.
We have compared quantitatively the effects of muscle-conditioned medium (CM) and elevated K+ concentration (40 mM) on the enzymatic activity of tyrosine hydroxylase (TH) and on TH-mRNA levels in primary cultures of rat sympathetic neurons. Northern blot analysis of RNA from cultured neurons with a 32P-labeled rat TH-cDNA probe was performed. The probe hybridized strongly with a single RNA species of 1.9 kb, similar in size to the TH-mRNA from PC12 pheochromocytoma cells. In agreement with earlier data both CM and a partially purified factor from CM increased choline acetyltransferase activity up to 200-fold and depressed TH activity by 2- to 7-fold in cultured sympathetic neurons. These effects were accompanied by a decrease in TH-mRNA level, which correlated with the decrease in TH activity. On the other hand, a culture medium supplemented with 40 mM KCl caused a 1.5- to 5-fold increase in TH activity, which was accompanied by an increase in TH-mRNA level of the same order of magnitude. As a working hypothesis, we suggest that CM and neuronal depolarization control the transcription of the TH gene in an antagonistic manner.
D000818:Animals; D002478:Cells, Cultured; D002795:Choline O-Acetyltransferase / Q000378:metabolism; D003470:Culture Media; D004247:DNA / Q000235:genetics; D005728:Ganglia, Sympathetic / Q000201:enzymology*; D005786:Gene Expression Regulation; D009132:Muscles / Q000502:physiology; D009474:Neurons / Q000187:drug effects / Q000201:enzymology*; D018377:Neurotransmitter Agents / Q000378:metabolism*; D009693:Nucleic Acid Hybridization; D010277:Parasympathomimetics / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D012964:Sodium / Q000494:pharmacology; D014446:Tyrosine 3-Monooxygenase / Q000235:genetics* / Q000378:metabolism
D003470:Culture Media; D018377:Neurotransmitter Agents; D010277:Parasympathomimetics; D012333:RNA, Messenger; D004247:DNA; D012964:Sodium; D014446:Tyrosine 3-Monooxygenase; D002795:Choline O-Acetyltransferase; D011188:Potassium