Choline and acetylcholine metabolism in slice cultures of the newborn rat septum.
The incorporation of [3H]choline into acetylcholine and other choline-containing compounds was investigated in slice cultures of the septal area of newborn rats. At choline concentrations in the range of the high affinity transport mechanism (0.1-1 microM) most of the labeled choline was incorporated into phosphorylcholine, followed by lipids, acetylcholine and the free choline pool. Hemicholinium-3 (1-10 microM) lead to a marked decrease of acetylcholine synthesis, whereas choline accumulation or phosphorylcholine synthesis were not decreased. Both basal and K+-induced release of acetylcholine were Ca2+ dependent. The efflux of choline was not stimulated by high K+. When choline was absent from the incubation medium, the slices were able to liberate significant amounts of the [3H]choline previously incorporated into phospholipids, and were also able to synthesize some acetylcholine. In choline-free medium, acetylcholine synthesis was greatly enhanced by depolarization. During the period in culture, there was a decrease of the incorporation rate of [3H]choline into phosphorylcholine and an increase of the incorporation rate into acetylcholine. The tissue structure was well preserved after several weeks in culture. After staining for acetylcholinesterase, the cholinergic neurons in the cultures showed a similar morphology to that seen in situ. The main conclusions of the present study are: cholinergic neurons in slice cultures develop and behave in a manner which is very similar to their in situ counterparts; the main divergence from previous studies of choline metabolism in tissue culture is the substantial incorporation rate of choline into acetylcholine at choline concentrations in the range of the high affinity uptake mechanism.(ABSTRACT TRUNCATED AT 250 WORDS)
D000109:Acetylcholine / Q000378:metabolism*; D000110:Acetylcholinesterase / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn / Q000378:metabolism*; D002478:Cells, Cultured; D002794:Choline / Q000378:metabolism*; D046508:Culture Techniques; D006426:Hemicholinium 3 / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012688:Septum Pellucidum / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*
D006426:Hemicholinium 3; D000110:Acetylcholinesterase; D002794:Choline; D000109:Acetylcholine; D011188:Potassium