Developmental changes in the synthesis of @entity934 ( @entity1617 ) were investigated in @entity35 hippocampus and frontal cortex. Particular reference was made to the conversion, into @entity1617 , of the @entity1877 accumulated by high-affinity uptake as defined using 1 microM @entity11348 (HC-3). Using solutions containing 11.1 mM @entity413 , conversions were respectively 31 and 55%, in fine slices from 4-8-day-olds. Free @entity1877 accounted very largely for the remainder of the @entity1877 accumulated. In samples from adults, @entity1617 accounted for 80% of the uptake. The inefficient conversions (into @entity1617 ) in immature brain were not the result of a requirement for @entity6178 bodies as the source of @entity6625 ( @entity6625 ). Greater rates of release of newly synthesised @entity1617 , than in mature samples, were not responsible, neither were greater cholinesterase activities. The stimulation of high-affinity @entity1877 uptake, caused by prior depolarisation of the tissues using K+, also increased during development from 78 to 238% with hippocampus and from 49 to 170% with frontal cortex. Furthermore, prior depolarisation increased the efficiency with which @entity1877 , accumulated by high-affinity uptake, was converted into @entity1617 . At all stages of development 80% of the additional @entity1877 accumulated, after depolarisation, was converted into @entity1617 . It is concluded that the specificity of HC-3-sensitive uptake is incomplete in immature brain, i.e. high-affinity @entity1877 uptake is not exclusively into cholinergic neurones. The cholinergic neuronal compartment becomes more prominent during development so that the specificity is complete in mature brain.(ABSTRACT TRUNCATED AT 250 WORDS)

High-affinity uptake of @entity1877 , a marker for cholinergic nerve terminals, is not specific in developing XXXX brain.

@entity1617 :: ('CHEBI:22614', 'Chemical') :: ['ACh'] @entity1877 :: ('MESH:D002794', 'Chemical') :: ['choline'] @entity6178 :: ('CHEBI:17087', 'Chemical') :: ['ketone'] @entity35 :: ('10116', 'Species') :: ['rat'] @entity11348 :: ('MESH:D006426', 'Chemical') :: ['hemicholinium-3'] @entity6625 :: ('MESH:D000105', 'Chemical') :: ['acetyl-CoA', 'acetyl-coenzyme A'] @entity413 :: ('MESH:D005947', 'Chemical') :: ['glucose'] @entity934 :: ('MESH:D000109', 'Chemical') :: ['acetylcholine']
@entity35 :: (10116,Species) :: ['rat']
