Topographical distribution of dopaminergic innervation and dopaminergic receptors of the anterior cerebral cortex of the rat.

The quantitative topographical distribution of the dopaminergic innervation and the DA-sensitive adenylate cyclase were estimated in the anterior cerebral cortex of the rat. The high affinity uptake of [3H]DA and endogenous levels of DA were used as markers of the dopaminergic innervation. [3H]DA uptake, DA levels and DA-sensitive adenylate cyclase were estimated in microdiscs of tissues punched out from frozen serial frontal slices.

[Lack of participation of cytoplasmic choline in the synthesis of acetylcholine in the striatal synaptosomes of the rat].

Synaptosomes prepared from Rat striatum were loaded with (14C) choline at 0 degrees C in the course of a 60 min. preincubation. After the removal, by washing, of the extracellular molecules, synaptosomes were incubated 5 min.

Release of dopamine in both caudate nuclei and both substantia nigrae in response to unilateral stimulation of cerebellar nuclei in the cat.

The effects of unilateral focal electrical stimulation of the deep cerebellar nuclei on the activity of the nigrostriatal dopaminergic neurons on both sides of the brain were examined in halothane anaesthetized cats. For this purpose, push-pull cannulae were inserted into both caudate nuclei and both substantia nigrae, and the release of [3H] dopamine ([3H]DA) continuously formed from [3,5-3H]L-tyrosine was estimated in superfusates. The unilateral electrical stimulation of the right cerebellar dentate nucleus induced a long-lasting increase in the release of [3H]DA in the left caudate nucleus and a simultaneous decrease in the release of [3H]transmitter in the right caudate nucleus.

Dopamine uptake in serotoninergic terminals in vitro: a valuable tool for the histochemical differentiation of catecholaminergic and serotoninergic terminals in rat cerebral structures.

An in vitro method was developed to separately visualize dopaminergic, noradrenergic and serotoninergic terminals in the cerebral, hippocampal and cerebellar cortices of the rat, by means of the glyoxylic histochemical fluorescence method. Animals were pretreated with alpha-methylparatyrosine to deplete catecholamine stores. Thin vibratome sections were made and incubated in the presence of various exogenous amines and inhibitors of the catecholaminergic and serotoninergic transport systems.

Paradoxical decrease of brain 5-HT turnover by metergoline, a central 5-HT receptor blocker.

Since metergoline (1-methyl-8-beta-carbobenzyloxy-aminomethyl-10-alpha-ergoline) is a potent 5-HT antagonist in peripheral organs, its possible blocking effects on 5-HT receptors in the rat brain were investigated. In vitro, metergoline inhibited both the specific high affinity binding of 3-H-5-HT onto synaptosomal membranes (IC 50 = 18 nM) and the stimulating effect of 10 micron 5-HT on the adenylate cyclase activity in colliculi homogenates from newborn rats (IC 50 = 12 micron. In vivo, the administration of metergoline (10 mg/kg i.

Release of dopamine evoked by electrical stimulation of the motor and visual areas of the cerebral cortex in both caudate nuclei and in the substantia nigra in the cat.

The effects of unilateral stimulation of the cerebral motor cortex and of the visual cortical area on the activity of the nigrostriatal dopaminergic neurons were examined in halothane-anesthetized cats. For this purpose, one push-pull cannula was inserted in each caudate nuclei and another one in the substantia nigra ipsilateral to the stimulated side. In all cases, the release of [3H]dopamine ([3H]DA) continuously formed from L-[3,5-3H]tyrosine was estimated in superfusates.

[Arguments in favor of the extramitochondrial origin of the acetyl radical of acetylcholine synthetized in rat striatum synaptosomes].

Synaptosomes prepared from Rat striatum were loaded with (2-14C) pyruvate at 0 degree C, in the course of a 1 hr. preincubation. When temperature was raised to 37 degrees C, the intra-synaptosomal (2-14C) pyruvate gave rise to 14CO2 but not to (14C) ACh.

Inhibition of dopamine release in the cat caudate nucleus by nigral application of glycine.

"Encéphale isolé" cats were implanted with two push-pull cannulae, one in the left caudate nucleus and the other in the ipsilateral substantia nigra. L-3,5(-3)H-Tyrosine was introduced continuously into the caudate nucleus to study the release of 3H-DA. Glycine (10(-5)M) added to the superfusing medium of the push-pull cannula inserted into the substantia nigra reduced (25%) the spontaneous release of 3H-DA.

Regional differences in the sensitivity of cholinergic neurons to dopaminergic drugs and quipazine in the rat striatum.

Marked differences were found in the activity of choline acetylase (ChAc) in various discrete areas of the rat striatum. The richest cholinergic innervation was observed in the centrolateral part of the structure. A similar distribution was obtained by measuring acetycholine (ACh) levels in punches taken from frozen frontal serial slices.