Short-term lithium administration to healthy volunteers produces long-lasting pronounced changes in platelet serotonin uptake but not imipramine binding.

Platelet [3H]-5HT uptake, [3H]-imipramine binding and endogenous 5HT levels were measured in healthy volunteers during short-term (20 days) administration of lithium, and following its withdrawal. The Vmax of [3H]-5HT uptake was significantly decreased during lithium treatment. Following lithium withdrawal, platelet [3H]-5HT uptake (Vmax) remained decreased and was followed by a pronounced rebound effect in some of the subjects for up to 3 months.

Changes in human platelet 5 HT level after 1 week of chlorimipramine treatment.

In platelets of six volunteers taking chlorimipramine (50 mg/day) for 1 week, 5-HT levels were markedly decreased at the time of treatment withdrawal, and remained significantly reduced after a 1-week washout. Individual levels in five subjects remained affected during a 3-week washout. The previously reported observations of reduced serotonin concentration in platelets from depressed patients may reflect a residual effect of previous antidepressant treatment.

Platelet serotonin in essential hypertension and in mental depression.

The similarity between the metabolic pathways of serotonin in platelets and serotoninergic nerve endings has often been emphasized. The turnover of serotonin was therefore investigated in two diseases: hypertension (as central serotoninergic neurones appear to modulate central sympathetic nervous activity) and depression (as a central 5-HT-deficiency and a low 3H-imipramine binding on platelets have been described in patients with endogenous depression). Mean platelet 5-HT level was significantly lower in essential hypertensives than in controls.

Reduced platelet serotonin in depression.

Platelet serotonin levels were measured in several psychiatric disorders to determine whether they distinguish among major depressive disorder (one or more depressive episodes and no manic episodes), dysthymic disorder (depressive neurosis), and schizophrenic and paranoid disorders. Serotonin levels in 141 subjects were determined using high performance liquid chromatography with electrochemical detection. Serotonin (5HT) levels in control subjects were significantly lower in males than in females.

Decreased uptake of 3H-serotonin and endogenous content of serotonin in blood platelets in hypertensive patients.

The uptake and content of serotonin in blood platelets were studied in patients with essential hypertension and in five families in which at least one member was hypertensive. Blood was obtained from male and female normotensive volunteers and hypertensive patients who were free of medication. Lineweaver-Burk plots of 3H-serotonin uptake from both control subjects and hypertensive patients were linear, which suggested simple Michaelis-Menten uptake kinetics.

Nomifensine antagonizes the ouabain-induced increase in dopamine metabolites in cerebrospinal fluid of the rat.

The effect of the Na+, K+-ATPase inhibitor, ouabain, on cerebrospinal fluid dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA) and 5-hydroxyindolacetic acid (5-HIAA) levels was studied in pentobarbitone-anesthetized rats. An intracerebroventricular injection of ouabain (100 nmol) dramatically increased DOPAC and HVA levels. A dopamine uptake inhibitor, nomifensine (10 mg/kg i.

Probenecid sensitive pathway of elimination of dopamine and serotonin metabolites in CSF of the rat.

CSF was removed at a constant flow rate of 1 microliter/min from the third ventricle of anesthetized rats. Five microliter CSF samples were directly injected every 15 min into a liquid chromatographic system coupled with an amperometric detector. Mean CSF values for free dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA) and 5-hydroxyindolacetic acid (5-HIAA) were 1.

Central administration of yohimbine increases free 3-methoxy-4-hydroxyphenylglycol in the cerebrospinal fluid of the rat.

The effect of the alpha2-antagonist, yohimbine, on cerebrospinal fluid 3-methoxy-4-hydroxyphenylglycol (MHPG), dihydroxyphenylacetic acid (DOPAC), and 5-hydroxyindolactic acid (5-HIAA) concentrations was studied in vivo. Cerebrospinal fluid was removed at a constant flow rate of 1 microliters/min from the third ventricle of rats and directly analysed by liquid chromatography coupled with electrochemical detection. An intracerebroventricular injection of yohimbine (100 nmol) dramatically increased MHPG levels.

Rapid liquid chromatographic determination of 5-hydroxyindoles and dihydroxyphenylacetic acid in cerebrospinal fluid of the rat.

A stainless steel guide was implanted in the anterior third ventricle of the anesthetized rat and an internal needle shorter than the guide was used to continuously collect cerebrospinal fluid (CSF) at a constant outflow of 1 microliter/min. Five microliter samples were injected directly into a liquid chromatographic column. The mobile phase was adjusted for selective separation of 5-hydroxytryptophan (5-HTP), serotonin (5-HT), dihydroxyphenylacetic acid (DOPAC) and 5-hydroxyindolacetic acid (5-HIAA).

[Inhibitory effect of noradrenaline on dopamine release from the hypothalamus of the rat].

1. The release of dopamine from the anterior hypothalamic/preoptic region of the anesthetized and artificially ventilated rats was investigated in vivo using a superfusion technique with a push-pull cannula. L-DOPA and pargyline were added to synthetic cerebrospinal fluid superfusing the area.

[Implication of anterior hypothalamic dopamine in the regulation of arterial pressure].

The anterior hypothalamus is essential for the normal carotid sinus baroreceptor reflex. The dopamine innervation to this region is a projection from the dopaminergic A 14 cell group of the rostral hypothalamus. The anterior hypothalamic/preoptic region (AH/PO) was unilaterally superfused with buffer containing L-DOPA (10(-4) M) and the superfusate analyzed for dopamine using liquid chromatography with electrochemical detection.

LCEC monitoring of 5-hydroxyindolic compounds in the cerebrospinal fluid of the rat related to sleep and feeding.

A new technique which allows for both the chronic withdrawal of CSF and continuous recording of EEG sleep patterns and food intake in the freely moving rat is described. Liquid chromatography with electrochemical detection (LCEC) was used for the direct assay of tryptophan metabolites in the CSF. Both 5-hydroxyindolacetic acid (5-HIAA) and 5-hydroxytryptophan (5-HTP) were easily detectable.

Alpha 1- and alpha 2-adrenoceptors in rat cerebral cortex: effects of neonatal treatment with 6-hydroxydopamine.

Neonatal 6-hydroxydopamine treatment was used to destroy the noradrenergic nerve terminals in rat cerebral cortex and thus give some insight into the in vivo regulation of alpha-adrenoceptor subtypes, which in turn provides information concerning the anatomical localization of alpha 1- and alpha 2-adrenoceptors. Treatment of rats in the neonatal period with 6-OHDA causes an irreversible decrease in noradrenaline levels of the cerebral cortex compared to controls. Differences in [3H]clonidine and [3H]prazosin binding in the cerebral cortex occurred which varied depending upon the time elapsed between denervation and the binding assay.

Regional distribution of noradrenaline and dopamine-beta-hydroxylase in the brain of spontaneously hypertensive rats.

The catecholamine concentration and dopamine-beta-hydroxylase activity were determined in several nuclei of the brain of spontaneously hypertensive rats (SHR) compared with Wistar Kyoto (WKY) controls. Catecholamines were measured by using liquid chromatography coupled with electrochemical detection. The threshold of detection was 5 X 10(-14) mole.

Effect of neonatal 6-hydroxydopamine treatment on alpha 1- and alpha 2-adrenoceptors in rat cerebral cortex.

Neonatal 6-hydroxydopamine (6-OHDA) treatment was used to destroy the noradrenergic nerve endings in rat cerebral cortex and thus give some insight into the development and regulation of alpha-adrenoceptor subtypes, which in turn provides information concerning the anatomical localization of alpha 1- and alpha 2-adrenoceptors. In cerebral cortex of rats treated in the neonatal period with 6-OHDA, we have observed an irreversible decrease in noradrenaline levels. Differences in 3H-clonidine and 3H-prazosin binding occurred which varied depending upon the time between denervation and the binding assay.

In vivo dopamine release from the anterior hypothalamus of the rat.

The release of dopamine from the anterior hypothalamic/preoptic region of the anesthetized rat was investigated in vivo using a superfusion technique with a push-pull cannula. Dopamine was measured electrochemically after separation by liquid chromatography. The spontaneous release of dopamine was very low but detectable in some experiments.

Distinguishing traits in the Sabra hypertension-prone (SBH) and hypertension-resistant (SBN) rats.

Distinct differences in central and peripheral noradrenaline (NA) were observed in the hypertension prone (SBH) and resistant (SBN) strain, derived from the Hebrew University SABRA rats. In the medulla oblongata NA concentration was 90% higher and tyrosine hydroxylase activity 88% lower in SBN when compared to SBH, suggesting marked strain differences in NA turnover. In this area, NA-induced cAMP generation was higher in SBH than in SBN, while the hypothalamus, the reverse situation was present.

Early changes in noradrenaline content of some brain nuclei in spontaneously hypertensive rats.

1. The noradrenaline content of individual brain nuclei was measured by using high-pressure liquid chromatography coupled with electrochemical detection. 2.

[Catecholamine determination in plasma using high performance liquid chromatography with electrochemical detection. Application to a rapid diagnosis of phaeochromocytoma (author's transl)].

The advantages of this technique are rapidity (performed in less than twenty minutes), reproductibilitky, and low cost. Chemical manipulation of plasma is unnecessary to diagnose phaeochromocytoma as shown in two examples. We propose therefore introduction of this technique in clinical investigation of hypertensive patients.