[Efficacy of antidepressants selected as a function of erythrocyte membrane transport and plasma levels of L-tyrosine and L-tryptophan]

The present study concerned 69 depressed patients (26 men, 43 women). The antidepressant drug was prescribed in accordance with perturbations of tyrosine and tryptophan membrane transports (MT) across the red cell, measured in vitro after a wash-out period of ten days. After two to four months of treatment, the clinical results were divided into two groups: normal mood (AMDP - Depression Scale less than 6) and no recovery (AMDP - Depression Scale greater than 6). The initial criteria (e.g. MT) was completed by using plasma tyrosine, tryptophan and the product MT by plasma level. Indeed, the success of this treatment was corresponding to precise abnormalities of variable: (i) tyrosine and tryptophan values for imipramine, (ii) tyrosine values, plasma tryptophan and tryptophan product for desipramine, (iii) tryptophan variables and plasma tyrosine for fluvoxamine (and indalpine). The analysis of clinical failures permitted to complete our previous choice of antidepressant drug.

[Erythrocyte membrane transport and plasma levels of tyrosine and tryptophan in depression]

L-Tyrosine and L-Tryptophan were studied in 80 depressed patients, hospitalised in Genova and Marseille. After a washout period of ten days, the erythrocyte membrane transports (MT) of L-Tyrosine and L-Tryptophan were measured, as well as their plasma levels; plasma phenylalanine was moreover measured. 33 normal subjects served as control group. In the whole population of patients, the mean of MT's was different compared to controls (MT tyrosine low and MT tryptophan high) and the plasma tyrosine was low. The perturbations of these variables were different according to diagnostic groups (DSM III): MT tyrosine, plasma tyrosine and tryptophan low in bipolar disorders depressed; MT tyrosine low, MT tryptophan high, plasma tryptophan low in major depressions; MT tryptophan high in dysthymic disorders. Phenylalanine was in the normal range compared to controls. The perturbations of MT's involved the part incubated at 37 degrees C for tyrosine, e.g. the facilitated diffusion, and the part incubated at 0 degrees C for tryptophan, e.g. probably the passive and facilitated diffusion. These results were in agreement with the monoaminergic hypothesis of affective disorders and might provide a useful peripheral model.

Sleep pharmacology of typical and atypical ligands of benzodiazepine receptors

The effects of several benzodiazepine and non-benzodiazepine ligands of benzodiazepine receptors have been investigated in sleep of normal young adults. The spectrum of activity of each compound has been characterized using a number of sleep variables in addition to the standard sleep stages. These substances affect all the principal components of sleep, that is the sleep-wake balance, paradoxical sleep, orthodox sleep and the EEG waveforms in the different sleep stages. Some, but not all, modifications induced by flunitrazepam are antagonized by flumazenil and they recover with various time constants after a single administration of the drug. The results of these experiments indicate a heterogeneity in the mechanism of action of benzodiazepine and non-benzodiazepine ligands of benzodiazepine receptors, because they affect differently the various components of sleep. It is not necessary to invoke a heterogeneity of the central benzodiazepine receptors (the BZ1-BZ2 theory) in order to account for these differences, but they can be explained by the concept of spare receptors.

[Relationship between blood catecholaminergic variables in depressive patients and normal subjects]

Some biochemical assays are available to test the central NA activity in depressed patients. In several laboratories, two metabolites of NA, namely DHPG and MHPG, in either free, conjugated or total form, have been assayed indifferently for this purpose. The present report shows positive correlations between the level of the two glycols, as well as between their different forms in the plasma. In contrast, the level of erythrocyte COMT activity was not correlated with plasma MHPG, and did not show any change during the treatment with respect to the control pretreatment period in depressed patients. The values of MHPG showed a bimodal distribution in the patients before treatment; the plasma level of this metabolite decreased significantly in the first month of treatment, but did not change subsequently. The COMT activity values, as well as MHPG, were significantly correlated between the different time points, that is the control period and after 1 to 3 months of treatment.

[Joint evolution of erythrocyte membrane transport of tyrosine and tryptophan as a function of the clinical course of depression]

The clinical state and the erythrocyte membrane transports of tyrosine and tryptophan were studied longitudinally during one year (minimum period of 3 months) in 44 depressive patients, 21 men and 23 women of 30 to 77 years of age. According to the DSM III, 18 patients had bipolar disorders (8 with short cycles), 14 had recurrent major depressions and 12 dysthymic disorders. Abnormal values for the membrane transports are found in the majority of patients; the pattern of these abnormalities differs among the nosological groups but decreased ratio of the tyrosine to tryptophan is the predominant finding. The membrane transports normalize as the clinical status improves. In bipolar disorders, the changes observed at the time of switching into mania differ among short and long cyclers. Short cyclers who become manic generally present a short period of normal mood and show values of membrane transports higher than when depressed or euthymic and higher than those of normal controls. Long cyclers directly switch into mania, and when manic have the same ratio of tyrosine to tryptophan than when depressed. Based on these biochemical observations, long cyclers resemble patients with recurrent major depression and short cyclers resemble dysthymic disorder patients, a group for which it has been suggested that one fifth become bipolar within years of evolution.

Evolution of red blood cell membrane transport and plasma level of L-tyrosine and L-tryptophan in depressed treated patients according to clinical improvement

The erythrocyte membrane transport (MT) of L-tyrosine (TYR) and L-tryptophan (TRP) and their plasma concentration showed abnormal mean values in 37 depressed patients compared to control subjects before treatment. The pattern of these abnormal values differed according to the clinical subgroup (DSM III criteria). In bipolar disorders the TYR values were all low and the TRP values showed little change, except a low level of plasma TRP. In major depression, MT were abnormal (MT TYR low, MT TRP high) with a very low plasma TRP. In dysthymic disorders the TYR and TRP values were normal. The normalization of the above biochemical variables was significantly correlated with the clinical improvement; however, the plasma concentration of TRP remained abnormal in some patients who had recovered. In contrast, only plasma TYR and TRP were significantly increased in patients without recovery.

The decrease of erythrocyte catechol-O-methyltransferase activity in depressed patients and its diagnostic significance

Erythrocyte catechol-O-methyltransferase (COMT) activity was measured in normal and depressed populations before specific medication. In the groups of patients, anxiety and depression scores were evaluated by the AMDP rating scale. The authors found lower enzyme activity in patients with major depression, recurrent and bipolar disorder, depressed, but no change was found in dysthymic disorder when compared to control values. However, there was no relationship between COMT activity and age, anxiety and depression scores of patients. Furthermore, the subdivision into two subpopulations, one with normal COMT activity and another with lower COMT activity, did not make it possible to assign a role to the enzyme in the severity of depression. The enzyme could, however, be considered as a genetic marker of depressive vulnerability.

[Topographic aspects of visual and auditory evoked potentials in schizophrenics]

The EPs to bilaterally presented non-verbal and non-cognitive visual and auditory stimuli were studied in 15 schizophrenics and 15 normal subjects. Many anomalies of exogenous components of VEPs and AEPs were observed in schizophrenics in comparison with control subjects, pointing to an abnormal cerebral functioning. So, the patients presented: (1) a less interhemispheric difference in latency of P100 component of VEPs over the occipital area; (2) a decrease or a lack of left hemispheric predominance of P2 component of AEPs over the central area; (3) a lower interhemispheric waveform similarity both for VEPs and AEPs. These results suggest a lower hemispheric specialization and interhemispheric synchronization of EPs in schizophrenics.

Determination of 3,4-dihydroxyphenylglycol (DHPG) by HPLC with coulometric detection, and correlation with 3-methoxy-4-hydroxyphenylglycol (MHPG) in human plasma

A method for determining plasma 3,4-dihydroxyphenylethyleneglycol (DHPG), a central noradrenaline (NA) metabolite, is described. The method used HPLC with dual coulometric detection set in screen mode of operation. The isolation of DHPG and related catecholamines (noradrenaline, dopamine and dihydroxybenzylamine) was performed on acid washed alumina extracted with 0.2 M HCIO4 containing EDTA (0.2%), and reduced glutathione as stabilizer. A reversed phase column with an eluting system containing 0.025 M citric acid-sodium hydrogen phosphate buffer in the ratio 3:2 (v:v) and 5% methanol was used. The experimental results of plasma DHPG levels compared favourably with the results from the literature, and a positively significant correlation with plasma MHPG was found. This method could be used as an alternative in central NA assessment.

In vitro effects of short-chain aliphatic alcohols, benzyl alcohol and chlorpromazine on the transport of precursors of monoamines across the human erythrocyte membrane

In previous papers we reported a deficit of tyrosine (TYR) and tryptophan (TRP) transport across the erythrocyte membrane in depressed patients. To investigate further the transport mechanism of both monoamine precursors, we tested in healthy subjects the role played by membrane fluidity, using different fluidizing agents such as alcohols and the neuroleptic chlorpromazine. We found that the transport of both amino acids depended on the length of the chain of each alcohol tested (number of carbon atoms = C). No inhibition was observed after methanol (C1) preincubation, in contrast to benzyl alcohol (C6), which produced an inhibition of about 80% of amino acid basal transport. In a condition of incubation by suspension of cells in an artificial medium, we observed a dose response of these transports with ethanol used at doses of 0.1-1.3 M. Finally we found in this study that the effect of ethanol on membrane fluidity, and therefore on inhibition of basal amino acid transport, was totally reversible after having washed the suspended cells, suggesting a superficial, noncovalent ethanol binding on such biological membranes.

EEG fitting: a new method for numerical analysis of EEG

A new method for numerical analysis of EEG is described. It consists of fitting the EEG with orthogonal polynomials in several steps to separate the different frequencies contained in the original recording (high-frequency noise, beta, sigma, alpha, theta, delta, low-frequency noise). The original EEG is separated into 5 different signals with cutoff frequencies at 40, 18, 4 and 0.6 Hz. The activity in these signals is classified into the usual EEG bands by zero-crossing. The results are given as integrated values over 1 s in the different EEG bands, or wave by wave, each wave being described by its time of occurrence, amplitude and duration. This method is designed for accurate amplitude measurement in the frequency bands of EEG, particularly for application in psychiatry and psychophysiology.

Internal structure of sleep cycles in a healthy population

A large body of data has been gathered on the sleep characteristics of normal subjects. The evolution of each sleep stage within each NREM/REM cycle is presented in detail, showing stage intensities minute by minute. There is a three-phase pattern in each stage intensity diagram: an initial phase of rapid change; a central phase of relative stability; and a terminating phase, again, of rapid change. The details of this pattern change progressively during the night. Throughout all cycles, there is a complementary relationship between the intensities of stage 2 sleep and the other stages that underlines the central role of stage 2 sleep in all stage transitions. Stage intensity diagrams for two groups, one group with and one group without stage 4 sleep, were compared. Subjects without stage 4 sleep tended to have a shorter duration and greater latency of stage 3 sleep. Surprisingly, cycles interrupted by abnormally long periods of continuous wake showed a negative correlation between the intensities of wake and slow wave sleep, and these interruptions did not appear to reset the cycle clock to zero. Sleep stage intensity diagrams may be useful to study the sleep patterns of populations of insomniac and depressive patients, as well as the effect of drugs on sleep.

A biometric study of three populations of the European grayling, Thymallus thymallus (L.), from the French Jura Mountains

Three populations of grayling (Thymallus thymallus L.) from the Jura Mountains (Rhône drainage basin, France) were compared using 8 meristic and 10 morphometric characteristics; discriminant analysis clearly distinguished these populations. This result raises a number of questions about the specificity of fish populations inhabiting any given river and the usefulness of stocking that has been carried out up to now without any controls.

[Sleep in Pick disease]

19 polygraphic sleep recordings from 12 patients with Pick's Disease, including four histologically proved cases, were compared to those of an age-matched control group. Symptoms had been present for a mean 8 years, the patients being aged 59 to 78 (mean 70.5 years). All sleep stages could be identified. Total sleep time was reduced and the number of awakenings was sharply increased. High proportion of stage 1 contrasted with the reduction in the other sleep stages with disappearance of stage 4 in advanced cases. REM Sleep was identified in all recordings, although reduced as a function of the length of the illness; its production as a function of total sleep time was not different from that of the control. REM Sleep appeared often fragmented and with a remarkably short latency, reminiscent of that observed in severely depressed patients.

Is 3,4-dihydroxyphenylglycol the major route of central norepinephrine metabolism in rat brain?

Central norepinephrine (NE) metabolism was assessed by measuring 3-methoxy-4-hydroxyphenylethyleneglycol (MHPG) and 3,4-dihydroxyphenylethyleneglycol (DHPG) in different rat brain areas after saline or probenecid (300 mg/kg) administration. Under probenecid, results showed an increased accumulation of total MHPG and DHPG, and a clear preponderance of DHPG levels over MHPG in almost all the brain areas examined. Estimation of their formation rates confirmed that in basal conditions DHPG is formed more rapidly. This study supports the notion that, without ruling out the importance of MHPG, brain DHPG may be a useful index of central NE activity.

[Choice of antidepressive agents as a function of membrane transport (erythrocytes) of monoamine precursors (L-tyrosine and L-tryptophan)]

In a group of 66 depressed patients, the choice of the antidepressant drug was based upon the result of tyrosine and tryptophan uptake by the membrane of red blood cells. After one month of treatment, 56 subjects were improved, that is 85% of the cases. This result is discussed in comparison with the percentage of improvement described in the literature.

[Erythrocyte membrane transport of L-tyrosine and L-tryptophan in 66 patients with depressive syndromes. Preliminary results]

The transport of Tyrosine and Tryptophan by the membrane of red blood cells has been studied in a group of 66 depressed patients (DSM-III: 27 major depressions, single episode or recurrent; 17 bipolar disorders, depressed; 22 dysthymic disorders). Anomalies were observed: tyrosine transport was decreased in the bipolar disorders and in the major depressions; tryptophan transport was increased in the major depressions and in the dysthymic disorders. These results suggest that membrane transports are disturbed in depressed syndromes, and may be related to dysfunction in the monoaminergic balance.

In vitro effects of ionophores and inhibitors of main sodium and calcium movements on tyrosine and tryptophan transport by human erythrocytes

Peripheral models using blood cells might be biochemical markers in various psychiatric illnesses. In previous papers we reported a deficit of tyrosine and tryptophan transport in red cells incubated in plasma from depressed patients. In the present study we investigated the role played by sodium and calcium in these transports by using inhibitors and ionophores of the main movements of these electrolytes. We also studied the contribution of phloretin-sensitive countertransport, which has been described as low in psychiatric conditions.

L-tyrosine and L-tryptophan transport in red blood cells in normal subjects. Effects of other amino acids, temperature and medium of incubation

Blood cells may be used as a model in the central transport mechanisms of amino acids, precursors of amines, implicated in some hypotheses of psychiatric diseases. In a previous paper, we showed a deficit of tyrosine transport by red cells incubated in the plasma of depressed patients. In the present study, we have investigated the interaction of these peripheral transport mechanisms for tyrosine and tryptophan with other amino acid transports, such as the L and ASC systems, and the role of sodium ions in the extracellular medium. We also describe the inhibition induced by incubation at a low temperature, and a probable role of the membrane viscosity. The interest of incubating the cells in their own plasma, in order to have physiological conditions, is also discussed.

Modifications of sleep parameters in the rat by (+)- and (-)-3-PPP

The effects of subcutaneous administration of the two enantiomers of 3-(3-hydroxyphenyl)-N-n-propylpiperidine (3-PPP), a new dopamine analogue, were studied with regard to their effects on sleep parameters in the rat. The studies with both enantiomers were carried out taking into account their different effects on central dopaminergic receptors. At low doses they act preferentially as autoreceptor agonists; at higher doses the (+)-form is also an agonist while the (-)-form acts as an antagonist at postsynaptic dopamine receptors. The results showed the following: (1) with the high dose of (+)-3-PPP there was no change in REM sleep, but a marked increase in wakefulness; (2) with the high dose of (-)-3-PPP there was a significant increase in REM sleep and in the mean duration of REM episodes; (3) with the low dose of (+)-3-PPP similar results to those described for high-dose (-)-3-PPP were obtained; (4) there was no significant alteration of sleep parameters with the low dose of (-)-3-PPP. The data are discussed in terms of an active role for dopamine in the regulation of REM sleep.

Statistical description and evaluation of the interrelationships of standard sleep variables for normal subjects

This study explores the relationships between the standard sleep variables, particularly between those of NREM and REM sleep. A total of 399 nights of sleep was recorded in 147 adults who had no known pathology. This amount of data allowed for an accurate description of the generally nonnormal variable distributions and established the relative predominance of the intra- over the interindividual variability. Most correlations between variables were low, showing that there is little redundancy in the choice of variables. The relationships between stage 2 and 4 of NREM and REM sleep and between sleep stages and wakefulness were statistically significant. We found that a short latency of stage 2 predicted a sleep of poorer quality than did a longer latency and confirmed that stage 2 has a central role in transition between stages. Finally, there was an association between the variables describing sleep stability and those describing cyclic organization and sleep efficiency. However, it cannot be determined from these data whether teh relationship is causaL or permissive. In addition, these results suggest that further work on cycle structure is required and that future experiments should incorporate a larger number of observed nights per individual.

Brain noradrenergic activity in wakefulness and paradoxical sleep: the effect of clonidine

Several experiments in which the effects of clonidine (CLN) have been studied in the rat and in man are summarized. CLN inhibits paradoxical sleep (PS) both in the rat and in man. This inhibition is followed by a rebound, but with a different time course in the two species. Wakefulness (W) is enhanced after some critical doses of CLN, and decreased after higher doses. These effects of CLN suggest that alpha 2-adrenoceptors are involved in the regulation of W and PS.