Francoise Garcin

Biological markers in major psychosis and alcoholism: Phenotypic and genotypic markers

Some basic concepts and trends which appear to be essential in the search for biological markers in mental disorders are discussed. Comments related to major psychosis and alcoholism are presented under three headings: (i) heterogeneity of disorders (ii) multifactoriality of disorders and (iii) mental disorders as genetically influenced disorders. Tentative classification and terminology of biological markers are given. Various types of phenotypic markers are discussed and alcoholism is taken as a model for a more detailed discussion of available putative phenotypic markers and of research strategies to be used, namely the pharmacological challenge in high risk subjects (e.g. ethanol and TRH challenge). Some highlights from the field of DNA markers are described, mainly the basic procedures which may be used to investigate genetic aspects of mental disorders by recombinant DNA technology.

Acetaldehyde oxidation in Drosophila melanogaster and Drosophila simulans: Evidence for the presence of an NAD+-dependent dehydrogenase

Abstract 1. 1. An NAD+-dependent oxidation of acetaldehyde has been found in two Drosophila species, D. melanogaster and D. simulans. 2. 2. The enzymatic activity was assessed in partially purified preparations from fly homogenates by monitoring spectrophotometrically NADH production at 340 nm at 25°C. 3. 3. Optimal activity was observed at pH values between 10 and 11 for both species. 4. 4. For both species the affinities ( K m ) for acetaldehyde were in the micromolar range whereas those for NAD+ were in the 100 μM range. 5. 5. Catalytic activity ( V max ) was 2-fold higher in D. melanogaster, a species with high tolerance to ethanol, than in D. simulans, a species with a much lower tolerance to ethanol. 6. 6. Disulfiram proved to inhibit NADH production in preparations of both species. 7. 7. It is concluded that the enzyme involved is an NAD+-dependent aldehyde dehydrogenase (ALDH). Its possible biological significance in ethanol tolerance is discussed.

Experimental narcotic dependence models of primary dependence, abstinence and relapse obtained by intravenous self-administration in rat

Abstract 1. 1. This study evaluated the usefulness of two animal models of morphine dependence, one based on intravenous voluntary self-administration and the other an automated or forced infusion model. 2. 2. The pattern of self-administration observed during primary dependence development in drug-naive rats stabilized after about 14 days with a daily drug intake of 240 mg/kg. 3. 3. On the basis of the self-administration data, a 6-day accelerated model of primary dependence has been produced by passive, automatic administration. In these conditions, animals displayed a similar degree of physical dependence to that observed with self-administration. 4. 4. A triphasic abstinence period is described. The duration, symptoms and propensity to relapse are analysed for each of the three phases: early, intermediate and protracted. 5. 5. The secondary dependence or relapse data obtained in ex-addicted rats allowed to re-administer morphine showed that in comparison with the primary dependence, a higher drug intake was sustained when tested at fixed inter vals between one and six months following morphine removal. 6. 6. Naloxone administered before and in association with morphine during a 7-day period blocked morphine self-administration. This effect was more potent in preventing secondary dependence in ex-addicted animals than the pri mary dependence in drug-naive animals.

Acetaldehyde oxidation inDrosophila null-mutants for alcohol dehydrogenase

Aldehyde dehydrogenase (ALDH) activity is demonstrated in four strains ofD. melanogaster lacking active alcohol dehydrogenase (ADH-null mutants). In the four strains, ALDH activities are similar to those found in a wild strain. It is concluded that ADH-null flies are able to detoxify acetaldehyde. This finding is discussed in relation with the dual function of ADH proposed recently.

Double blind study on the efficacy and safety of tetrabamate and chlordiazepoxide in the treatment of the acute alcohol withdrawal syndrome

1. Efficacy and safety of tetrabamate and chlordiazepoxide in the treatment of the acute or Primary Alcohol Withdrawal Syndrome (PAWS) were assessed during a randomized double blind clinical trial, carried out on sixty male alcoholic in-patients. 2. The two drugs were administered four times a day in double dummy conditions, according to a fixed-flexible decreasing dosage schedule (six days basic regimen). 3. Drug efficacy was measured daily throughout the study period using a battery of standard instruments for collecting quantitative clinical, behavioral, psychopathological and laboratory data. Side effects were daily recorded. 4. Tetrabamate was found to be as efficient as chlordiazepoxide in reducing the intensity of the PAWS, improving sleep and vital signs rapidly and alleviating anxiety progressively. 5. Tetrabamate was found particularly beneficial for severe tremor. Psychomotor and mood scores consistently favored tetrabamate, suggesting psychoanaleptic properties of this compound (increased diurnal vigilance). 6. Side effects were minimal with tetrabamate and generally of weak intensity with chlordiazepoxide. 7. The results of this study indicate that tetrabamate may represent a new alternative drug of choice for the therapy of the acute alcohol withdrawal syndrome.

Aldehyde dehydrogenase in drosophila: Developmental and functional aspects

Alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) activities were determined in adult flies from several Drosophila species endowed with widely different tolerance to ethanol (ETOH). Plotting ALDH against ADH activities resulted in a high correlation coefficient (r = 0.966). This finding was confirmed in developmental studies. From early larval stage up to late adult life, ADH and ALDH activities demonstrated almost parallel profiles. In the highly ETOH tolerant species D. melanogaster (D.m.), ADH and ALDH profiles were U-shaped: high activities in larvae, low activities in pupae and high activities in adults. In D. simulans (D.s.), a species less tolerant to ETOH, the profiles were L-shaped: high activities in larvae but low activities in both pupae and adults. Interestingly, similar activities (ADH and ALDH) were observed in the larvae of both species. Subcellular distribution studies of larval ALDH in both species revealed that the total ALDH activity is largely contributed by a mitochondrial high affinity enzyme. ALDH activity, clearly distinguishable from aldehyde oxidase (ALDOX), was visualized through analytical isoelectric focusing of the subcellular fractions. The estimated pIs for D.m. and D.s. were 4.9 and 5.2 respectively, thus different from those of ADH. The key biological role initially attributed to Drosophila ALDH is further supported by the present data. In addition the Drosophila developmental model opens new avenues for research on the study of genetic regulation of ADH and ALDH expression.

NAD+-dependent acetaldehyde oxidation in Drosophila☆

Abstract 1. 1. NAD + -dependent acetaldehyde oxidation was measured spectrophotometrically in homogenates of flies Drosophila melanogaster. 2. 2. The reaction was specifically triggered by addition of acetaldehyde and proceeded linearily over five minutes. 3. 3. At low acetaldehyde concentrations the reaction rate was rapidly maximal whereas higher acetaldehyde concentrations proved to be inhibitary. 4. 4. Enzyme activity in regard to NAD + concentration followed classical Michaelis kinetics. The apparent Km for NAD + was 0.05 mM. 5. 5. These data provide evidence for the presence of a NAD + -dependent aldehyde dehydrogenase. It is suggested that this enzyme is involved in the oxidation of acetaldehyde in Drosophila. 6. 6. The biochemical and biological significance of this enzyme in regard to ethanol metabolism and ethanol tolerance is discussed.

Genetic epidemiology and the prevention of functional mental disorders and alcoholism: Family study and biological predictors

1. This review intends to present some theoretical and practical considerations which appear essential for the development of rational research strategies in the field of primary and secondary prevention of mental disorders and alcoholism. 2. The various advances and trends regarding the nosology and diagnosis of these disorders are discussed. Integrative epidemiological models for relating the multifactorial causation and the heterogeneity (multidimensionality) of these disorders are presented. 3. It is emphasized that alcoholism and the functional mental disorders occur in families as shown by (i) the increased incidence of these disorders among relatives and (ii) the existence of various clinical categories genetically associated. 4. Current methodology in clinical diagnosis and genetic epidemiology represent powerful procedures for typing and subtyping of these disorders. Family studies could identify more homogeneous subgroups and generate hypotheses as to the mode of transmission of mental disorders and alcoholism. 5. Real progress could be made in prevention only if the search for predictors is carried out in homogeneous subgroups. 6. There is a lack of knowledge regarding biological predictors. An urgent need for association studies and linkage analysis should be carried out in order to identify genetic markers (causal relationship) and chromosomal markers. These could provide for the specification of a constellation of markers and the development of appropriate tests to identify subjects at risk likely to develop alcoholism and mental disorders. 7. The immediate issues in secondary prevention and the later outcomes in primary prevention are outlined.

EXPERIMENTAL PHARMACODEPENDENCE. OPIATE AND AMPHETAMINE INTRAVENOUS SELF-ADMINISTRATION ANIMAL MODELS

Abstract 1 Animal intravenous self-administration models of narcotic and CNS stimulant dependence, using morphine and d-amphetamine respectively as prototypes, are being investigated as fundamental research instruments within experimental and clinical neuro-psychopharmacology. 2 The pattern of primary dependence on morphine obtained in drug-naive rats by self-administration, showed that daily morphine intake stabilized after about 2 weeks of unlimited drug access. A new 6-day accelerated program has been developed using automatic i.v. administration, which replicates major dependence characteristics of the slower self-administration paradigm. 3 A triphasic abstinence pattern was observed after morphine removal. This pattern consisted of an early (acute), transitional (subacute) and protracted phase. 4 The relapse or secondary dependence data obtained in ex-addicted rats showed a higher morphine intake than in primary dependence tests which was still significant 6 months after forced abstinence. 5 Two patterns of intravenous self-administration of d-amphetamine were described in rats: a poly cyclic pattern and a sequential cyclic/non-cyclic pattern which were obtained respectively after unlimited (24 hr/day) and combined unlimited/limited (6 hr/day) drug access. 6 On the basis of its low neurotoxicity, the two-component sequential model appears suitable for long-term behavioural and molecular pharmacology studies.

PHARMACOGENETIC APPROACH OF THE EFFECT OF MORPHINE AND ALCOHOL IN MICE

Abstract Several inbred strains of mice were used as experimental model for the approach of the role of genetic factors in the sensitivity to psychoactive drugs. The comparison of the effect of increasing doses of morphine in five strains of mice demonstrates that the locomotor response of mice is a biphasic, hypo-hyperkinetic one. Strain differences concern mainly the pattern of the hyperkinetic phase. They are compared to strain differences in adrenergic reactivity and in apparent number of naloxone binding sites and affinity. On the other hand, cross tolerance between alcohol and morphine is demonstrated to occur and to be genetically determined.