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The binding of [3H]3,4-methylenedioxymethamphetamine [( 3H]MDMA) to both rat brain membrane preparations and glass fiber filter papers was analyzed in the present study. Saturation studies indicate that [3H]MDMA binding is saturable and monophasic in both the presence and absence of rat brain membranes. This apparent 'specific' binding of [3H]MDMA in both the presence and absence of brain homogenates was totally eliminated by pretreating glass fiber filter papers with polyethylenimine. Drug competition studies demonstrated that [3H]MDMA binding displays a distinct 'pharmacological' profile in the absence of brain tissue. These data indicate that apparent [3H]MDMA binding to rat brain homogenates results from artifactual of [3H]MDMA to glass fiber filter paper. In addition, uptake of [3H]MDMA into rat brain synaptosomes could not be detected. We conclude the [3H]MDMA has limited usefulness in radioligand binding studies.

Intracerebroventricular (i.c.v.) administration of 2 micrograms neurotensin, a brain and gastro-intestinal peptide which elicits various behavioral responses, diminishes grooming but stimulates paper shredding behavior of rats evoked by water immersion. Neither naloxone (2 micrograms i.c.v.) nor haloperidol (2 micrograms i.c.v.) affect grooming and paper shredding behavior as observed following water immersion of rats.

Psychopharmacology has had some bad publicity lately. Frankly, there have been some major problems along the way in developing new effective drugs for psychiatric disorders. After a prolonged period of high investments but low success rates, big pharmaceutical companies seem to retract their activities in the psychopharmacology field. Yet, the burden of mental disorders is likely to keep on growing in the next decades. In this position paper, we focus on drug development for depression and anxiety disorders, to narrow the scope of the assay. We describe the current situation of the psychopharmacology field, and analyse some of the methods and paradigms that have brought us here, but which should perhaps change to bring us even further. In addition, some of the factors contributing to the current stagnation in psychopharmacology are discussed. Finally, we suggest a number of changes that could lead to a more rational strategy for central nervous system drug development and which may circumvent some of the pitfalls leading to "me too" approaches. Central to the suggested changes, is the notion that mental disorders do not lead to several symptoms, but a network of causally related symptoms convolutes into a mental disorder. We call upon academia to put these changes in the early phases of drug development into effect.

3H-Tryptophan was administered intravenously to conscious mice by injection or constant rate infusion. Endogenous tryptophan and 5-hydroxytryptamine levels were not significantly altered by this treatment. 3H-5-HT formed in vivo from the labelled precursor was identified by paper chromatography. Following a pulse-injection of 3H-tryptophan the level of 3H-5-HT in brain rapidly increased reaching a peak within 30 min. Pretreatment of the animals with the tryptophan hydroxylase inhibitor, p-chlorophenylalanine or reserpine, markedly reduced the accumulation of 3H-5-HT. Following the initial peak, the content of 3H-5-HT declined over several hours at a rate that seemed to be exponential between 30 and 180 min after precursor administration with a half-life of about 60 min. Treatment with p-chloro-phenylalanine 60 min after precursor administration did not accelerate the rate of disappearance of 3H-5-HT indicating that the decline of 3H-5-HT content is predominantly determined by turnover of the amine. The procedures were used to study the effect of LSD-25 on mouse brain serotonin metabolism. Following LSD-25 treatment the rates of accumulation and disappearance of 3H-5-HT after 3H-tryptophan administration were markedly reduced. The contents of labelled tryptophan and endogenous tryptophan and 5-HT levels were not altered by drug treatment. The results indicate that LSD-25 reduces both synthesis and turnover of 5-HT in brain. The LSD-25 analogue BOL 148 showed no effect on brain 5-HT metabolism. Possible mechanisms of action of LSD-25 are discussed.

The separation of metabolites from the urine of rats given 14C-neostigmine is described, using ion exchange chromatography and paper chromatography. 3-Hydroxyphenyltrimethyl ammonium (3-OH PTMA) was isolated and its identity confirmed by UV spectroscopy. The glucuronide of 3-OH PTMA was also isolated and after hydrolysis with β-glucuronidase it was found to be the monoglucuronide conjugate. Small amounts of 3-hydroxyphenyl-dimethyl amine (3-OH PDMA) and two unidentified metabolites were detected by paper chromatography of urine from rats given 14C-neostigmine daily for seven days. It is suggested that 3-OH PDMA also forms a glucuronide.

Spironolactone increased the total excretion of radioactivity in female rats given specific labelled 3 H-digoxin. This increase was due to enhanced fecal excretion while urinary elimination of radioactivity and blood tritium levels were reduced. The ratio of total excreted digoxin to its metabolites which was measured by paper and thin-layer chromatography was changed from 28%: 72% under control conditions to 2% : 98% during spironolactone treatment. This increased excretion of metabolites mainly concerned the aqueous soluble compounds, the digoxigenin monodigitoxoside and the digoxigenin. The excretion of the genin was enhanced in urine only. After metabolism of 3 H-digoxin could still be observed 25 days after discontinuation of treatment with spironolactone. It is concluded that in rats spironolactone increased the metabolism of digoxin by induction of hepatic microsomal enzyme activity.

The rate and pattern of neostigmine metabolism in different tissues of rat were studied after acute and chronic subcutaneous administration of the 14 C-labelled drug. Radioactivity in plasma, liver, kidney and muscle was determined and the analysis of different metabolites and neostigmine was carried out by paper chromatography. The t 1 2 of parent drug and its metabolites is on the average 10 min in plasma, 33 min in liver, and 1.5 hr in muscle. Neostigmine is metabolised in the liver at a rate of 2.24 × 10 −2 μ mol/min/g (wet weight) and 3-hydroxyphenyltri-methylammonium (3-HPTMA) is metabolized at a rate of 2.89 × 10 −2 μ mol/min/g. Metabolic degradation of neostigmine proceeds in muscle at a rate of 2.1 × 10 −2 μ mol/g. During chronic administration, the concentration of neostigmine and its metabolites rose in liver between day one to eight from 0.63 to 5.89 μmolg of tissue and in muscle from 0.085 to 0.39 μmol/g of tissue. Liver contained the highest concentration of glucuronide of 3-HPTMA (G-3-HPTMA) followed by neostigmine and 3-HPTMA. G-3-HPTMA concentration was 0.321 μmol on day 1 and increased to 2.89 μmol/g liver on day 8. The neostigmine concentration increased from 0.14 to 1.62 μmol/g of liver during the same period. Similar increases in the concentration of neostigmine and its metabolites were also obseved in muscle under the same conditions. 3-Hydroxyphenyldimethyl amine (3-HPDMA) and an unknown metabolite also consistently increased in liver and muscle.

Tyrosine- 14 C was administered to conscious mice by i.v. injection or constant rate i.v. infusion. The time courses for accumulation and disappearance of tyrosine- 14 C, dopamine- 14 C and noradrenaline- 14 C in brain were determined. Significant amounts of adrenaline- 14 C were not formed from the labelled precursor as shown by paper chromatography. Following labelling of the catecholamine stores in brain by i.v. injection of tyrosine- 14 C the decline of 14 C-catecholamine levels yielded linear semilog plots between 2 and 7 hr after precursor administration. The slope of the curves for 14 C-catecholamine disappearance was not altered on treatment with the tyrosine hydroxylase inhibitor α-methyl-tyrosine. When tyrosine- 14 C was administered by constant rate i.v. infusion the contents in brain of labelled dopamine and noradrenaline increased with time demonstrating that the rate of synthesis of labelled amines exceeded the rates of catabolism and release. The procedures were used to study the effects of promethazine, levomepromazine, chlorpromazine, perphenazine and chlorprothixene. The neuroleptic phenothiazine analogues, but not the non-neuroleptic promethazine, accelerated the disappearance rates of both dopamine- 14 C and noradrenaline- 14 C. The clinically, most potent neuroleptic seemed to accelerate dopamine- 14 C disappearance somewhat more than noradrenaline- 14 C disappearance. During infusion of tyrosine- 14 C all neuroleptics accelerated the accumulation of dopamine- 14 C more than that of noradrenaline- 14 C. It is suggested that neuroleptic phenothiazine analogues accelerate turnover of both dopamine and noradrenaline. Neuroleptic properties seemed to be best correlated to an increased synthesis and turnover of dopamine. Sedative properties might be better correlated to an increased synthesis and turnover of noradrenaline.

F.W.KOSS and W.LAMPRECHT, Experimental investigations in choleresis. European J. Pharmacol. 4 (1968) 215–223. Biochemical, pharmacokinetical, and pharmacological data are presented concerning substances known to influence bile flow in the rat. 1) All substances investigated in the rat are excreted in the bile, however, the excretion rates show large deviations and the final quantity excreted into the bile differs markedly. 2) All substances investigated are metabolized in the liver to compounds more polar than the original drugs. 3) Quantitatively all substances show identical choleretic effects, if related to the metabolites excreted in the bile and if compared on a molar basis. In the rat 1 μmole of the compounds excreted in the bile gives rise to about 20 mg bile.

The metabolism and biliary excretion of trimethyl-14C(3-hydroxyphenyl)ammonium iodide (14C-trimophonium iodide) was studied in the rat. After i.v. injection, approximately 3% of the dose was recovered from bile within 4 hr. 80–90% of the radioactivity in bile was excreted as 14C-trimophonium glucuronide; a further 10–20% was eliminated as 3-dimethylaminophenyl glucuronide. Indirect and circumstantial evidence suggests that these two glucuronide conjugates may be formed at different sites in the liver cell. Only minor amounts of unchanged 14C-trimophonium were detected in bile.

Apomorphine undergoes O-methylation in rat liver. Apocodeine, the methylated product, can be identified by paper chromatography. The catechol-O-methyltransferase inhibitors, pyrogallol and 3,4-dimethoxy-5-hydroxy-benzoic acid prolong apomorphine-induced stereotyped behaviour (ASB). This suggest that O-methylation is an important route in the biotransformation of apomorphine in vivo. Acetoaminophen also prolongs ASB; this may be related to competition for the enzymes catalyzing the glucuronidation of apomorphine.

The base composition and quantitative alterations in purine and pyrimidine of ribonucleic (RNA) and deoxyribonucleic acid (DNA) have been studied in the glandular (pyloric) and membranous (rumenal parts of the rat stomach after prolonged atropine treatment. Prolonged atropine treatment produced alterations in both composition and total quantities of purine and pyrimidine bases of RNA in the membranous and glandular parts of the rat stomach, while the purine and pyrimidine bases of DNA were altered only quantitatively. Alterations in base composition and quantities of purine and pyrimidine bases of RNA were only reversible in the membranous part of the stomach in 10 days after cessation of treatment.

The anesthetic action of progesterone was stronger in female rats than in male rats. The formation of hydroxylated metabolites from progesterone was greater with liver microsomes from male rats, whereas formation of Δ4-reduced metabolites from progesterone was greater with liver microsomes from female rats. On the other hand, in mice there was no sex difference in the anesthetic action and in vitro metabolism of progesterone. The levels of radioactive polar metabolites in the brain, serum, liver and kidney were higher in male rats injected with tritiated progesterone, whereas the levels of radioactive non-polar metabolites in these tissues were higher in female rats. These results suggest that the stronger anesthetic action of progesterone in female rats is associated with higher tissue levels of progesterone and Δ4-reduced metabolites, possessing the anesthetic action.

The incorporation of triethylcholine (TEC) into synaptosomal and synaptic vesicle fractions prepared from guinea pig cerebral cortices was investigated. TEC was tritium labelled by a catalytic exchange process and purified by thin layer chromatography. 3H-TEC was incorporated into isolated synaptosomal fractions in both tris medium and a complete medium containing an external energy source. In this medium about 50% of the 3H-TEC incorporated was taken up into a chloroform-soluble fraction; almost no uptake into chloroform was demonstrated in the complete medium. After incubation of 3H-TEC with isolated synaptosomal fractions the 3H-TEC was shown to be localized in the subsynaptosomal synaptic vesicle fraction. The uptake process for 3H-TEC is inhibited by high concentrations of hemicholinium and choline. The temperature and time studies suggest that in synaptosomes an uptake process for TEC exists similar to that which has been observed for choline.